| Message ID | d93962cdc5a32fe99e6e5a25172920d28583aa6a.1542219596.git-series.plaes@plaes.org (mailing list archive) |
|---|---|
| State | Changes Requested |
| Delegated to: | Kalle Valo |
| Headers | show |
| Series | wireless: Use common cordic algorithm for b43 driver | expand |
On Wed, 14 Nov 2018 20:27:52 +0200 Priit Laes <plaes@plaes.org> wrote: > Kernel library has a common cordic algorithm which is identical > to internally implementatd one, so use it and drop the duplicate > implementation. In v2 of the series it has been said that: Arend van Spriel <arend.vanspriel@broadcom.com> wrote: > I recall doing a comparison between the algorithms and thought I put > that in the original commit message. However, it is not there. It is not > exactly the same as in b43 so there are difference for certain angles, > most results are the same however. This implementation is slightly more > accurate on the full scale. That's not my definition of "identical". Please do not apply this patch without doing a thorough regression test on actual b43 LP hardware.
On Wed, Nov 14, 2018 at 07:46:28PM +0100, Michael Büsch wrote: > On Wed, 14 Nov 2018 20:27:52 +0200 > Priit Laes <plaes@plaes.org> wrote: > > > Kernel library has a common cordic algorithm which is identical > > to internally implementatd one, so use it and drop the duplicate > > implementation. > > > In v2 of the series it has been said that: > > Arend van Spriel <arend.vanspriel@broadcom.com> wrote: > > I recall doing a comparison between the algorithms and thought I put > > that in the original commit message. However, it is not there. It is not > > exactly the same as in b43 so there are difference for certain angles, > > most results are the same however. This implementation is slightly more > > accurate on the full scale. > > > That's not my definition of "identical". > > Please do not apply this patch without doing a thorough regression test > on actual b43 LP hardware. Indeed, there's a big discrepancy in the results of both algorithms. Here's the test script: https://gist.github.com/plaes/284993a4fc65e0926d0628a11f0cf874 So at current state, this is self-NAK from me too and this patch should be dropped. > > -- > Michael
Priit Laes <plaes@plaes.org> writes: > On Wed, Nov 14, 2018 at 07:46:28PM +0100, Michael Büsch wrote: >> On Wed, 14 Nov 2018 20:27:52 +0200 >> Priit Laes <plaes@plaes.org> wrote: >> >> > Kernel library has a common cordic algorithm which is identical >> > to internally implementatd one, so use it and drop the duplicate >> > implementation. >> >> >> In v2 of the series it has been said that: >> >> Arend van Spriel <arend.vanspriel@broadcom.com> wrote: >> > I recall doing a comparison between the algorithms and thought I put >> > that in the original commit message. However, it is not there. It is not >> > exactly the same as in b43 so there are difference for certain angles, >> > most results are the same however. This implementation is slightly more >> > accurate on the full scale. >> >> >> That's not my definition of "identical". >> >> Please do not apply this patch without doing a thorough regression test >> on actual b43 LP hardware. > > Indeed, there's a big discrepancy in the results of both algorithms. > > Here's the test script: > https://gist.github.com/plaes/284993a4fc65e0926d0628a11f0cf874 > > So at current state, this is self-NAK from me too and this patch should > be dropped. Ok, I'll drop patch 3 but keep patches 1-2 still in review. Thanks for verifying this! But of course it would be better if somebody could test this properly on a real device. When that happens, please resubmit patch 3.
On 11/14/18 12:27 PM, Priit Laes wrote: > Kernel library has a common cordic algorithm which is identical > to internally implementatd one, so use it and drop the duplicate > implementation. > > Signed-off-by: Priit Laes <plaes@plaes.org> > --- > drivers/net/wireless/broadcom/b43/Kconfig | 1 +- > drivers/net/wireless/broadcom/b43/phy_common.c | 47 +------------------- > drivers/net/wireless/broadcom/b43/phy_common.h | 9 +---- > drivers/net/wireless/broadcom/b43/phy_lp.c | 13 ++--- > drivers/net/wireless/broadcom/b43/phy_n.c | 13 ++--- > 5 files changed, 15 insertions(+), 68 deletions(-) > > diff --git a/drivers/net/wireless/broadcom/b43/Kconfig b/drivers/net/wireless/broadcom/b43/Kconfig > index fba8560..3e41457 100644 > --- a/drivers/net/wireless/broadcom/b43/Kconfig > +++ b/drivers/net/wireless/broadcom/b43/Kconfig > @@ -4,6 +4,7 @@ config B43 > select BCMA if B43_BCMA > select SSB if B43_SSB > select FW_LOADER > + select CORDIC > ---help--- > b43 is a driver for the Broadcom 43xx series wireless devices. > > diff --git a/drivers/net/wireless/broadcom/b43/phy_common.c b/drivers/net/wireless/broadcom/b43/phy_common.c > index 85f2ca9..98c4fa5 100644 > --- a/drivers/net/wireless/broadcom/b43/phy_common.c > +++ b/drivers/net/wireless/broadcom/b43/phy_common.c > @@ -604,50 +604,3 @@ void b43_phy_force_clock(struct b43_wldev *dev, bool force) > #endif > } > } > - > -/* http://bcm-v4.sipsolutions.net/802.11/PHY/Cordic */ > -struct b43_c32 b43_cordic(int theta) > -{ > - static const u32 arctg[] = { > - 2949120, 1740967, 919879, 466945, 234379, 117304, > - 58666, 29335, 14668, 7334, 3667, 1833, > - 917, 458, 229, 115, 57, 29, > - }; > - u8 i; > - s32 tmp; > - s8 signx = 1; > - u32 angle = 0; > - struct b43_c32 ret = { .i = 39797, .q = 0, }; > - > - while (theta > (180 << 16)) > - theta -= (360 << 16); > - while (theta < -(180 << 16)) > - theta += (360 << 16); > - > - if (theta > (90 << 16)) { > - theta -= (180 << 16); > - signx = -1; > - } else if (theta < -(90 << 16)) { > - theta += (180 << 16); > - signx = -1; > - } > - > - for (i = 0; i <= 17; i++) { > - if (theta > angle) { > - tmp = ret.i - (ret.q >> i); > - ret.q += ret.i >> i; > - ret.i = tmp; > - angle += arctg[i]; > - } else { > - tmp = ret.i + (ret.q >> i); > - ret.q -= ret.i >> i; > - ret.i = tmp; > - angle -= arctg[i]; > - } > - } > - > - ret.i *= signx; > - ret.q *= signx; > - > - return ret; > -} > diff --git a/drivers/net/wireless/broadcom/b43/phy_common.h b/drivers/net/wireless/broadcom/b43/phy_common.h > index 57a1ad8..4213cac 100644 > --- a/drivers/net/wireless/broadcom/b43/phy_common.h > +++ b/drivers/net/wireless/broadcom/b43/phy_common.h > @@ -7,13 +7,6 @@ > > struct b43_wldev; > > -/* Complex number using 2 32-bit signed integers */ > -struct b43_c32 { s32 i, q; }; > - > -#define CORDIC_CONVERT(value) (((value) >= 0) ? \ > - ((((value) >> 15) + 1) >> 1) : \ > - -((((-(value)) >> 15) + 1) >> 1)) > - > /* PHY register routing bits */ > #define B43_PHYROUTE 0x0C00 /* PHY register routing bits mask */ > #define B43_PHYROUTE_BASE 0x0000 /* Base registers */ > @@ -450,6 +443,4 @@ bool b43_is_40mhz(struct b43_wldev *dev); > > void b43_phy_force_clock(struct b43_wldev *dev, bool force); > > -struct b43_c32 b43_cordic(int theta); > - > #endif /* LINUX_B43_PHY_COMMON_H_ */ > diff --git a/drivers/net/wireless/broadcom/b43/phy_lp.c b/drivers/net/wireless/broadcom/b43/phy_lp.c > index 6922cbb..1718e3b 100644 > --- a/drivers/net/wireless/broadcom/b43/phy_lp.c > +++ b/drivers/net/wireless/broadcom/b43/phy_lp.c > @@ -23,6 +23,7 @@ > > */ > > +#include <linux/cordic.h> > #include <linux/slab.h> > > #include "b43.h" > @@ -1780,9 +1781,9 @@ static void lpphy_start_tx_tone(struct b43_wldev *dev, s32 freq, u16 max) > { > struct b43_phy_lp *lpphy = dev->phy.lp; > u16 buf[64]; > - int i, samples = 0, angle = 0; > + int i, samples = 0, theta = 0; > int rotation = (((36 * freq) / 20) << 16) / 100; > - struct b43_c32 sample; > + struct cordic_iq sample; > > lpphy->tx_tone_freq = freq; > > @@ -1798,10 +1799,10 @@ static void lpphy_start_tx_tone(struct b43_wldev *dev, s32 freq, u16 max) > } > > for (i = 0; i < samples; i++) { > - sample = b43_cordic(angle); > - angle += rotation; > - buf[i] = CORDIC_CONVERT((sample.i * max) & 0xFF) << 8; > - buf[i] |= CORDIC_CONVERT((sample.q * max) & 0xFF); > + sample = cordic_calc_iq(theta); > + theta += rotation; > + buf[i] = CORDIC_FLOAT((sample.i * max) & 0xFF) << 8; > + buf[i] |= CORDIC_FLOAT((sample.q * max) & 0xFF); > } > > b43_lptab_write_bulk(dev, B43_LPTAB16(5, 0), samples, buf); > diff --git a/drivers/net/wireless/broadcom/b43/phy_n.c b/drivers/net/wireless/broadcom/b43/phy_n.c > index 44ab080..1f9378a 100644 > --- a/drivers/net/wireless/broadcom/b43/phy_n.c > +++ b/drivers/net/wireless/broadcom/b43/phy_n.c > @@ -23,6 +23,7 @@ > > */ > > +#include <linux/cordic.h> > #include <linux/delay.h> > #include <linux/slab.h> > #include <linux/types.h> > @@ -1513,7 +1514,7 @@ static void b43_radio_init2055(struct b43_wldev *dev) > > /* http://bcm-v4.sipsolutions.net/802.11/PHY/N/LoadSampleTable */ > static int b43_nphy_load_samples(struct b43_wldev *dev, > - struct b43_c32 *samples, u16 len) { > + struct cordic_iq *samples, u16 len) { > struct b43_phy_n *nphy = dev->phy.n; > u16 i; > u32 *data; > @@ -1544,7 +1545,7 @@ static u16 b43_nphy_gen_load_samples(struct b43_wldev *dev, u32 freq, u16 max, > { > int i; > u16 bw, len, rot, angle; > - struct b43_c32 *samples; > + struct cordic_iq *samples; > > bw = b43_is_40mhz(dev) ? 40 : 20; > len = bw << 3; > @@ -1561,7 +1562,7 @@ static u16 b43_nphy_gen_load_samples(struct b43_wldev *dev, u32 freq, u16 max, > len = bw << 1; > } > > - samples = kcalloc(len, sizeof(struct b43_c32), GFP_KERNEL); > + samples = kcalloc(len, sizeof(struct cordic_iq), GFP_KERNEL); > if (!samples) { > b43err(dev->wl, "allocation for samples generation failed\n"); > return 0; > @@ -1570,10 +1571,10 @@ static u16 b43_nphy_gen_load_samples(struct b43_wldev *dev, u32 freq, u16 max, > angle = 0; > > for (i = 0; i < len; i++) { > - samples[i] = b43_cordic(angle); > + samples[i] = cordic_calc_iq(angle); > angle += rot; > - samples[i].q = CORDIC_CONVERT(samples[i].q * max); > - samples[i].i = CORDIC_CONVERT(samples[i].i * max); > + samples[i].q = CORDIC_FLOAT(samples[i].q * max); > + samples[i].i = CORDIC_FLOAT(samples[i].i * max); > } > > i = b43_nphy_load_samples(dev, samples, len); There is a fundamental flaw in this patch. Routine b43_cordic() takes an angle in degrees scaled by 2^16, whereas cordic_calc_iq() takes an angle in degrees. For a given input, the two routines must get different answers. At a minimum, the calculation of rot would need to remove the left shift of 16. From what I see of the two algorithms, the method is identical once the differences in scaling are handled. Even so, applying this patch to b43 leads to a series of B43 error messages followed by a crash in kfree. Just to add to the level of rejection: NACK. Larry
On Sat, Nov 17, 2018 at 09:31:35PM -0600, Larry Finger wrote: > On 11/14/18 12:27 PM, Priit Laes wrote: > > Kernel library has a common cordic algorithm which is identical > > to internally implementatd one, so use it and drop the duplicate > > implementation. > > > > Signed-off-by: Priit Laes <plaes@plaes.org> > > --- > > drivers/net/wireless/broadcom/b43/Kconfig | 1 +- > > drivers/net/wireless/broadcom/b43/phy_common.c | 47 +------------------- > > drivers/net/wireless/broadcom/b43/phy_common.h | 9 +---- > > drivers/net/wireless/broadcom/b43/phy_lp.c | 13 ++--- > > drivers/net/wireless/broadcom/b43/phy_n.c | 13 ++--- > > 5 files changed, 15 insertions(+), 68 deletions(-) > > > > diff --git a/drivers/net/wireless/broadcom/b43/Kconfig b/drivers/net/wireless/broadcom/b43/Kconfig > > index fba8560..3e41457 100644 > > --- a/drivers/net/wireless/broadcom/b43/Kconfig > > +++ b/drivers/net/wireless/broadcom/b43/Kconfig > > @@ -4,6 +4,7 @@ config B43 > > select BCMA if B43_BCMA > > select SSB if B43_SSB > > select FW_LOADER > > + select CORDIC > > ---help--- > > b43 is a driver for the Broadcom 43xx series wireless devices. > > diff --git a/drivers/net/wireless/broadcom/b43/phy_common.c b/drivers/net/wireless/broadcom/b43/phy_common.c > > index 85f2ca9..98c4fa5 100644 > > --- a/drivers/net/wireless/broadcom/b43/phy_common.c > > +++ b/drivers/net/wireless/broadcom/b43/phy_common.c > > @@ -604,50 +604,3 @@ void b43_phy_force_clock(struct b43_wldev *dev, bool force) > > #endif > > } > > } > > - > > -/* http://bcm-v4.sipsolutions.net/802.11/PHY/Cordic */ > > -struct b43_c32 b43_cordic(int theta) > > -{ > > - static const u32 arctg[] = { > > - 2949120, 1740967, 919879, 466945, 234379, 117304, > > - 58666, 29335, 14668, 7334, 3667, 1833, > > - 917, 458, 229, 115, 57, 29, > > - }; > > - u8 i; > > - s32 tmp; > > - s8 signx = 1; > > - u32 angle = 0; > > - struct b43_c32 ret = { .i = 39797, .q = 0, }; > > - > > - while (theta > (180 << 16)) > > - theta -= (360 << 16); > > - while (theta < -(180 << 16)) > > - theta += (360 << 16); > > - > > - if (theta > (90 << 16)) { > > - theta -= (180 << 16); > > - signx = -1; > > - } else if (theta < -(90 << 16)) { > > - theta += (180 << 16); > > - signx = -1; > > - } > > - > > - for (i = 0; i <= 17; i++) { > > - if (theta > angle) { > > - tmp = ret.i - (ret.q >> i); > > - ret.q += ret.i >> i; > > - ret.i = tmp; > > - angle += arctg[i]; > > - } else { > > - tmp = ret.i + (ret.q >> i); > > - ret.q -= ret.i >> i; > > - ret.i = tmp; > > - angle -= arctg[i]; > > - } > > - } > > - > > - ret.i *= signx; > > - ret.q *= signx; > > - > > - return ret; > > -} > > diff --git a/drivers/net/wireless/broadcom/b43/phy_common.h b/drivers/net/wireless/broadcom/b43/phy_common.h > > index 57a1ad8..4213cac 100644 > > --- a/drivers/net/wireless/broadcom/b43/phy_common.h > > +++ b/drivers/net/wireless/broadcom/b43/phy_common.h > > @@ -7,13 +7,6 @@ > > struct b43_wldev; > > -/* Complex number using 2 32-bit signed integers */ > > -struct b43_c32 { s32 i, q; }; > > - > > -#define CORDIC_CONVERT(value) (((value) >= 0) ? \ > > - ((((value) >> 15) + 1) >> 1) : \ > > - -((((-(value)) >> 15) + 1) >> 1)) > > - > > /* PHY register routing bits */ > > #define B43_PHYROUTE 0x0C00 /* PHY register routing bits mask */ > > #define B43_PHYROUTE_BASE 0x0000 /* Base registers */ > > @@ -450,6 +443,4 @@ bool b43_is_40mhz(struct b43_wldev *dev); > > void b43_phy_force_clock(struct b43_wldev *dev, bool force); > > -struct b43_c32 b43_cordic(int theta); > > - > > #endif /* LINUX_B43_PHY_COMMON_H_ */ > > diff --git a/drivers/net/wireless/broadcom/b43/phy_lp.c b/drivers/net/wireless/broadcom/b43/phy_lp.c > > index 6922cbb..1718e3b 100644 > > --- a/drivers/net/wireless/broadcom/b43/phy_lp.c > > +++ b/drivers/net/wireless/broadcom/b43/phy_lp.c > > @@ -23,6 +23,7 @@ > > */ > > +#include <linux/cordic.h> > > #include <linux/slab.h> > > #include "b43.h" > > @@ -1780,9 +1781,9 @@ static void lpphy_start_tx_tone(struct b43_wldev *dev, s32 freq, u16 max) > > { > > struct b43_phy_lp *lpphy = dev->phy.lp; > > u16 buf[64]; > > - int i, samples = 0, angle = 0; > > + int i, samples = 0, theta = 0; > > int rotation = (((36 * freq) / 20) << 16) / 100; > > - struct b43_c32 sample; > > + struct cordic_iq sample; > > lpphy->tx_tone_freq = freq; > > @@ -1798,10 +1799,10 @@ static void lpphy_start_tx_tone(struct b43_wldev *dev, s32 freq, u16 max) > > } > > for (i = 0; i < samples; i++) { > > - sample = b43_cordic(angle); > > - angle += rotation; > > - buf[i] = CORDIC_CONVERT((sample.i * max) & 0xFF) << 8; > > - buf[i] |= CORDIC_CONVERT((sample.q * max) & 0xFF); > > + sample = cordic_calc_iq(theta); > > + theta += rotation; > > + buf[i] = CORDIC_FLOAT((sample.i * max) & 0xFF) << 8; > > + buf[i] |= CORDIC_FLOAT((sample.q * max) & 0xFF); > > } > > b43_lptab_write_bulk(dev, B43_LPTAB16(5, 0), samples, buf); > > diff --git a/drivers/net/wireless/broadcom/b43/phy_n.c b/drivers/net/wireless/broadcom/b43/phy_n.c > > index 44ab080..1f9378a 100644 > > --- a/drivers/net/wireless/broadcom/b43/phy_n.c > > +++ b/drivers/net/wireless/broadcom/b43/phy_n.c > > @@ -23,6 +23,7 @@ > > */ > > +#include <linux/cordic.h> > > #include <linux/delay.h> > > #include <linux/slab.h> > > #include <linux/types.h> > > @@ -1513,7 +1514,7 @@ static void b43_radio_init2055(struct b43_wldev *dev) > > /* http://bcm-v4.sipsolutions.net/802.11/PHY/N/LoadSampleTable */ > > static int b43_nphy_load_samples(struct b43_wldev *dev, > > - struct b43_c32 *samples, u16 len) { > > + struct cordic_iq *samples, u16 len) { > > struct b43_phy_n *nphy = dev->phy.n; > > u16 i; > > u32 *data; > > @@ -1544,7 +1545,7 @@ static u16 b43_nphy_gen_load_samples(struct b43_wldev *dev, u32 freq, u16 max, > > { > > int i; > > u16 bw, len, rot, angle; > > - struct b43_c32 *samples; > > + struct cordic_iq *samples; > > bw = b43_is_40mhz(dev) ? 40 : 20; > > len = bw << 3; > > @@ -1561,7 +1562,7 @@ static u16 b43_nphy_gen_load_samples(struct b43_wldev *dev, u32 freq, u16 max, > > len = bw << 1; > > } > > - samples = kcalloc(len, sizeof(struct b43_c32), GFP_KERNEL); > > + samples = kcalloc(len, sizeof(struct cordic_iq), GFP_KERNEL); > > if (!samples) { > > b43err(dev->wl, "allocation for samples generation failed\n"); > > return 0; > > @@ -1570,10 +1571,10 @@ static u16 b43_nphy_gen_load_samples(struct b43_wldev *dev, u32 freq, u16 max, > > angle = 0; > > for (i = 0; i < len; i++) { > > - samples[i] = b43_cordic(angle); > > + samples[i] = cordic_calc_iq(angle); > > angle += rot; > > - samples[i].q = CORDIC_CONVERT(samples[i].q * max); > > - samples[i].i = CORDIC_CONVERT(samples[i].i * max); > > + samples[i].q = CORDIC_FLOAT(samples[i].q * max); > > + samples[i].i = CORDIC_FLOAT(samples[i].i * max); > > } > > i = b43_nphy_load_samples(dev, samples, len); > > There is a fundamental flaw in this patch. Routine b43_cordic() takes an > angle in degrees scaled by 2^16, whereas cordic_calc_iq() takes an angle in > degrees. For a given input, the two routines must get different answers. At > a minimum, the calculation of rot would need to remove the left shift of 16. Thanks for the hint. I modified my "test harness" a bit to plot out values from -360 .. 360 and transformed the theta for b43_cordic argument using CORDIC_FIXED macro: b43_cordic(CORDIC_FIXED(theta)); cordic_calc_iq(theta); Then I plotted the results and well.. they are not that pretty. While the results give identical answers between certain ranges of degrees, the cordic algorithm for b43 seems to be broken for certain ranges: (-270..-180 ; -90 .. 0; 90.. 180 and 270..360). You can find my test harnesses here: https://gist.github.com/plaes/284993a4fc65e0926d0628a11f0cf874 > > From what I see of the two algorithms, the method is identical once the > differences in scaling are handled. Even so, applying this patch to b43 > leads to a series of B43 error messages followed by a crash in kfree. > > Just to add to the level of rejection: NACK. > > Larry
On 11/18/18 2:23 AM, Priit Laes wrote: > On Sat, Nov 17, 2018 at 09:31:35PM -0600, Larry Finger wrote: >> On 11/14/18 12:27 PM, Priit Laes wrote: >>> Kernel library has a common cordic algorithm which is identical >>> to internally implementatd one, so use it and drop the duplicate >>> implementation. >>> >>> Signed-off-by: Priit Laes <plaes@plaes.org> >>> --- >>> drivers/net/wireless/broadcom/b43/Kconfig | 1 +- >>> drivers/net/wireless/broadcom/b43/phy_common.c | 47 +------------------- >>> drivers/net/wireless/broadcom/b43/phy_common.h | 9 +---- >>> drivers/net/wireless/broadcom/b43/phy_lp.c | 13 ++--- >>> drivers/net/wireless/broadcom/b43/phy_n.c | 13 ++--- >>> 5 files changed, 15 insertions(+), 68 deletions(-) >>> >>> diff --git a/drivers/net/wireless/broadcom/b43/Kconfig b/drivers/net/wireless/broadcom/b43/Kconfig >>> index fba8560..3e41457 100644 >>> --- a/drivers/net/wireless/broadcom/b43/Kconfig >>> +++ b/drivers/net/wireless/broadcom/b43/Kconfig >>> @@ -4,6 +4,7 @@ config B43 >>> select BCMA if B43_BCMA >>> select SSB if B43_SSB >>> select FW_LOADER >>> + select CORDIC >>> ---help--- >>> b43 is a driver for the Broadcom 43xx series wireless devices. >>> diff --git a/drivers/net/wireless/broadcom/b43/phy_common.c b/drivers/net/wireless/broadcom/b43/phy_common.c >>> index 85f2ca9..98c4fa5 100644 >>> --- a/drivers/net/wireless/broadcom/b43/phy_common.c >>> +++ b/drivers/net/wireless/broadcom/b43/phy_common.c >>> @@ -604,50 +604,3 @@ void b43_phy_force_clock(struct b43_wldev *dev, bool force) >>> #endif >>> } >>> } >>> - >>> -/* http://bcm-v4.sipsolutions.net/802.11/PHY/Cordic */ >>> -struct b43_c32 b43_cordic(int theta) >>> -{ >>> - static const u32 arctg[] = { >>> - 2949120, 1740967, 919879, 466945, 234379, 117304, >>> - 58666, 29335, 14668, 7334, 3667, 1833, >>> - 917, 458, 229, 115, 57, 29, >>> - }; >>> - u8 i; >>> - s32 tmp; >>> - s8 signx = 1; >>> - u32 angle = 0; >>> - struct b43_c32 ret = { .i = 39797, .q = 0, }; >>> - >>> - while (theta > (180 << 16)) >>> - theta -= (360 << 16); >>> - while (theta < -(180 << 16)) >>> - theta += (360 << 16); >>> - >>> - if (theta > (90 << 16)) { >>> - theta -= (180 << 16); >>> - signx = -1; >>> - } else if (theta < -(90 << 16)) { >>> - theta += (180 << 16); >>> - signx = -1; >>> - } >>> - >>> - for (i = 0; i <= 17; i++) { >>> - if (theta > angle) { >>> - tmp = ret.i - (ret.q >> i); >>> - ret.q += ret.i >> i; >>> - ret.i = tmp; >>> - angle += arctg[i]; >>> - } else { >>> - tmp = ret.i + (ret.q >> i); >>> - ret.q -= ret.i >> i; >>> - ret.i = tmp; >>> - angle -= arctg[i]; >>> - } >>> - } >>> - >>> - ret.i *= signx; >>> - ret.q *= signx; >>> - >>> - return ret; >>> -} >>> diff --git a/drivers/net/wireless/broadcom/b43/phy_common.h b/drivers/net/wireless/broadcom/b43/phy_common.h >>> index 57a1ad8..4213cac 100644 >>> --- a/drivers/net/wireless/broadcom/b43/phy_common.h >>> +++ b/drivers/net/wireless/broadcom/b43/phy_common.h >>> @@ -7,13 +7,6 @@ >>> struct b43_wldev; >>> -/* Complex number using 2 32-bit signed integers */ >>> -struct b43_c32 { s32 i, q; }; >>> - >>> -#define CORDIC_CONVERT(value) (((value) >= 0) ? \ >>> - ((((value) >> 15) + 1) >> 1) : \ >>> - -((((-(value)) >> 15) + 1) >> 1)) >>> - >>> /* PHY register routing bits */ >>> #define B43_PHYROUTE 0x0C00 /* PHY register routing bits mask */ >>> #define B43_PHYROUTE_BASE 0x0000 /* Base registers */ >>> @@ -450,6 +443,4 @@ bool b43_is_40mhz(struct b43_wldev *dev); >>> void b43_phy_force_clock(struct b43_wldev *dev, bool force); >>> -struct b43_c32 b43_cordic(int theta); >>> - >>> #endif /* LINUX_B43_PHY_COMMON_H_ */ >>> diff --git a/drivers/net/wireless/broadcom/b43/phy_lp.c b/drivers/net/wireless/broadcom/b43/phy_lp.c >>> index 6922cbb..1718e3b 100644 >>> --- a/drivers/net/wireless/broadcom/b43/phy_lp.c >>> +++ b/drivers/net/wireless/broadcom/b43/phy_lp.c >>> @@ -23,6 +23,7 @@ >>> */ >>> +#include <linux/cordic.h> >>> #include <linux/slab.h> >>> #include "b43.h" >>> @@ -1780,9 +1781,9 @@ static void lpphy_start_tx_tone(struct b43_wldev *dev, s32 freq, u16 max) >>> { >>> struct b43_phy_lp *lpphy = dev->phy.lp; >>> u16 buf[64]; >>> - int i, samples = 0, angle = 0; >>> + int i, samples = 0, theta = 0; >>> int rotation = (((36 * freq) / 20) << 16) / 100; >>> - struct b43_c32 sample; >>> + struct cordic_iq sample; >>> lpphy->tx_tone_freq = freq; >>> @@ -1798,10 +1799,10 @@ static void lpphy_start_tx_tone(struct b43_wldev *dev, s32 freq, u16 max) >>> } >>> for (i = 0; i < samples; i++) { >>> - sample = b43_cordic(angle); >>> - angle += rotation; >>> - buf[i] = CORDIC_CONVERT((sample.i * max) & 0xFF) << 8; >>> - buf[i] |= CORDIC_CONVERT((sample.q * max) & 0xFF); >>> + sample = cordic_calc_iq(theta); >>> + theta += rotation; >>> + buf[i] = CORDIC_FLOAT((sample.i * max) & 0xFF) << 8; >>> + buf[i] |= CORDIC_FLOAT((sample.q * max) & 0xFF); >>> } >>> b43_lptab_write_bulk(dev, B43_LPTAB16(5, 0), samples, buf); >>> diff --git a/drivers/net/wireless/broadcom/b43/phy_n.c b/drivers/net/wireless/broadcom/b43/phy_n.c >>> index 44ab080..1f9378a 100644 >>> --- a/drivers/net/wireless/broadcom/b43/phy_n.c >>> +++ b/drivers/net/wireless/broadcom/b43/phy_n.c >>> @@ -23,6 +23,7 @@ >>> */ >>> +#include <linux/cordic.h> >>> #include <linux/delay.h> >>> #include <linux/slab.h> >>> #include <linux/types.h> >>> @@ -1513,7 +1514,7 @@ static void b43_radio_init2055(struct b43_wldev *dev) >>> /* http://bcm-v4.sipsolutions.net/802.11/PHY/N/LoadSampleTable */ >>> static int b43_nphy_load_samples(struct b43_wldev *dev, >>> - struct b43_c32 *samples, u16 len) { >>> + struct cordic_iq *samples, u16 len) { >>> struct b43_phy_n *nphy = dev->phy.n; >>> u16 i; >>> u32 *data; >>> @@ -1544,7 +1545,7 @@ static u16 b43_nphy_gen_load_samples(struct b43_wldev *dev, u32 freq, u16 max, >>> { >>> int i; >>> u16 bw, len, rot, angle; >>> - struct b43_c32 *samples; >>> + struct cordic_iq *samples; >>> bw = b43_is_40mhz(dev) ? 40 : 20; >>> len = bw << 3; >>> @@ -1561,7 +1562,7 @@ static u16 b43_nphy_gen_load_samples(struct b43_wldev *dev, u32 freq, u16 max, >>> len = bw << 1; >>> } >>> - samples = kcalloc(len, sizeof(struct b43_c32), GFP_KERNEL); >>> + samples = kcalloc(len, sizeof(struct cordic_iq), GFP_KERNEL); >>> if (!samples) { >>> b43err(dev->wl, "allocation for samples generation failed\n"); >>> return 0; >>> @@ -1570,10 +1571,10 @@ static u16 b43_nphy_gen_load_samples(struct b43_wldev *dev, u32 freq, u16 max, >>> angle = 0; >>> for (i = 0; i < len; i++) { >>> - samples[i] = b43_cordic(angle); >>> + samples[i] = cordic_calc_iq(angle); >>> angle += rot; >>> - samples[i].q = CORDIC_CONVERT(samples[i].q * max); >>> - samples[i].i = CORDIC_CONVERT(samples[i].i * max); >>> + samples[i].q = CORDIC_FLOAT(samples[i].q * max); >>> + samples[i].i = CORDIC_FLOAT(samples[i].i * max); >>> } >>> i = b43_nphy_load_samples(dev, samples, len); >> >> There is a fundamental flaw in this patch. Routine b43_cordic() takes an >> angle in degrees scaled by 2^16, whereas cordic_calc_iq() takes an angle in >> degrees. For a given input, the two routines must get different answers. At >> a minimum, the calculation of rot would need to remove the left shift of 16. > > Thanks for the hint. I modified my "test harness" a bit to plot out values > from -360 .. 360 and transformed the theta for b43_cordic argument using CORDIC_FIXED macro: > > b43_cordic(CORDIC_FIXED(theta)); > cordic_calc_iq(theta); > > Then I plotted the results and well.. they are not that pretty. While the results give > identical answers between certain ranges of degrees, the cordic algorithm for b43 seems > to be broken for certain ranges: (-270..-180 ; -90 .. 0; 90.. 180 and 270..360). > > You can find my test harnesses here: > > https://gist.github.com/plaes/284993a4fc65e0926d0628a11f0cf874 I found a problem with the b43 implementation. The local variables for that routine includes u32 angle = 0; If one looks further down in the algorithm, if the reduced value of "theta" is less than 0, then "angle" should be negative. That causes the calculation to blow up. This explains why some ranges of angles got the same result for both routines. When that declaration is changed to "int angle = 0", the two routines give the same answer for all inputs. My test setup has a hardware failure, thus I cannot test your patch, but I now believe it to be correct. Thus your first and third patches may be annotated with ACKed-by: Larry Finger <Larry.Finger@lwfinger.net> One thing that should be done is to fix the error in the b43 code for stable as it was introduced in 2.6.34. I propose adding the attached patched to your series placed between your current 2nd and 3rd patches so that the old kernels get fixed. Of course, your 3rd patch will need to be revised. If all 4 of the patches get submitted together there will be no problems with the timing. My change will exist for seconds in the mainline kernel, but it will get propagated back through stable. Thanks, Larry From b42ae73ef7505de93e4c66fb9f66930e3f3d969a Mon Sep 17 00:00:00 2001 From: Larry Finger <Larry.Finger@lwfinger.net> Date: Sun, 18 Nov 2018 13:15:07 -0600 Subject: [PATCH] b43: Fix error in cordic routine MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit To: kvalo@codeaurora.org Cc: linux-wireless@vger.kernel.org The cordic routine for calculating sines and cosines that was added in commit 986504540306 ("b43: make cordic common (LP-PHY and N-PHY need it)") contains an error whereby a quantity declared u32 can in fact go negative. This problem was detected by Priit Laes who is switching b43 to use the routine in the library functions of the kernel. Fixes: 986504540306 ("b43: make cordic common (LP-PHY and N-PHY need it)") Reported-by: Priit Laes <plaes@plaes.org> Cc: Rafał Miłecki <zajec5@gmail.com> Cc: Stable <stable@vger.kernel.org> # 2.6.34 Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net> --- drivers/net/wireless/broadcom/b43/phy_common.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/net/wireless/broadcom/b43/phy_common.c b/drivers/net/wireless/broadcom/b43/phy_common.c index 85f2ca989565..ef3ffa5ad466 100644 --- a/drivers/net/wireless/broadcom/b43/phy_common.c +++ b/drivers/net/wireless/broadcom/b43/phy_common.c @@ -616,7 +616,7 @@ struct b43_c32 b43_cordic(int theta) u8 i; s32 tmp; s8 signx = 1; - u32 angle = 0; + s32 angle = 0; struct b43_c32 ret = { .i = 39797, .q = 0, }; while (theta > (180 << 16))
Larry Finger <Larry.Finger@lwfinger.net> writes: >>>> @@ -1570,10 +1571,10 @@ static u16 b43_nphy_gen_load_samples(struct b43_wldev *dev, u32 freq, u16 max, >>>> angle = 0; >>>> for (i = 0; i < len; i++) { >>>> - samples[i] = b43_cordic(angle); >>>> + samples[i] = cordic_calc_iq(angle); >>>> angle += rot; >>>> - samples[i].q = CORDIC_CONVERT(samples[i].q * max); >>>> - samples[i].i = CORDIC_CONVERT(samples[i].i * max); >>>> + samples[i].q = CORDIC_FLOAT(samples[i].q * max); >>>> + samples[i].i = CORDIC_FLOAT(samples[i].i * max); >>>> } >>>> i = b43_nphy_load_samples(dev, samples, len); >>> >>> There is a fundamental flaw in this patch. Routine b43_cordic() takes an >>> angle in degrees scaled by 2^16, whereas cordic_calc_iq() takes an angle in >>> degrees. For a given input, the two routines must get different answers. At >>> a minimum, the calculation of rot would need to remove the left shift of 16. >> >> Thanks for the hint. I modified my "test harness" a bit to plot out values >> from -360 .. 360 and transformed the theta for b43_cordic argument >> using CORDIC_FIXED macro: >> >> b43_cordic(CORDIC_FIXED(theta)); >> cordic_calc_iq(theta); >> >> Then I plotted the results and well.. they are not that pretty. >> While the results give >> identical answers between certain ranges of degrees, the cordic >> algorithm for b43 seems >> to be broken for certain ranges: (-270..-180 ; -90 .. 0; 90.. 180 and 270..360). >> >> You can find my test harnesses here: >> >> https://gist.github.com/plaes/284993a4fc65e0926d0628a11f0cf874 > > I found a problem with the b43 implementation. The local variables for > that routine includes > > u32 angle = 0; > > If one looks further down in the algorithm, if the reduced value of > "theta" is less than 0, then "angle" should be negative. That causes > the calculation to blow up. This explains why some ranges of angles > got the same result for both routines. When that declaration is > changed to "int angle = 0", the two routines give the same answer for > all inputs. > > My test setup has a hardware failure, thus I cannot test your patch, > but I now believe it to be correct. Thus your first and third patches > may be annotated with > ACKed-by: Larry Finger <Larry.Finger@lwfinger.net> > > One thing that should be done is to fix the error in the b43 code for > stable as it was introduced in 2.6.34. I propose adding the attached > patched to your series placed between your current 2nd and 3rd patches > so that the old kernels get fixed. Of course, your 3rd patch will need > to be revised. If all 4 of the patches get submitted together there > will be no problems with the timing. My change will exist for seconds > in the mainline kernel, but it will get propagated back through > stable. Sorry Larry, I'm not fully understanding what you mean here. So I'm going to just drop the whole series and assume that Priit will submit a new version. Please let me know if I should do something else.
On Mon, Nov 19, 2018 at 12:43:32PM +0200, Kalle Valo wrote: > Larry Finger <Larry.Finger@lwfinger.net> writes: > > >>>> @@ -1570,10 +1571,10 @@ static u16 b43_nphy_gen_load_samples(struct b43_wldev *dev, u32 freq, u16 max, > >>>> angle = 0; > >>>> for (i = 0; i < len; i++) { > >>>> - samples[i] = b43_cordic(angle); > >>>> + samples[i] = cordic_calc_iq(angle); > >>>> angle += rot; > >>>> - samples[i].q = CORDIC_CONVERT(samples[i].q * max); > >>>> - samples[i].i = CORDIC_CONVERT(samples[i].i * max); > >>>> + samples[i].q = CORDIC_FLOAT(samples[i].q * max); > >>>> + samples[i].i = CORDIC_FLOAT(samples[i].i * max); > >>>> } > >>>> i = b43_nphy_load_samples(dev, samples, len); > >>> > >>> There is a fundamental flaw in this patch. Routine b43_cordic() takes an > >>> angle in degrees scaled by 2^16, whereas cordic_calc_iq() takes an angle in > >>> degrees. For a given input, the two routines must get different answers. At > >>> a minimum, the calculation of rot would need to remove the left shift of 16. > >> > >> Thanks for the hint. I modified my "test harness" a bit to plot out values > >> from -360 .. 360 and transformed the theta for b43_cordic argument > >> using CORDIC_FIXED macro: > >> > >> b43_cordic(CORDIC_FIXED(theta)); > >> cordic_calc_iq(theta); > >> > >> Then I plotted the results and well.. they are not that pretty. > >> While the results give > >> identical answers between certain ranges of degrees, the cordic > >> algorithm for b43 seems > >> to be broken for certain ranges: (-270..-180 ; -90 .. 0; 90.. 180 and 270..360). > >> > >> You can find my test harnesses here: > >> > >> https://gist.github.com/plaes/284993a4fc65e0926d0628a11f0cf874 > > > > I found a problem with the b43 implementation. The local variables for > > that routine includes > > > > u32 angle = 0; > > > > If one looks further down in the algorithm, if the reduced value of > > "theta" is less than 0, then "angle" should be negative. That causes > > the calculation to blow up. This explains why some ranges of angles > > got the same result for both routines. When that declaration is > > changed to "int angle = 0", the two routines give the same answer for > > all inputs. > > > > My test setup has a hardware failure, thus I cannot test your patch, > > but I now believe it to be correct. Thus your first and third patches > > may be annotated with > > ACKed-by: Larry Finger <Larry.Finger@lwfinger.net> > > > > One thing that should be done is to fix the error in the b43 code for > > stable as it was introduced in 2.6.34. I propose adding the attached > > patched to your series placed between your current 2nd and 3rd patches > > so that the old kernels get fixed. Of course, your 3rd patch will need > > to be revised. If all 4 of the patches get submitted together there > > will be no problems with the timing. My change will exist for seconds > > in the mainline kernel, but it will get propagated back through > > stable. > > Sorry Larry, I'm not fully understanding what you mean here. So I'm > going to just drop the whole series and assume that Priit will submit a > new version. Please let me know if I should do something else. Yes, drop this one and I will submit v4 with one extra patch fixing the cordic algorithm in the stable kernel. > > -- > Kalle Valo
On Sun, Nov 18, 2018 at 01:35:57PM -0600, Larry Finger wrote: > On 11/18/18 2:23 AM, Priit Laes wrote: > > On Sat, Nov 17, 2018 at 09:31:35PM -0600, Larry Finger wrote: > > > On 11/14/18 12:27 PM, Priit Laes wrote: > > > > Kernel library has a common cordic algorithm which is identical > > > > to internally implementatd one, so use it and drop the duplicate > > > > implementation. > > > > > > My test setup has a hardware failure, thus I cannot test your patch, but I > now believe it to be correct. Thus your first and third patches may be > annotated with > ACKed-by: Larry Finger <Larry.Finger@lwfinger.net> > > One thing that should be done is to fix the error in the b43 code for stable > as it was introduced in 2.6.34. I propose adding the attached patched to > your series placed between your current 2nd and 3rd patches so that the old > kernels get fixed. Of course, your 3rd patch will need to be revised. If all > 4 of the patches get submitted together there will be no problems with the > timing. My change will exist for seconds in the mainline kernel, but it will > get propagated back through stable. Thanks! > From b42ae73ef7505de93e4c66fb9f66930e3f3d969a Mon Sep 17 00:00:00 2001 > From: Larry Finger <Larry.Finger@lwfinger.net> > Date: Sun, 18 Nov 2018 13:15:07 -0600 > Subject: [PATCH] b43: Fix error in cordic routine > MIME-Version: 1.0 > Content-Type: text/plain; charset=UTF-8 > Content-Transfer-Encoding: 8bit > To: kvalo@codeaurora.org > Cc: linux-wireless@vger.kernel.org > > The cordic routine for calculating sines and cosines that was added in > commit 986504540306 ("b43: make cordic common (LP-PHY and N-PHY need it)") > contains an error whereby a quantity declared u32 can in fact go negative. It seems to be different commit though: commit 6f98e62a9 ("b43: update cordic code to match current specs") > This problem was detected by Priit Laes who is switching b43 to use the > routine in the library functions of the kernel. > > Fixes: 986504540306 ("b43: make cordic common (LP-PHY and N-PHY need it)") > Reported-by: Priit Laes <plaes@plaes.org> > Cc: Rafa?? Mi??ecki <zajec5@gmail.com> > Cc: Stable <stable@vger.kernel.org> # 2.6.34 > Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net> > --- > drivers/net/wireless/broadcom/b43/phy_common.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/net/wireless/broadcom/b43/phy_common.c b/drivers/net/wireless/broadcom/b43/phy_common.c > index 85f2ca989565..ef3ffa5ad466 100644 > --- a/drivers/net/wireless/broadcom/b43/phy_common.c > +++ b/drivers/net/wireless/broadcom/b43/phy_common.c > @@ -616,7 +616,7 @@ struct b43_c32 b43_cordic(int theta) > u8 i; > s32 tmp; > s8 signx = 1; > - u32 angle = 0; > + s32 angle = 0; > struct b43_c32 ret = { .i = 39797, .q = 0, }; > > while (theta > (180 << 16)) > -- > 2.16.4 >
On 11/19/18 5:27 AM, Priit Laes wrote: > On Sun, Nov 18, 2018 at 01:35:57PM -0600, Larry Finger wrote: >> On 11/18/18 2:23 AM, Priit Laes wrote: >>> On Sat, Nov 17, 2018 at 09:31:35PM -0600, Larry Finger wrote: >>>> On 11/14/18 12:27 PM, Priit Laes wrote: >>>>> Kernel library has a common cordic algorithm which is identical >>>>> to internally implementatd one, so use it and drop the duplicate >>>>> implementation. >>>>> >> >> My test setup has a hardware failure, thus I cannot test your patch, but I >> now believe it to be correct. Thus your first and third patches may be >> annotated with >> ACKed-by: Larry Finger <Larry.Finger@lwfinger.net> >> >> One thing that should be done is to fix the error in the b43 code for stable >> as it was introduced in 2.6.34. I propose adding the attached patched to >> your series placed between your current 2nd and 3rd patches so that the old >> kernels get fixed. Of course, your 3rd patch will need to be revised. If all >> 4 of the patches get submitted together there will be no problems with the >> timing. My change will exist for seconds in the mainline kernel, but it will >> get propagated back through stable. > > Thanks! > >> From b42ae73ef7505de93e4c66fb9f66930e3f3d969a Mon Sep 17 00:00:00 2001 >> From: Larry Finger <Larry.Finger@lwfinger.net> >> Date: Sun, 18 Nov 2018 13:15:07 -0600 >> Subject: [PATCH] b43: Fix error in cordic routine >> MIME-Version: 1.0 >> Content-Type: text/plain; charset=UTF-8 >> Content-Transfer-Encoding: 8bit >> To: kvalo@codeaurora.org >> Cc: linux-wireless@vger.kernel.org >> >> The cordic routine for calculating sines and cosines that was added in >> commit 986504540306 ("b43: make cordic common (LP-PHY and N-PHY need it)") >> contains an error whereby a quantity declared u32 can in fact go negative. > > It seems to be different commit though: > commit 6f98e62a9 ("b43: update cordic code to match current specs") Thanks for catching that mistake. I must have gotten one line off in my copy and paste. The respun version of my patch is attached. I have now been able to test b43 on an LP-PHY device. I do not see any major changes, but there has to be some effect. Larry Larry From b42ae73ef7505de93e4c66fb9f66930e3f3d969a Mon Sep 17 00:00:00 2001 From: Larry Finger <Larry.Finger@lwfinger.net> Date: Sun, 18 Nov 2018 13:15:07 -0600 Subject: [PATCH] b43: Fix error in cordic routine MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit To: kvalo@codeaurora.org Cc: linux-wireless@vger.kernel.org The cordic routine for calculating sines and cosines that was added in commit 6f98e62a9f1b ("b43: update cordic code to match current specs") contains an error whereby a quantity declared u32 can in fact go negative. This problem was detected by Priit Laes who is switching b43 to use the routine in the library functions of the kernel. Fixes: 6f98e62a9f1b ("b43: update cordic code to match current specs") Reported-by: Priit Laes <plaes@plaes.org> Cc: Rafał Miłecki <zajec5@gmail.com> Cc: Stable <stable@vger.kernel.org> # 2.6.34 Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net> --- drivers/net/wireless/broadcom/b43/phy_common.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/net/wireless/broadcom/b43/phy_common.c b/drivers/net/wireless/broadcom/b43/phy_common.c index 85f2ca989565..ef3ffa5ad466 100644 --- a/drivers/net/wireless/broadcom/b43/phy_common.c +++ b/drivers/net/wireless/broadcom/b43/phy_common.c @@ -616,7 +616,7 @@ struct b43_c32 b43_cordic(int theta) u8 i; s32 tmp; s8 signx = 1; - u32 angle = 0; + s32 angle = 0; struct b43_c32 ret = { .i = 39797, .q = 0, }; while (theta > (180 << 16))
On 11/19/18 4:43 AM, Kalle Valo wrote: > Larry Finger <Larry.Finger@lwfinger.net> writes: > >>>>> @@ -1570,10 +1571,10 @@ static u16 b43_nphy_gen_load_samples(struct b43_wldev *dev, u32 freq, u16 max, >>>>> angle = 0; >>>>> for (i = 0; i < len; i++) { >>>>> - samples[i] = b43_cordic(angle); >>>>> + samples[i] = cordic_calc_iq(angle); >>>>> angle += rot; >>>>> - samples[i].q = CORDIC_CONVERT(samples[i].q * max); >>>>> - samples[i].i = CORDIC_CONVERT(samples[i].i * max); >>>>> + samples[i].q = CORDIC_FLOAT(samples[i].q * max); >>>>> + samples[i].i = CORDIC_FLOAT(samples[i].i * max); >>>>> } >>>>> i = b43_nphy_load_samples(dev, samples, len); >>>> >>>> There is a fundamental flaw in this patch. Routine b43_cordic() takes an >>>> angle in degrees scaled by 2^16, whereas cordic_calc_iq() takes an angle in >>>> degrees. For a given input, the two routines must get different answers. At >>>> a minimum, the calculation of rot would need to remove the left shift of 16. >>> >>> Thanks for the hint. I modified my "test harness" a bit to plot out values >>> from -360 .. 360 and transformed the theta for b43_cordic argument >>> using CORDIC_FIXED macro: >>> >>> b43_cordic(CORDIC_FIXED(theta)); >>> cordic_calc_iq(theta); >>> >>> Then I plotted the results and well.. they are not that pretty. >>> While the results give >>> identical answers between certain ranges of degrees, the cordic >>> algorithm for b43 seems >>> to be broken for certain ranges: (-270..-180 ; -90 .. 0; 90.. 180 and 270..360). >>> >>> You can find my test harnesses here: >>> >>> https://gist.github.com/plaes/284993a4fc65e0926d0628a11f0cf874 >> >> I found a problem with the b43 implementation. The local variables for >> that routine includes >> >> u32 angle = 0; >> >> If one looks further down in the algorithm, if the reduced value of >> "theta" is less than 0, then "angle" should be negative. That causes >> the calculation to blow up. This explains why some ranges of angles >> got the same result for both routines. When that declaration is >> changed to "int angle = 0", the two routines give the same answer for >> all inputs. >> >> My test setup has a hardware failure, thus I cannot test your patch, >> but I now believe it to be correct. Thus your first and third patches >> may be annotated with >> ACKed-by: Larry Finger <Larry.Finger@lwfinger.net> >> >> One thing that should be done is to fix the error in the b43 code for >> stable as it was introduced in 2.6.34. I propose adding the attached >> patched to your series placed between your current 2nd and 3rd patches >> so that the old kernels get fixed. Of course, your 3rd patch will need >> to be revised. If all 4 of the patches get submitted together there >> will be no problems with the timing. My change will exist for seconds >> in the mainline kernel, but it will get propagated back through >> stable. > > Sorry Larry, I'm not fully understanding what you mean here. So I'm > going to just drop the whole series and assume that Priit will submit a > new version. Please let me know if I should do something else. Dropping the entire series is the right thing to do. The complication is that with Priit's changes, my fix is irrelevant for HEAD, but it is still needed for stable. My patch must be submitted before his 3rd one, but then his will not apply cleanly.If he respins his patches and puts mine in the series before he changes b43, then my patch will be available for stable even though his next patch will replace my new code. That seems to be the best approach. Larry
diff --git a/drivers/net/wireless/broadcom/b43/Kconfig b/drivers/net/wireless/broadcom/b43/Kconfig index fba8560..3e41457 100644 --- a/drivers/net/wireless/broadcom/b43/Kconfig +++ b/drivers/net/wireless/broadcom/b43/Kconfig @@ -4,6 +4,7 @@ config B43 select BCMA if B43_BCMA select SSB if B43_SSB select FW_LOADER + select CORDIC ---help--- b43 is a driver for the Broadcom 43xx series wireless devices. diff --git a/drivers/net/wireless/broadcom/b43/phy_common.c b/drivers/net/wireless/broadcom/b43/phy_common.c index 85f2ca9..98c4fa5 100644 --- a/drivers/net/wireless/broadcom/b43/phy_common.c +++ b/drivers/net/wireless/broadcom/b43/phy_common.c @@ -604,50 +604,3 @@ void b43_phy_force_clock(struct b43_wldev *dev, bool force) #endif } } - -/* http://bcm-v4.sipsolutions.net/802.11/PHY/Cordic */ -struct b43_c32 b43_cordic(int theta) -{ - static const u32 arctg[] = { - 2949120, 1740967, 919879, 466945, 234379, 117304, - 58666, 29335, 14668, 7334, 3667, 1833, - 917, 458, 229, 115, 57, 29, - }; - u8 i; - s32 tmp; - s8 signx = 1; - u32 angle = 0; - struct b43_c32 ret = { .i = 39797, .q = 0, }; - - while (theta > (180 << 16)) - theta -= (360 << 16); - while (theta < -(180 << 16)) - theta += (360 << 16); - - if (theta > (90 << 16)) { - theta -= (180 << 16); - signx = -1; - } else if (theta < -(90 << 16)) { - theta += (180 << 16); - signx = -1; - } - - for (i = 0; i <= 17; i++) { - if (theta > angle) { - tmp = ret.i - (ret.q >> i); - ret.q += ret.i >> i; - ret.i = tmp; - angle += arctg[i]; - } else { - tmp = ret.i + (ret.q >> i); - ret.q -= ret.i >> i; - ret.i = tmp; - angle -= arctg[i]; - } - } - - ret.i *= signx; - ret.q *= signx; - - return ret; -} diff --git a/drivers/net/wireless/broadcom/b43/phy_common.h b/drivers/net/wireless/broadcom/b43/phy_common.h index 57a1ad8..4213cac 100644 --- a/drivers/net/wireless/broadcom/b43/phy_common.h +++ b/drivers/net/wireless/broadcom/b43/phy_common.h @@ -7,13 +7,6 @@ struct b43_wldev; -/* Complex number using 2 32-bit signed integers */ -struct b43_c32 { s32 i, q; }; - -#define CORDIC_CONVERT(value) (((value) >= 0) ? \ - ((((value) >> 15) + 1) >> 1) : \ - -((((-(value)) >> 15) + 1) >> 1)) - /* PHY register routing bits */ #define B43_PHYROUTE 0x0C00 /* PHY register routing bits mask */ #define B43_PHYROUTE_BASE 0x0000 /* Base registers */ @@ -450,6 +443,4 @@ bool b43_is_40mhz(struct b43_wldev *dev); void b43_phy_force_clock(struct b43_wldev *dev, bool force); -struct b43_c32 b43_cordic(int theta); - #endif /* LINUX_B43_PHY_COMMON_H_ */ diff --git a/drivers/net/wireless/broadcom/b43/phy_lp.c b/drivers/net/wireless/broadcom/b43/phy_lp.c index 6922cbb..1718e3b 100644 --- a/drivers/net/wireless/broadcom/b43/phy_lp.c +++ b/drivers/net/wireless/broadcom/b43/phy_lp.c @@ -23,6 +23,7 @@ */ +#include <linux/cordic.h> #include <linux/slab.h> #include "b43.h" @@ -1780,9 +1781,9 @@ static void lpphy_start_tx_tone(struct b43_wldev *dev, s32 freq, u16 max) { struct b43_phy_lp *lpphy = dev->phy.lp; u16 buf[64]; - int i, samples = 0, angle = 0; + int i, samples = 0, theta = 0; int rotation = (((36 * freq) / 20) << 16) / 100; - struct b43_c32 sample; + struct cordic_iq sample; lpphy->tx_tone_freq = freq; @@ -1798,10 +1799,10 @@ static void lpphy_start_tx_tone(struct b43_wldev *dev, s32 freq, u16 max) } for (i = 0; i < samples; i++) { - sample = b43_cordic(angle); - angle += rotation; - buf[i] = CORDIC_CONVERT((sample.i * max) & 0xFF) << 8; - buf[i] |= CORDIC_CONVERT((sample.q * max) & 0xFF); + sample = cordic_calc_iq(theta); + theta += rotation; + buf[i] = CORDIC_FLOAT((sample.i * max) & 0xFF) << 8; + buf[i] |= CORDIC_FLOAT((sample.q * max) & 0xFF); } b43_lptab_write_bulk(dev, B43_LPTAB16(5, 0), samples, buf); diff --git a/drivers/net/wireless/broadcom/b43/phy_n.c b/drivers/net/wireless/broadcom/b43/phy_n.c index 44ab080..1f9378a 100644 --- a/drivers/net/wireless/broadcom/b43/phy_n.c +++ b/drivers/net/wireless/broadcom/b43/phy_n.c @@ -23,6 +23,7 @@ */ +#include <linux/cordic.h> #include <linux/delay.h> #include <linux/slab.h> #include <linux/types.h> @@ -1513,7 +1514,7 @@ static void b43_radio_init2055(struct b43_wldev *dev) /* http://bcm-v4.sipsolutions.net/802.11/PHY/N/LoadSampleTable */ static int b43_nphy_load_samples(struct b43_wldev *dev, - struct b43_c32 *samples, u16 len) { + struct cordic_iq *samples, u16 len) { struct b43_phy_n *nphy = dev->phy.n; u16 i; u32 *data; @@ -1544,7 +1545,7 @@ static u16 b43_nphy_gen_load_samples(struct b43_wldev *dev, u32 freq, u16 max, { int i; u16 bw, len, rot, angle; - struct b43_c32 *samples; + struct cordic_iq *samples; bw = b43_is_40mhz(dev) ? 40 : 20; len = bw << 3; @@ -1561,7 +1562,7 @@ static u16 b43_nphy_gen_load_samples(struct b43_wldev *dev, u32 freq, u16 max, len = bw << 1; } - samples = kcalloc(len, sizeof(struct b43_c32), GFP_KERNEL); + samples = kcalloc(len, sizeof(struct cordic_iq), GFP_KERNEL); if (!samples) { b43err(dev->wl, "allocation for samples generation failed\n"); return 0; @@ -1570,10 +1571,10 @@ static u16 b43_nphy_gen_load_samples(struct b43_wldev *dev, u32 freq, u16 max, angle = 0; for (i = 0; i < len; i++) { - samples[i] = b43_cordic(angle); + samples[i] = cordic_calc_iq(angle); angle += rot; - samples[i].q = CORDIC_CONVERT(samples[i].q * max); - samples[i].i = CORDIC_CONVERT(samples[i].i * max); + samples[i].q = CORDIC_FLOAT(samples[i].q * max); + samples[i].i = CORDIC_FLOAT(samples[i].i * max); } i = b43_nphy_load_samples(dev, samples, len);
Kernel library has a common cordic algorithm which is identical to internally implementatd one, so use it and drop the duplicate implementation. Signed-off-by: Priit Laes <plaes@plaes.org> --- drivers/net/wireless/broadcom/b43/Kconfig | 1 +- drivers/net/wireless/broadcom/b43/phy_common.c | 47 +------------------- drivers/net/wireless/broadcom/b43/phy_common.h | 9 +---- drivers/net/wireless/broadcom/b43/phy_lp.c | 13 ++--- drivers/net/wireless/broadcom/b43/phy_n.c | 13 ++--- 5 files changed, 15 insertions(+), 68 deletions(-)