| Message ID | 1348652877-25816-5-git-send-email-javier.martin@vista-silicon.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Wed, 26 Sep 2012 11:47:56 +0200 Javier Martin <javier.martin@vista-silicon.com> wrote: > > Signed-off-by: Javier Martin <javier.martin@vista-silicon.com> This one needs a changelog - what does bypassing the PLL do and why might you want to do it? Otherwise: Acked-by: Jonathan Corbet <corbet@lwn.net> jon -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 26 September 2012 18:52, Jonathan Corbet <corbet@lwn.net> wrote: > On Wed, 26 Sep 2012 11:47:56 +0200 > Javier Martin <javier.martin@vista-silicon.com> wrote: > >> >> Signed-off-by: Javier Martin <javier.martin@vista-silicon.com> > > This one needs a changelog - what does bypassing the PLL do and why might > you want to do it? Otherwise: As I stated in a previous patch, frame rate depends on the pixclk. Moreover: pixclk = xvclk / clkrc * PLLfactor Bypassing the PLL means that the PLL gets out of the way so, in practice, PLLfactor = 1 pixclk = xvclk / clkrc For a frame rate of 30 fps a pixclk of 24MHz is needed. Since we have a clean clock signal we want pixclk = xvclk. If one applies the formula in ov7670_set_framerate() with PLLfactor = 1 and clock_speed = 24 MHz the resulting clkrc = 1 which means that: pixclk = xvclk which is what we want > Acked-by: Jonathan Corbet <corbet@lwn.net> Thank you. I will add a changelog when I send v2 of the series. Regards.
diff --git a/drivers/media/i2c/ov7670.c b/drivers/media/i2c/ov7670.c index 175fbfc..54fb535 100644 --- a/drivers/media/i2c/ov7670.c +++ b/drivers/media/i2c/ov7670.c @@ -210,6 +210,7 @@ struct ov7670_info { int clock_speed; /* External clock speed (MHz) */ u8 clkrc; /* Clock divider value */ bool use_smbus; /* Use smbus I/O instead of I2C */ + bool pll_bypass; enum ov7670_model model; }; @@ -778,7 +779,12 @@ static void ov7670_get_framerate(struct v4l2_subdev *sd, { struct ov7670_info *info = to_state(sd); u32 clkrc = info->clkrc; - u32 pll_factor = PLL_FACTOR; + int pll_factor; + + if (info->pll_bypass) + pll_factor = 1; + else + pll_factor = PLL_FACTOR; clkrc++; if (info->fmt->mbus_code == V4L2_MBUS_FMT_SBGGR8_1X8) @@ -794,7 +800,7 @@ static int ov7670_set_framerate(struct v4l2_subdev *sd, { struct ov7670_info *info = to_state(sd); u32 clkrc; - u32 pll_factor = PLL_FACTOR; + int pll_factor; int ret; /* @@ -804,6 +810,16 @@ static int ov7670_set_framerate(struct v4l2_subdev *sd, * pixclk = clock_speed / (clkrc + 1) * PLLfactor * */ + if (info->pll_bypass) { + pll_factor = 1; + ret = ov7670_write(sd, REG_DBLV, DBLV_BYPASS); + } else { + pll_factor = PLL_FACTOR; + ret = ov7670_write(sd, REG_DBLV, DBLV_X4); + } + if (ret < 0) + return ret; + if (tpf->numerator == 0 || tpf->denominator == 0) { clkrc = 0; } else { @@ -831,6 +847,7 @@ static int ov7670_set_framerate(struct v4l2_subdev *sd, ret = ov7670_write(sd, REG_CLKRC, info->clkrc); if (ret < 0) return ret; + return ov7670_write(sd, REG_DBLV, DBLV_X4); } @@ -1689,6 +1706,9 @@ static int ov7670_probe(struct i2c_client *client, if (config->clock_speed) info->clock_speed = config->clock_speed; + + if (config->pll_bypass && id->driver_data != MODEL_OV7670) + info->pll_bypass = true; } /* Make sure it's an ov7670 */ diff --git a/include/media/ov7670.h b/include/media/ov7670.h index b133bc1..a68c8bb 100644 --- a/include/media/ov7670.h +++ b/include/media/ov7670.h @@ -15,6 +15,7 @@ struct ov7670_config { int min_height; /* Filter out smaller sizes */ int clock_speed; /* External clock speed (MHz) */ bool use_smbus; /* Use smbus I/O instead of I2C */ + bool pll_bypass; /* Choose whether to bypass the PLL */ }; #endif
Signed-off-by: Javier Martin <javier.martin@vista-silicon.com> --- drivers/media/i2c/ov7670.c | 24 ++++++++++++++++++++++-- include/media/ov7670.h | 1 + 2 files changed, 23 insertions(+), 2 deletions(-)