Re: [PATCH v2 1/1] lib/vsprintf: Add support for printing V4L2 and DRM fourccs

From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To: Sakari Ailus <sakari.ailus@linux.intel.com>
Cc: Petr Mladek <pmladek@suse.com>,
	Dave Stevenson <dave.stevenson@raspberrypi.com>,
	Mauro Carvalho Chehab <mchehab+huawei@kernel.org>,
	Rasmus Villemoes <linux@rasmusvillemoes.dk>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	dri-devel <dri-devel@lists.freedesktop.org>,
	Hans Verkuil <hverkuil@xs4all.nl>,
	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
	Andy Shevchenko <andy.shevchenko@gmail.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Joe Perches <joe@perches.com>,
	Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
	Linux Media Mailing List <linux-media@vger.kernel.org>
Subject: Re: [PATCH v2 1/1] lib/vsprintf: Add support for printing V4L2 and DRM fourccs
Date: Sat, 4 Apr 2020 03:21:47 +0300	[thread overview]
Message-ID: <20200404002147.GG9690@pendragon.ideasonboard.com> (raw)
In-Reply-To: <20200404001425.GC4394@kekkonen.localdomain>

Hi Sakari,

On Sat, Apr 04, 2020 at 03:14:25AM +0300, Sakari Ailus wrote:
> On Fri, Apr 03, 2020 at 09:32:42PM +0300, Andy Shevchenko wrote:
> > On Fri, Apr 3, 2020 at 8:54 PM Joe Perches <joe@perches.com> wrote:
> > > On Fri, 2020-04-03 at 19:32 +0200, Mauro Carvalho Chehab wrote:
> > > > Em Fri, 03 Apr 2020 09:56:42 -0700
> > > > Joe Perches <joe@perches.com> escreveu:
> > 
> > > It _might_ be useful to use a CONFIG_MEDIA_SUPPORT guard
> > > in lib/vsprintf for this.
> > 
> > No need. FourCC, if Sakari makes it more generic, can be used for
> > other purposes, e.g. printing component names from the chips (not
> > related to media at all).
> 
> Could you elaborate?
> 
> This could be already used on DRM, presumably, and that does not depend on
> CONFIG_MEDIA_SUPPORT. I don't know how much there would be a need for that,
> though, but this remains a possibility.

/**
 * drm_get_format_name - fill a string with a drm fourcc format's name
 * @format: format to compute name of
 * @buf: caller-supplied buffer
 */
const char *drm_get_format_name(uint32_t format, struct drm_format_name_buf *buf)
{
	snprintf(buf->str, sizeof(buf->str),
		 "%c%c%c%c %s-endian (0x%08x)",
		 printable_char(format & 0xff),
		 printable_char((format >> 8) & 0xff),
		 printable_char((format >> 16) & 0xff),
		 printable_char((format >> 24) & 0x7f),
		 format & DRM_FORMAT_BIG_ENDIAN ? "big" : "little",
		 format);

	return buf->str;
}
EXPORT_SYMBOL(drm_get_format_name);

I'm not advocating for one approach or the other in this case, but we
should standardize 4CC printing between the two subsystems.

-- 
Regards,

Laurent Pinchart
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