Re: s5p-fimc VIDIOC_STREAMOFF bug

Re: s5p-fimc VIDIOC_STREAMOFF bug

[Sylwester Nawrocki]

Hi Tomasz,

On 04/19/2012 11:45 PM, Tomasz Figa wrote:
> Hi,
> 
> I have been working on adapting s5p-fimc driver for s3c6410 and everything 
> seems to be working just fine after some minor changes (except minor loss 
> of functionality - only codec path is supported, but for most use cases it 
> does not matter).
> 
> However I think that I have spotted a bug in capture stop / capture suspend 
> handling. In fimc_capture_state_cleanup() the ST_CAPT_SUSPENDED status bit 
> of fimc->state field is being set regardless of suspend parameter, which 
> confuses the driver that FIMC is suspended and might not accept buffers 
> into active queue and so the driver will never start the capture process 
> unless the device gets closed and reopened (because of the condition 
> checking the count of active buffers).
> 
> In my fork for s3c6410 I have moved the set_bit call into 
> fimc_capture_suspend(), so the bit gets set only when the device gets 
> suspended. This seems to solve the problem and I do not see any issues that 
> this could introduce, so it might be a good solution.
> 
> Let me know if I am wrong in anything I have written.

Your conclusions are correct, there was indeed a bug like that.
There is already a patch fixing this [1], but it is going to be available
just from v3.4. I'm considering sending it to Greg for inclusion in the
stable releases, after it gets upstream.

Once I did some preliminary work for the s3c-fimc driver, but dropped this
due to lack of time. If you ever decide you want to mainline your work,
just send the patches to linux-media@vger.kernel.org (and perhaps also to
samsung-soc and ARM Linux) for review.

> 
> Best regards,
> Tomasz Figa

[1] http://patchwork.linuxtv.org/patch/10417


Thanks,
-- 
Sylwester Nawrocki
Samsung Poland R&D Center

Re: s5p-fimc VIDIOC_STREAMOFF bug

[Tomasz Figa]

Hi Sylwester,

Thanks for your response.

On Friday 20 of April 2012 20:24:38 Sylwester Nawrocki wrote:
> Hi Tomasz,
> 
> On 04/19/2012 11:45 PM, Tomasz Figa wrote:
> > Hi,
> > 
> > I have been working on adapting s5p-fimc driver for s3c6410 and
> > everything seems to be working just fine after some minor changes
> > (except minor loss of functionality - only codec path is supported,
> > but for most use cases it does not matter).
> > 
> > However I think that I have spotted a bug in capture stop / capture
> > suspend handling. In fimc_capture_state_cleanup() the
> > ST_CAPT_SUSPENDED status bit of fimc->state field is being set
> > regardless of suspend parameter, which confuses the driver that FIMC
> > is suspended and might not accept buffers into active queue and so
> > the driver will never start the capture process unless the device
> > gets closed and reopened (because of the condition checking the
> > count of active buffers).
> > 
> > In my fork for s3c6410 I have moved the set_bit call into
> > fimc_capture_suspend(), so the bit gets set only when the device gets
> > suspended. This seems to solve the problem and I do not see any
> > issues that this could introduce, so it might be a good solution.
> > 
> > Let me know if I am wrong in anything I have written.
> 
> Your conclusions are correct, there was indeed a bug like that.
> There is already a patch fixing this [1], but it is going to be available
> just from v3.4. I'm considering sending it to Greg for inclusion in the
> stable releases, after it gets upstream.

OK, I must have missed the patch. Good that it has been already noticed and 
fixed.

> Once I did some preliminary work for the s3c-fimc driver, but dropped
> this due to lack of time. If you ever decide you want to mainline your
> work, just send the patches to linux-media@vger.kernel.org (and perhaps
> also to samsung-soc and ARM Linux) for review.

I am not sure sure if there is any interest for more advanced support of 
S3C6410 going into mainline, but if such shows up I am ready to cooperate.

> 
> > Best regards,
> > Tomasz Figa
> 
> [1] http://patchwork.linuxtv.org/patch/10417
> 
> 
> Thanks,