RE: [PATCH 4/5] ispccdc: Configure CCDC_SYN_MODE register forUYVY8_2X8 and YUYV8_2X8 formats

[Ravi, Deepthy]

> ________________________________________
> From: Laurent Pinchart [laurent.pinchart@xxxxxxxxxxxxxxxx]
> Sent: Wednesday, September 21, 2011 2:36 PM
> To: Ravi, Deepthy
> Cc: mchehab@xxxxxxxxxxxxx; tony@xxxxxxxxxxx; Hiremath, Vaibhav; linux-media@xxxxxxxxxxxxxxx; linux@xxxxxxxxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; kyungmin.park@xxxxxxxxxxx; hverkuil@xxxxxxxxx; m.szyprowski@xxxxxxxxxxx; g.liakhovetski@xxxxxx; Shilimkar, Santosh; khilman@xxxxxxxxxxxxxxxxxxx; david.woodhouse@xxxxxxxxx; akpm@xxxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; linux-omap@xxxxxxxxxxxxxxx; Sakari Ailus
> Subject: Re: [PATCH 4/5] ispccdc: Configure CCDC_SYN_MODE register for UYVY8_2X8 and YUYV8_2X8 formats
>
> Hi Deepthy,
>
> On Wednesday 21 September 2011 07:32:44 Ravi, Deepthy wrote:
>> On Wednesday, September 21, 2011 4:56 AM Laurent Pinchart wrote:
>> > On Tuesday 20 September 2011 16:56:51 Deepthy Ravi wrote:
>> >> Configure INPMOD and PACK8 fileds of CCDC_SYN_MODE
>> >> register for UYVY8_2X8 and YUYV8_2X8 formats.
>> >>
>> >> Signed-off-by: Deepthy Ravi <deepthy.ravi@xxxxxx>
>> >> ---
>> >>
>> >>  drivers/media/video/omap3isp/ispccdc.c |   11 ++++++++---
>> >>  1 files changed, 8 insertions(+), 3 deletions(-)
>> >>
>> >> diff --git a/drivers/media/video/omap3isp/ispccdc.c
>> >> b/drivers/media/video/omap3isp/ispccdc.c index 418ba65..1dcf180 100644
>> >> --- a/drivers/media/video/omap3isp/ispccdc.c
>> >> +++ b/drivers/media/video/omap3isp/ispccdc.c
>> >> @@ -985,8 +985,12 @@ static void ccdc_config_sync_if(struct
>> >> isp_ccdc_device
>> >> *ccdc,
>> >>
>> >>       syn_mode &= ~ISPCCDC_SYN_MODE_INPMOD_MASK;
>> >>       if (format->code == V4L2_MBUS_FMT_YUYV8_2X8 ||
>> >>
>> >> -         format->code == V4L2_MBUS_FMT_UYVY8_2X8)
>> >> -             syn_mode |= ISPCCDC_SYN_MODE_INPMOD_YCBCR8;
>> >> +         format->code == V4L2_MBUS_FMT_UYVY8_2X8){
>> >> +             if (pdata && pdata->bt656)
>> >> +                     syn_mode |= ISPCCDC_SYN_MODE_INPMOD_YCBCR8;
>> >> +             else
>> >> +                     syn_mode |= ISPCCDC_SYN_MODE_INPMOD_YCBCR16;
>> >> +     }
>> >>
>> >>       else if (format->code == V4L2_MBUS_FMT_YUYV8_1X16 ||
>> >>
>> >>                format->code == V4L2_MBUS_FMT_UYVY8_1X16)
>> >>
>> >>               syn_mode |= ISPCCDC_SYN_MODE_INPMOD_YCBCR16;
>> >>
>> >> @@ -1172,7 +1176,8 @@ static void ccdc_configure(struct isp_ccdc_device
>> >> *ccdc) syn_mode &= ~ISPCCDC_SYN_MODE_SDR2RSZ;
>> >>
>> >>       /* Use PACK8 mode for 1byte per pixel formats. */
>> >>
>> >> -     if (omap3isp_video_format_info(format->code)->width <= 8)
>> >> +     if ((omap3isp_video_format_info(format->code)->width <= 8) &&
>> >> +                     (omap3isp_video_format_info(format->code)->bpp <=
>> >> 8))
>> >
>> > I'm not sure to follow you. This will clear the PACK8 bit for the
>> > YUYV8_2X8 formats. Those formats are 8 bits wide, shouldn't PACK8 be set
>> > to store samples on 8 bits instead of 16 bits ?
>> >
>> > Is this patch intended to support YUYV8_2X8 sensors in non BT.656 mode
>> > with the bridge enabled ? In that case, what would you think about setting
>> > the CCDC input format to YUYV8_1X16 instead ? This would better reflect
>> > the reality, as the bridge converts YUYV8_2X8 to YUYV8_1X16, and the CCDC
>> > is then fed with YUYV8_1X16.
>>
>> Yes this is intended for  YUYV8_2X8 sensors in non BT.656 with 8 to 16 bit
>> bridge enabled. So the data has to be stored as 16 bits per sample. Thats
>> why PACK8 is cleared . I am not sure about using YUYV8_1X16.
>
> My original idea when I wrote the YV support patches was to implement this use
> case with YUYV8_2X8 at the sensor output and YUYV8_1X16 at the CCDC input. The
> ISP driver could then enable the bridge automatically. I'm not sure if that's
> the best solution though, it might be confusing for the users. What I would
> like to keep, however, is the idea of enabling the bridge automatically.
>
[Deepthy Ravi] But for streaming to start, the formats on both ends of the link should match. I believe setting different formats at sensor output and ccdc input will give a broken pipe error. Is my understanding correct ? If so, how do you propose to handle the situation ? 

> Sakari, any opinion on this ?
>
>> >>               syn_mode |= ISPCCDC_SYN_MODE_PACK8;
>> >>       else
>> >>               syn_mode &= ~ISPCCDC_SYN_MODE_PACK8;
>
> --
> Regards,
>
> Laurent Pinchart
>

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