On Thu, Dec 10, 2020 at 03:55:27PM +0200, Sakari Ailus wrote: > On Thu, Dec 10, 2020 at 03:05:02PM +0200, Andy Shevchenko wrote: > > On Thu, Dec 10, 2020 at 2:16 PM Petr Mladek <pmladek@xxxxxxxx> wrote: > > > On Fri 2020-11-13 12:54:41, Sakari Ailus wrote: > > > > Add a printk modifier %p4cc (for pixel format) for printing V4L2 and DRM > > > > pixel formats denoted by fourccs. The fourcc encoding is the same for both > > > > so the same implementation can be used. > > > > > > > > Suggested-by: Mauro Carvalho Chehab <mchehab@xxxxxxxxxx> > > > > Signed-off-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx> > > > > > > Andy, Rasmus, > > > > > > the last version looks fine to me. I am going to push it. > > > Please, speak up if you are against it. > > > > My concerns are: > > - not so standard format of representation (why not to use > > string_escape_mem() helper?) or is it? > > The format string may contain spaces that are not meant to be printed. > Other unprintable chacaters should not be present (at least not in V4L2 > pixelformats). The hexadecimal representation is there to convey the > numerical value and that originally came from DRM, not V4L2. Yes, but I mean that we usually anticipate the escaped characters in a form of '\xNN' (hex) or '\NNN' (octal). The format '(NN)' is quite unusual to me. > > - no compatibility with generic 4cc > > (I would rather have an additional specifier here for v4l2 cases. > > What do you mean by "generic 4cc"? There are two users of 4cc codes in the > kernel that I know of: V4L2 and DRM. Something that does not refer to > in-memory pixel formats? Of course. Everything else. 4cc is a generic term to describe something which is of 4 characters long [1]. It's not limited by media file formats. And moreover some (chip) vendors are using it as well (Synopsys). Microsoft uses 4cc in CSRT ACPI table for vendor field and so on... [1]: https://en.wikipedia.org/wiki/FourCC -- With Best Regards, Andy Shevchenko _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
