| Message ID | 1640768259-18070-1-git-send-email-bingbu.cao@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | media: ov5675: use group write to update digital gain | expand |
Hi Bingbu, On Wed, Dec 29, 2021 at 04:57:39PM +0800, Bingbu Cao wrote: > MWB gain register are used to set gain for each mwb channel mannually. > However, it will involve some artifacts at low light environment as gain > cannot be applied to each channel synchronously. Update the driver to use > group write for digital gain to make the sure RGB digital gain be applied > together at frame boundary. How about the analogue gain and exposure time? Shouldn't they be applied similarly as well? Adding two more writes increases the probability of missing a frame there. This is of course a trick since the control framework doesn't really support this, but I think this support should be added.
Hi Sakari, Thanks for your review.
On Wed, Dec 29, 2021 at 10:00:43AM +0000, Cao, Bingbu wrote: > Hi Sakari, > > Thanks for your review. > > ________________________ > BRs, > Bingbu Cao > > > -----Original Message----- > > From: Sakari Ailus <sakari.ailus@linux.intel.com> > > Sent: Wednesday, December 29, 2021 5:42 PM > > To: Cao, Bingbu <bingbu.cao@intel.com> > > Cc: linux-media@vger.kernel.org; Tu, ShawnX <shawnx.tu@intel.com>; > > senozhatsky@chromium.org; tfiga@chromium.org; bingbu.cao@linux.intel.com; > > Yeh, Andy <andy.yeh@intel.com> > > Subject: Re: [PATCH] media: ov5675: use group write to update digital > > gain > > > > Hi Bingbu, > > > > On Wed, Dec 29, 2021 at 04:57:39PM +0800, Bingbu Cao wrote: > > > MWB gain register are used to set gain for each mwb channel mannually. > > > However, it will involve some artifacts at low light environment as > > > gain cannot be applied to each channel synchronously. Update the > > > driver to use group write for digital gain to make the sure RGB > > > digital gain be applied together at frame boundary. > > > > How about the analogue gain and exposure time? > > > > Shouldn't they be applied similarly as well? Adding two more writes > > increases the probability of missing a frame there. > > We did not meet issue related to analog gain as the it was applied by only > 1 reg write, it looks like same issue we found on ov8856, changing to set > digital gain by only 1 global gain write will fix the problem. That device is different in its support for global digital gain. This patch sets the gain for each component separately. Adding more writes on a given frame increases the probability of slipping to the following frame. Doing the exposure and gain updates in the same group write would alleviate that a little. > > > > > This is of course a trick since the control framework doesn't really > > support this, but I think this support should be added. > > > > -- > > Regards, > > > > Sakari Ailus
On 1/10/22 7:32 PM, Sakari Ailus wrote: > On Wed, Dec 29, 2021 at 10:00:43AM +0000, Cao, Bingbu wrote: >> Hi Sakari, >> >> Thanks for your review. >> >> ________________________ >> BRs, >> Bingbu Cao >> >>> -----Original Message----- >>> From: Sakari Ailus <sakari.ailus@linux.intel.com> >>> Sent: Wednesday, December 29, 2021 5:42 PM >>> To: Cao, Bingbu <bingbu.cao@intel.com> >>> Cc: linux-media@vger.kernel.org; Tu, ShawnX <shawnx.tu@intel.com>; >>> senozhatsky@chromium.org; tfiga@chromium.org; bingbu.cao@linux.intel.com; >>> Yeh, Andy <andy.yeh@intel.com> >>> Subject: Re: [PATCH] media: ov5675: use group write to update digital >>> gain >>> >>> Hi Bingbu, >>> >>> On Wed, Dec 29, 2021 at 04:57:39PM +0800, Bingbu Cao wrote: >>>> MWB gain register are used to set gain for each mwb channel mannually. >>>> However, it will involve some artifacts at low light environment as >>>> gain cannot be applied to each channel synchronously. Update the >>>> driver to use group write for digital gain to make the sure RGB >>>> digital gain be applied together at frame boundary. >>> >>> How about the analogue gain and exposure time? >>> >>> Shouldn't they be applied similarly as well? Adding two more writes >>> increases the probability of missing a frame there. >> >> We did not meet issue related to analog gain as the it was applied by only >> 1 reg write, it looks like same issue we found on ov8856, changing to set >> digital gain by only 1 global gain write will fix the problem. > > That device is different in its support for global digital gain. This patch > sets the gain for each component separately. > > Adding more writes on a given frame increases the probability of slipping > to the following frame. Doing the exposure and gain updates in the same > group write would alleviate that a little. Sakari, It is feasible to put the exposure and gain update in a same group, however, lunching the group at different time may increase the probability of slipping as well. What do you think? > >> >>> >>> This is of course a trick since the control framework doesn't really >>> support this, but I think this support should be added. >>> >>> -- >>> Regards, >>> >>> Sakari Ailus >
Hi Sakari, On Mon, Jan 10, 2022 at 8:32 PM Sakari Ailus <sakari.ailus@linux.intel.com> wrote: > > On Wed, Dec 29, 2021 at 10:00:43AM +0000, Cao, Bingbu wrote: > > Hi Sakari, > > > > Thanks for your review. > > > > ________________________ > > BRs, > > Bingbu Cao > > > > > -----Original Message----- > > > From: Sakari Ailus <sakari.ailus@linux.intel.com> > > > Sent: Wednesday, December 29, 2021 5:42 PM > > > To: Cao, Bingbu <bingbu.cao@intel.com> > > > Cc: linux-media@vger.kernel.org; Tu, ShawnX <shawnx.tu@intel.com>; > > > senozhatsky@chromium.org; tfiga@chromium.org; bingbu.cao@linux.intel.com; > > > Yeh, Andy <andy.yeh@intel.com> > > > Subject: Re: [PATCH] media: ov5675: use group write to update digital > > > gain > > > > > > Hi Bingbu, > > > > > > On Wed, Dec 29, 2021 at 04:57:39PM +0800, Bingbu Cao wrote: > > > > MWB gain register are used to set gain for each mwb channel mannually. > > > > However, it will involve some artifacts at low light environment as > > > > gain cannot be applied to each channel synchronously. Update the > > > > driver to use group write for digital gain to make the sure RGB > > > > digital gain be applied together at frame boundary. > > > > > > How about the analogue gain and exposure time? > > > > > > Shouldn't they be applied similarly as well? Adding two more writes > > > increases the probability of missing a frame there. > > > > We did not meet issue related to analog gain as the it was applied by only > > 1 reg write, it looks like same issue we found on ov8856, changing to set > > digital gain by only 1 global gain write will fix the problem. > > That device is different in its support for global digital gain. This patch > sets the gain for each component separately. That's not what the patch does. The existing code programs the 3 per-component registers separately. This patch made it happen under one write group. It doesn't increase the likelihood of the frame having wrong parameters - given the same timeline, before this patch, the frame would just have an even worse, partial gain setting, while with this patch it can either have the old or new gain. Best regards, Tomasz > > Adding more writes on a given frame increases the probability of slipping > to the following frame. Doing the exposure and gain updates in the same > group write would alleviate that a little. > > > > > > > > > This is of course a trick since the control framework doesn't really > > > support this, but I think this support should be added. > > > > > > -- > > > Regards, > > > > > > Sakari Ailus > > -- > Sakari Ailus
Sakari, I agree with Tomasz, the group write will not cause timing issues, instead it will help on that. So we did not need to group hold exposure and digital gain along with analog gain. Driver can not make the policy that the exposure, a-gain and d-gain are applied together. On 1/11/22 12:27 PM, Tomasz Figa wrote: > Hi Sakari, > > On Mon, Jan 10, 2022 at 8:32 PM Sakari Ailus > <sakari.ailus@linux.intel.com> wrote: >> >> On Wed, Dec 29, 2021 at 10:00:43AM +0000, Cao, Bingbu wrote: >>> Hi Sakari, >>> >>> Thanks for your review. >>> >>> ________________________ >>> BRs, >>> Bingbu Cao >>> >>>> -----Original Message----- >>>> From: Sakari Ailus <sakari.ailus@linux.intel.com> >>>> Sent: Wednesday, December 29, 2021 5:42 PM >>>> To: Cao, Bingbu <bingbu.cao@intel.com> >>>> Cc: linux-media@vger.kernel.org; Tu, ShawnX <shawnx.tu@intel.com>; >>>> senozhatsky@chromium.org; tfiga@chromium.org; bingbu.cao@linux.intel.com; >>>> Yeh, Andy <andy.yeh@intel.com> >>>> Subject: Re: [PATCH] media: ov5675: use group write to update digital >>>> gain >>>> >>>> Hi Bingbu, >>>> >>>> On Wed, Dec 29, 2021 at 04:57:39PM +0800, Bingbu Cao wrote: >>>>> MWB gain register are used to set gain for each mwb channel mannually. >>>>> However, it will involve some artifacts at low light environment as >>>>> gain cannot be applied to each channel synchronously. Update the >>>>> driver to use group write for digital gain to make the sure RGB >>>>> digital gain be applied together at frame boundary. >>>> >>>> How about the analogue gain and exposure time? >>>> >>>> Shouldn't they be applied similarly as well? Adding two more writes >>>> increases the probability of missing a frame there. >>> >>> We did not meet issue related to analog gain as the it was applied by only >>> 1 reg write, it looks like same issue we found on ov8856, changing to set >>> digital gain by only 1 global gain write will fix the problem. >> >> That device is different in its support for global digital gain. This patch >> sets the gain for each component separately. > > That's not what the patch does. The existing code programs the 3 > per-component registers separately. This patch made it happen under > one write group. It doesn't increase the likelihood of the frame > having wrong parameters - given the same timeline, before this patch, > the frame would just have an even worse, partial gain setting, while > with this patch it can either have the old or new gain. > > Best regards, > Tomasz > >> >> Adding more writes on a given frame increases the probability of slipping >> to the following frame. Doing the exposure and gain updates in the same >> group write would alleviate that a little. >> >>> >>>> >>>> This is of course a trick since the control framework doesn't really >>>> support this, but I think this support should be added. >>>> >>>> -- >>>> Regards, >>>> >>>> Sakari Ailus >> >> -- >> Sakari Ailus
Hi Bingbu, On Thu, Jan 27, 2022 at 11:14:56AM +0800, Bingbu Cao wrote: > Sakari, > > I agree with Tomasz, the group write will not cause timing issues, instead it will help > on that. So we did not need to group hold exposure and digital gain along with analog > gain. Driver can not make the policy that the exposure, a-gain and d-gain are applied > together. I'll take the patch but we're leaving some technical debt here, admittedly much of which was there to begin with. Please wrap before 80.
diff --git a/drivers/media/i2c/ov5675.c b/drivers/media/i2c/ov5675.c index 00925850fa7c..82ba9f56baec 100644 --- a/drivers/media/i2c/ov5675.c +++ b/drivers/media/i2c/ov5675.c @@ -50,14 +50,21 @@ #define OV5675_ANAL_GAIN_STEP 1 /* Digital gain controls from sensor */ +#define OV5675_REG_DIGITAL_GAIN 0x350a #define OV5675_REG_MWB_R_GAIN 0x5019 #define OV5675_REG_MWB_G_GAIN 0x501b #define OV5675_REG_MWB_B_GAIN 0x501d -#define OV5675_DGTL_GAIN_MIN 0 +#define OV5675_DGTL_GAIN_MIN 1024 #define OV5675_DGTL_GAIN_MAX 4095 #define OV5675_DGTL_GAIN_STEP 1 #define OV5675_DGTL_GAIN_DEFAULT 1024 +/* Group Access */ +#define OV5675_REG_GROUP_ACCESS 0x3208 +#define OV5675_GROUP_HOLD_START 0x0 +#define OV5675_GROUP_HOLD_END 0x10 +#define OV5675_GROUP_HOLD_LAUNCH 0xa0 + /* Test Pattern Control */ #define OV5675_REG_TEST_PATTERN 0x4503 #define OV5675_TEST_PATTERN_ENABLE BIT(7) @@ -587,6 +594,12 @@ static int ov5675_update_digital_gain(struct ov5675 *ov5675, u32 d_gain) { int ret; + ret = ov5675_write_reg(ov5675, OV5675_REG_GROUP_ACCESS, + OV5675_REG_VALUE_08BIT, + OV5675_GROUP_HOLD_START); + if (ret) + return ret; + ret = ov5675_write_reg(ov5675, OV5675_REG_MWB_R_GAIN, OV5675_REG_VALUE_16BIT, d_gain); if (ret) @@ -597,8 +610,21 @@ static int ov5675_update_digital_gain(struct ov5675 *ov5675, u32 d_gain) if (ret) return ret; - return ov5675_write_reg(ov5675, OV5675_REG_MWB_B_GAIN, - OV5675_REG_VALUE_16BIT, d_gain); + ret = ov5675_write_reg(ov5675, OV5675_REG_MWB_B_GAIN, + OV5675_REG_VALUE_16BIT, d_gain); + if (ret) + return ret; + + ret = ov5675_write_reg(ov5675, OV5675_REG_GROUP_ACCESS, + OV5675_REG_VALUE_08BIT, + OV5675_GROUP_HOLD_END); + if (ret) + return ret; + + ret = ov5675_write_reg(ov5675, OV5675_REG_GROUP_ACCESS, + OV5675_REG_VALUE_08BIT, + OV5675_GROUP_HOLD_LAUNCH); + return ret; } static int ov5675_test_pattern(struct ov5675 *ov5675, u32 pattern)
MWB gain register are used to set gain for each mwb channel mannually. However, it will involve some artifacts at low light environment as gain cannot be applied to each channel synchronously. Update the driver to use group write for digital gain to make the sure RGB digital gain be applied together at frame boundary. Signed-off-by: Bingbu Cao <bingbu.cao@intel.com> --- drivers/media/i2c/ov5675.c | 32 +++++++++++++++++++++++++++++--- 1 file changed, 29 insertions(+), 3 deletions(-)