linux-kernel - Re: [PATCH 2/2] media: atmel-isi: move configure_geometry() to start

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Date:	Mon, 03 Aug 2015 16:27:12 +0300
From:	Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:	Josh Wu <josh.wu@...el.com>
Cc:	Linux Media Mailing List <linux-media@...r.kernel.org>,
	Guennadi Liakhovetski <g.liakhovetski@....de>,
	Mauro Carvalho Chehab <mchehab@....samsung.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] media: atmel-isi: move configure_geometry() to start_streaming()

Hi Josh,

On Monday 03 August 2015 11:56:01 Josh Wu wrote:
> On 7/31/2015 10:37 PM, Laurent Pinchart wrote:
> > On Wednesday 17 June 2015 18:39:39 Josh Wu wrote:
> >> As in set_fmt() function we only need to know which format is been set,
> >> we don't need to access the ISI hardware in this moment.
> >> 
> >> So move the configure_geometry(), which access the ISI hardware, to
> >> start_streaming() will make code more consistent and simpler.
> >> 
> >> Signed-off-by: Josh Wu <josh.wu@...el.com>
> >> ---
> >> 
> >>   drivers/media/platform/soc_camera/atmel-isi.c | 17 +++++------------
> >>   1 file changed, 5 insertions(+), 12 deletions(-)
> >> 
> >> diff --git a/drivers/media/platform/soc_camera/atmel-isi.c
> >> b/drivers/media/platform/soc_camera/atmel-isi.c index 8bc40ca..b01086d
> >> 100644
> >> --- a/drivers/media/platform/soc_camera/atmel-isi.c
> >> +++ b/drivers/media/platform/soc_camera/atmel-isi.c
> >> @@ -390,6 +390,11 @@ static int start_streaming(struct vb2_queue *vq,
> >> unsigned int count) /* Disable all interrupts */
> >> 
> >>   	isi_writel(isi, ISI_INTDIS, (u32)~0UL);
> >> 
> >> +	ret = configure_geometry(isi, icd->user_width, icd->user_height,
> >> +				icd->current_fmt->code);
> > 
> > I would also make configure_geometry a void function, as the only failure
> > case really can't occur.
> 
> I think this case can be reached if user require a RGB565 format to
> capture and sensor also support RGB565 format.
> As atmel-isi driver will provide RGB565 support via the pass-through
> mode (maybe we need re-consider this part).
> 
> So that will cause the configure_geometry() returns an error since it
> found the bus format is not Y8 or YUV422.
> 
> In my opinion, we should not change configure_geometry()'s return type,
> until we add a insanity format check before we call configure_geometry()
> in future.

It will really confuse the user if S_FMT accepts a format but STREAMON fails 
due to the format being unsupported. Could that be fixed by defaulting to a 
known supported format in S_FMT if the requested format isn't support ? You 
could then remove the error check in configure_geometry().

> > Apart from that,
> > 
> > Reviewed-by: Laurent Pinchart <laurent.pinchart@...asonboard.com>
> 
> Thanks for the review.
> 
> Best Regards,
> Josh Wu
> 
> >> +	if (ret < 0)
> >> +		return ret;
> >> +
> >> 
> >>   	spin_lock_irq(&isi->lock);
> >>   	/* Clear any pending interrupt */
> >>   	isi_readl(isi, ISI_STATUS);
> >> 
> >> @@ -477,8 +482,6 @@ static int isi_camera_init_videobuf(struct vb2_queue
> >> *q, static int isi_camera_set_fmt(struct soc_camera_device *icd,
> >> 
> >>   			      struct v4l2_format *f)
> >>   
> >>   {
> >> 
> >> -	struct soc_camera_host *ici = to_soc_camera_host(icd->parent);
> >> -	struct atmel_isi *isi = ici->priv;
> >> 
> >>   	struct v4l2_subdev *sd = soc_camera_to_subdev(icd);
> >>   	const struct soc_camera_format_xlate *xlate;
> >>   	struct v4l2_pix_format *pix = &f->fmt.pix;
> >> 
> >> @@ -511,16 +514,6 @@ static int isi_camera_set_fmt(struct
> >> soc_camera_device
> >> *icd, if (mf->code != xlate->code)
> >> 
> >>   		return -EINVAL;
> >> 
> >> -	/* Enable PM and peripheral clock before operate isi registers */
> >> -	pm_runtime_get_sync(ici->v4l2_dev.dev);
> >> -
> >> -	ret = configure_geometry(isi, pix->width, pix->height, xlate->code);
> >> -
> >> -	pm_runtime_put(ici->v4l2_dev.dev);
> >> -
> >> -	if (ret < 0)
> >> -		return ret;
> >> -
> >> 
> >>   	pix->width		= mf->width;
> >>   	pix->height		= mf->height;
> >>   	pix->field		= mf->field;

-- 
Regards,

Laurent Pinchart

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