Re: [PATCH V10 2/2] media: i2c: ov02a10: Add OV02A10 image sensor driver

From: Dongchun Zhu <dongchun.zhu@mediatek.com>
To: Tomasz Figa <tfiga@chromium.org>
Cc: mark.rutland@arm.com, drinkcat@chromium.org,
	andriy.shevchenko@linux.intel.com, srv_heupstream@mediatek.com,
	devicetree@vger.kernel.org, linus.walleij@linaro.org,
	shengnan.wang@mediatek.com, louis.kuo@mediatek.com,
	bgolaszewski@baylibre.com, sj.huang@mediatek.com,
	robh+dt@kernel.org, linux-mediatek@lists.infradead.org,
	dongchun.zhu@mediatek.com, sakari.ailus@linux.intel.com,
	matthias.bgg@gmail.com, bingbu.cao@intel.com, mchehab@kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-media@vger.kernel.org
Subject: Re: [PATCH V10 2/2] media: i2c: ov02a10: Add OV02A10 image sensor driver
Date: Mon, 29 Jun 2020 14:30:18 +0800	[thread overview]
Message-ID: <1593412218.17166.3.camel@mhfsdcap03> (raw)
In-Reply-To: <20200622152350.GB260716@chromium.org>

Hi Tomasz,

Thanks for the review.

On Mon, 2020-06-22 at 15:23 +0000, Tomasz Figa wrote:
> On Sat, Jun 20, 2020 at 03:48:04PM +0800, Dongchun Zhu wrote:
> > Hi Tomasz,
> > 
> > Thanks for the review.
> > 
> > On Thu, 2020-06-18 at 19:10 +0000, Tomasz Figa wrote:
> > > Hi Dongchun,
> > > 
> > > On Mon, Jun 15, 2020 at 08:29:37PM +0800, Dongchun Zhu wrote:
> > > > Add a V4L2 sub-device driver for OV02A10 image sensor.
> > > > 
> > > > Signed-off-by: Dongchun Zhu <dongchun.zhu@mediatek.com>
> > > > ---
> > > >  MAINTAINERS                 |    1 +
> > > >  drivers/media/i2c/Kconfig   |   13 +
> > > >  drivers/media/i2c/Makefile  |    1 +
> > > >  drivers/media/i2c/ov02a10.c | 1042 +++++++++++++++++++++++++++++++++++++++++++
> > > >  4 files changed, 1057 insertions(+)
> > > >  create mode 100644 drivers/media/i2c/ov02a10.c
> > > > 
> > > 
> > > Thank you for the patch. Please see my comments inline.
> > > 
> > > [snip]
> > > > +static int ov02a10_set_fmt(struct v4l2_subdev *sd,
> > > > +			   struct v4l2_subdev_pad_config *cfg,
> > > > +			   struct v4l2_subdev_format *fmt)
> > > > +{
> > > > +	struct ov02a10 *ov02a10 = to_ov02a10(sd);
> > > > +	struct v4l2_mbus_framefmt *mbus_fmt = &fmt->format;
> > > > +
> > > > +	mutex_lock(&ov02a10->mutex);
> > > > +
> > > > +	if (ov02a10->streaming) {
> > > > +		mutex_unlock(&ov02a10->mutex);
> > > > +		return -EBUSY;
> > > > +	}
> > > > +
> > > > +	/* Only one sensor mode supported */
> > > > +	mbus_fmt->code = ov02a10->fmt.code;
> > > > +	ov02a10_fill_fmt(ov02a10->cur_mode, mbus_fmt);
> > > > +	ov02a10->fmt = fmt->format;
> > > > +
> > > > +	if (fmt->which == V4L2_SUBDEV_FORMAT_TRY)
> > > > +		*v4l2_subdev_get_try_format(sd, cfg, fmt->pad) = fmt->format;
> > > 
> > > If fmt->which is V4L2_SUBDEV_FORMAT_TRY, the internal driver state must not
> > > be affected. It also should not depend on whether the sensor is streaming
> > > or not. Basically it should be considered a special "candidate" format,
> > > which isn't programmed to the hardware, but just stored aside.
> > > 
> > 
> > Hmm. Maybe we shall use FORMAT_TRY like this:
> > struct v4l2_mbus_framefmt *frame_fmt;
> > ...
> > if (fmt->which == V4L2_SUBDEV_FORMAT_TRY)
> > 	frame_fmt = v4l2_subdev_get_try_format(sd, cfg, 0);
> > else
> > 	frame_fmt = &ov02a10->fmt;
> > 
> > *frame_fmt = *mbus_fmt;
> > 
> > (Remove 'ov02a10->fmt = fmt->format;' above)
> >
> 
> Yes, I guess that should work. Also the ov02a10->streaming condition
> shouldn't be checked if fmt->which is V4L2_SUBDEV_FORMAT_TRY).
> 

Maybe we shall use more strict condition to check streaming state:
'if (ov02a10->streaming)' --> 'if (ov02a10->streaming && fmt->which ==
V4L2_SUBDEV_FORMAT_ACTIVE)'

> Best regards,
> Tomasz

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