linux-kernel - Re: [PATCH] media: i2c: tvp514x: add support for asynchronous probing

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Message-ID: <CA+V-a8vaOPcxxEqoXtia1O=bCpyWAWOrc_xj80O+LmmeLXigEw@mail.gmail.com>
Date:	Mon, 24 Jun 2013 14:23:37 +0530
From:	Prabhakar Lad <prabhakar.csengg@...il.com>
To:	Hans Verkuil <hverkuil@...all.nl>
Cc:	Guennadi Liakhovetski <g.liakhovetski@....de>,
	Mauro Carvalho Chehab <mchehab@...hat.com>,
	LMML <linux-media@...r.kernel.org>,
	Hans Verkuil <hans.verkuil@...co.com>,
	Laurent Pinchart <laurent.pinchart@...asonboard.com>,
	DLOS <davinci-linux-open-source@...ux.davincidsp.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Sakari Ailus <sakari.ailus@....fi>
Subject: Re: [PATCH] media: i2c: tvp514x: add support for asynchronous probing

Hi Hans,

On Mon, Jun 24, 2013 at 2:09 PM, Hans Verkuil <hverkuil@...all.nl> wrote:
> On Mon June 24 2013 10:24:02 Prabhakar Lad wrote:
>> Hi Hans,
>>
>> On Mon, Jun 24, 2013 at 12:41 PM, Hans Verkuil <hverkuil@...all.nl> wrote:
>> > On Sun June 23 2013 17:48:20 Prabhakar Lad wrote:
>> >> Hi Guennadi,
>> >>
>> >> Thanks for the review.
>> >>
>> >> On Sun, Jun 23, 2013 at 8:49 PM, Guennadi Liakhovetski
>> >> <g.liakhovetski@....de> wrote:
>> >> > On Sat, 22 Jun 2013, Prabhakar Lad wrote:
>> >> >
>> >> >> From: "Lad, Prabhakar" <prabhakar.csengg@...il.com>
>> >> >>
>> >> >> Both synchronous and asynchronous tvp514x subdevice probing is supported by
>> >> >> this patch.
>> >> >>
>> >> >> Signed-off-by: Prabhakar Lad <prabhakar.csengg@...il.com>
>> >> >> Cc: Guennadi Liakhovetski <g.liakhovetski@....de>
>> >> >> Cc: Laurent Pinchart <laurent.pinchart@...asonboard.com>
>> >> >> Cc: Hans Verkuil <hverkuil@...all.nl>
>> >> >> Cc: Sakari Ailus <sakari.ailus@....fi>
>> >> >> Cc: Mauro Carvalho Chehab <mchehab@...hat.com>
>> >> >> ---
>> >> >>  drivers/media/i2c/tvp514x.c |   22 +++++++++++++++-------
>> >> >>  1 file changed, 15 insertions(+), 7 deletions(-)
>> >> >>
>> >> >> diff --git a/drivers/media/i2c/tvp514x.c b/drivers/media/i2c/tvp514x.c
>> >> >> index 864eb14..d090caf 100644
>> >> >> --- a/drivers/media/i2c/tvp514x.c
>> >> >> +++ b/drivers/media/i2c/tvp514x.c
>> >> >> @@ -36,6 +36,7 @@
>> >> >>  #include <linux/module.h>
>> >> >>  #include <linux/v4l2-mediabus.h>
>> >> >>
>> >> >> +#include <media/v4l2-async.h>
>> >> >>  #include <media/v4l2-device.h>
>> >> >>  #include <media/v4l2-common.h>
>> >> >>  #include <media/v4l2-mediabus.h>
>> >> >
>> >> > Ok, but this one really does too many things in one patch:
>> >> >
>> >> >> @@ -1148,9 +1149,9 @@ tvp514x_probe(struct i2c_client *client, const struct i2c_device_id *id)
>> >> >>       /* Register with V4L2 layer as slave device */
>> >> >>       sd = &decoder->sd;
>> >> >>       v4l2_i2c_subdev_init(sd, client, &tvp514x_ops);
>> >> >> -     strlcpy(sd->name, TVP514X_MODULE_NAME, sizeof(sd->name));
>> >> >>
>> >> >>  #if defined(CONFIG_MEDIA_CONTROLLER)
>> >> >> +     strlcpy(sd->name, TVP514X_MODULE_NAME, sizeof(sd->name));
>> >> >
>> >> > This is unrelated
>> >> >
>> >> OK I'll split the patch or may be a line in a commit message can do ?
>> >
>> > Please split it up in two patches.
>> >
>> > Why is sd->name set anyway? And why is it moved under CONFIG_MEDIA_CONTROLLER?
>> > It's not obvious to me.
>> >
>> while using tvp514x subdev with media controller based drivers, when we
>> enumerate entities (MEDIA_IOC_ENUM_ENTITIES) to get the index id
>> of the entity we compare the entity name with "tvp514x", So I moved it
>> under CONFIG_MEDIA_CONTROLLER config. I hope you are OK with
>> moving this in a separate patch.
>
> Sorry, but this approach is wrong. sd->name must be a unique name, so manually
> setting sd->name will fail if you have two tvp514x devices.
>
> There is no reason to override sd->name here, and it is actually a bug. I see
> that tvp7002 has the same problem (and a bunch of others as well).
>
> When trying to find a tvp514x you can just use strstr() in your application.
> That will work all the time as long as there is only one tvp514x.

OK, then I will send out a cleanup patch removing sd->name from this driver
and others too.

Regards,
--Prabhakar Lad
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