| Message ID | 20210111174616.904674-1-giulio.benetti@benettiengineering.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v3] drm/sun4i: tcon: fix inverted DCLK polarity | expand |
Hi, On Mon, Jan 11, 2021 at 06:46:16PM +0100, Giulio Benetti wrote: > From: Giulio Benetti <giulio.benetti@micronovasrl.com> > > During commit 88bc4178568b ("drm: Use new > DRM_BUS_FLAG_*_(DRIVE|SAMPLE)_(POS|NEG)EDGE flags") DRM_BUS_FLAG_* > macros have been changed to avoid ambiguity but just because of this > ambiguity previous DRM_BUS_FLAG_PIXDATA_(POS/NEG)EDGE were used meaning > _SAMPLE_ not _DRIVE_. This leads to DLCK inversion and need to fix but > instead of swapping phase values, let's adopt an easier approach Maxime > suggested: > It turned out that bit 26 of SUN4I_TCON0_IO_POL_REG is dedicated to > invert DCLK polarity and this makes things really easier than before. So > let's handle DCLK polarity by adding SUN4I_TCON0_IO_POL_DCLK_POSITIVE as > bit 26 and activating according to bus_flags the same way it is done for > all the other signals polarity. > > Fixes: 88bc4178568b ("drm: Use new DRM_BUS_FLAG_*_(DRIVE|SAMPLE)_(POS|NEG)EDGE flags") > Suggested-by: Maxime Ripard <maxime@cerno.tech> > Signed-off-by: Giulio Benetti <giulio.benetti@micronovasrl.com> > --- > drivers/gpu/drm/sun4i/sun4i_tcon.c | 20 +------------------- > drivers/gpu/drm/sun4i/sun4i_tcon.h | 1 + > 2 files changed, 2 insertions(+), 19 deletions(-) > > diff --git a/drivers/gpu/drm/sun4i/sun4i_tcon.c b/drivers/gpu/drm/sun4i/sun4i_tcon.c > index eaaf5d70e352..30171ccd87e5 100644 > --- a/drivers/gpu/drm/sun4i/sun4i_tcon.c > +++ b/drivers/gpu/drm/sun4i/sun4i_tcon.c > @@ -569,26 +569,8 @@ static void sun4i_tcon0_mode_set_rgb(struct sun4i_tcon *tcon, > if (info->bus_flags & DRM_BUS_FLAG_DE_LOW) > val |= SUN4I_TCON0_IO_POL_DE_NEGATIVE; > > - /* > - * On A20 and similar SoCs, the only way to achieve Positive Edge > - * (Rising Edge), is setting dclk clock phase to 2/3(240°). > - * By default TCON works in Negative Edge(Falling Edge), > - * this is why phase is set to 0 in that case. > - * Unfortunately there's no way to logically invert dclk through > - * IO_POL register. > - * The only acceptable way to work, triple checked with scope, > - * is using clock phase set to 0° for Negative Edge and set to 240° > - * for Positive Edge. > - * On A33 and similar SoCs there would be a 90° phase option, > - * but it divides also dclk by 2. > - * Following code is a way to avoid quirks all around TCON > - * and DOTCLOCK drivers. > - */ > if (info->bus_flags & DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE) > - clk_set_phase(tcon->dclk, 240); > - > - if (info->bus_flags & DRM_BUS_FLAG_PIXDATA_DRIVE_NEGEDGE) > - clk_set_phase(tcon->dclk, 0); > + val |= SUN4I_TCON0_IO_POL_DCLK_POSITIVE; > > regmap_update_bits(tcon->regs, SUN4I_TCON0_IO_POL_REG, > SUN4I_TCON0_IO_POL_HSYNC_POSITIVE | You need to add SUN4I_TCON0_IO_POL_DCLK_POSITIVE to the mask you're going to change here too Maxime
On 1/13/21 10:42 AM, Maxime Ripard wrote: > Hi, > > On Mon, Jan 11, 2021 at 06:46:16PM +0100, Giulio Benetti wrote: >> From: Giulio Benetti <giulio.benetti@micronovasrl.com> >> >> During commit 88bc4178568b ("drm: Use new >> DRM_BUS_FLAG_*_(DRIVE|SAMPLE)_(POS|NEG)EDGE flags") DRM_BUS_FLAG_* >> macros have been changed to avoid ambiguity but just because of this >> ambiguity previous DRM_BUS_FLAG_PIXDATA_(POS/NEG)EDGE were used meaning >> _SAMPLE_ not _DRIVE_. This leads to DLCK inversion and need to fix but >> instead of swapping phase values, let's adopt an easier approach Maxime >> suggested: >> It turned out that bit 26 of SUN4I_TCON0_IO_POL_REG is dedicated to >> invert DCLK polarity and this makes things really easier than before. So >> let's handle DCLK polarity by adding SUN4I_TCON0_IO_POL_DCLK_POSITIVE as >> bit 26 and activating according to bus_flags the same way it is done for >> all the other signals polarity. >> >> Fixes: 88bc4178568b ("drm: Use new DRM_BUS_FLAG_*_(DRIVE|SAMPLE)_(POS|NEG)EDGE flags") >> Suggested-by: Maxime Ripard <maxime@cerno.tech> >> Signed-off-by: Giulio Benetti <giulio.benetti@micronovasrl.com> >> --- >> drivers/gpu/drm/sun4i/sun4i_tcon.c | 20 +------------------- >> drivers/gpu/drm/sun4i/sun4i_tcon.h | 1 + >> 2 files changed, 2 insertions(+), 19 deletions(-) >> >> diff --git a/drivers/gpu/drm/sun4i/sun4i_tcon.c b/drivers/gpu/drm/sun4i/sun4i_tcon.c >> index eaaf5d70e352..30171ccd87e5 100644 >> --- a/drivers/gpu/drm/sun4i/sun4i_tcon.c >> +++ b/drivers/gpu/drm/sun4i/sun4i_tcon.c >> @@ -569,26 +569,8 @@ static void sun4i_tcon0_mode_set_rgb(struct sun4i_tcon *tcon, >> if (info->bus_flags & DRM_BUS_FLAG_DE_LOW) >> val |= SUN4I_TCON0_IO_POL_DE_NEGATIVE; >> >> - /* >> - * On A20 and similar SoCs, the only way to achieve Positive Edge >> - * (Rising Edge), is setting dclk clock phase to 2/3(240°). >> - * By default TCON works in Negative Edge(Falling Edge), >> - * this is why phase is set to 0 in that case. >> - * Unfortunately there's no way to logically invert dclk through >> - * IO_POL register. >> - * The only acceptable way to work, triple checked with scope, >> - * is using clock phase set to 0° for Negative Edge and set to 240° >> - * for Positive Edge. >> - * On A33 and similar SoCs there would be a 90° phase option, >> - * but it divides also dclk by 2. >> - * Following code is a way to avoid quirks all around TCON >> - * and DOTCLOCK drivers. >> - */ >> if (info->bus_flags & DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE) >> - clk_set_phase(tcon->dclk, 240); >> - >> - if (info->bus_flags & DRM_BUS_FLAG_PIXDATA_DRIVE_NEGEDGE) >> - clk_set_phase(tcon->dclk, 0); >> + val |= SUN4I_TCON0_IO_POL_DCLK_POSITIVE; >> >> regmap_update_bits(tcon->regs, SUN4I_TCON0_IO_POL_REG, >> SUN4I_TCON0_IO_POL_HSYNC_POSITIVE | > > You need to add SUN4I_TCON0_IO_POL_DCLK_POSITIVE to the mask you're > going to change here too Ah, lost it during squash, I send a v4. Thank you Best regards
diff --git a/drivers/gpu/drm/sun4i/sun4i_tcon.c b/drivers/gpu/drm/sun4i/sun4i_tcon.c index eaaf5d70e352..30171ccd87e5 100644 --- a/drivers/gpu/drm/sun4i/sun4i_tcon.c +++ b/drivers/gpu/drm/sun4i/sun4i_tcon.c @@ -569,26 +569,8 @@ static void sun4i_tcon0_mode_set_rgb(struct sun4i_tcon *tcon, if (info->bus_flags & DRM_BUS_FLAG_DE_LOW) val |= SUN4I_TCON0_IO_POL_DE_NEGATIVE; - /* - * On A20 and similar SoCs, the only way to achieve Positive Edge - * (Rising Edge), is setting dclk clock phase to 2/3(240°). - * By default TCON works in Negative Edge(Falling Edge), - * this is why phase is set to 0 in that case. - * Unfortunately there's no way to logically invert dclk through - * IO_POL register. - * The only acceptable way to work, triple checked with scope, - * is using clock phase set to 0° for Negative Edge and set to 240° - * for Positive Edge. - * On A33 and similar SoCs there would be a 90° phase option, - * but it divides also dclk by 2. - * Following code is a way to avoid quirks all around TCON - * and DOTCLOCK drivers. - */ if (info->bus_flags & DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE) - clk_set_phase(tcon->dclk, 240); - - if (info->bus_flags & DRM_BUS_FLAG_PIXDATA_DRIVE_NEGEDGE) - clk_set_phase(tcon->dclk, 0); + val |= SUN4I_TCON0_IO_POL_DCLK_POSITIVE; regmap_update_bits(tcon->regs, SUN4I_TCON0_IO_POL_REG, SUN4I_TCON0_IO_POL_HSYNC_POSITIVE | diff --git a/drivers/gpu/drm/sun4i/sun4i_tcon.h b/drivers/gpu/drm/sun4i/sun4i_tcon.h index cfbf4e6c1679..0ce71d10a31b 100644 --- a/drivers/gpu/drm/sun4i/sun4i_tcon.h +++ b/drivers/gpu/drm/sun4i/sun4i_tcon.h @@ -113,6 +113,7 @@ #define SUN4I_TCON0_IO_POL_REG 0x88 #define SUN4I_TCON0_IO_POL_DCLK_PHASE(phase) ((phase & 3) << 28) #define SUN4I_TCON0_IO_POL_DE_NEGATIVE BIT(27) +#define SUN4I_TCON0_IO_POL_DCLK_POSITIVE BIT(26) #define SUN4I_TCON0_IO_POL_HSYNC_POSITIVE BIT(25) #define SUN4I_TCON0_IO_POL_VSYNC_POSITIVE BIT(24)