On Mon, Feb 24, 2025 at 10:18:48AM +0000, Aditya Garg wrote: > > > > On 24 Feb 2025, at 3:28 PM, andriy.shevchenko@xxxxxxxxxxxxxxx wrote: > > > > On Sat, Feb 22, 2025 at 03:46:03PM +0000, Aditya Garg wrote: > >>>> On 20 Feb 2025, at 10:09 PM, Aditya Garg <gargaditya08@xxxxxxxx> wrote: > >>> > >>> %p4cc is designed for DRM/V4L2 FOURCCs with their specific quirks, but > >>> it's useful to be able to print generic 4-character codes formatted as > >>> an integer. Extend it to add format specifiers for printing generic > >>> 32-bit FOURCCs with various endian semantics: > >>> > >>> %p4ch Host-endian > >>> %p4cl Little-endian > >>> %p4cb Big-endian > >>> %p4cr Reverse-endian > >>> > >>> The endianness determines how bytes are interpreted as a u32, and the > >>> FOURCC is then always printed MSByte-first (this is the opposite of > >>> V4L/DRM FOURCCs). This covers most practical cases, e.g. %p4cr would > >>> allow printing LSByte-first FOURCCs stored in host endian order > >>> (other than the hex form being in character order, not the integer > >>> value). > > > > ... > > > >> BTW, after looking at the comments by Martin [1], its actually better to use > >> existing specifiers for the appletbdrm driver. The driver needs the host > >> endian as proposed by this patch, so instead of that, we can use %.4s > > > > Do you mean this patch will not be needed? If this a case, that would be the > > best solution. > > I tested with %4pE, and the results are different from expected. So this > would be preferred. Kindly see my latest email with a proposed workaround for > the sparse warnings. %.4s sounded okay, but %4pE is always about escaping and the result may occupy %4x memory (octal escaping of non-printable characters). Of course, you may vary the escaping classes, but IIRC the octal or hex escaping is unconditional. > >> [1]: https://lore.kernel.org/asahi/E753B391-D2CB-4213-AF82-678ADD5A7644@xxxxxxxxxxx/ > >> > >> Alternatively we could add a host endian only. Other endians are not really > >> used by any driver AFAIK. The host endian is being used by appletbdrm and > >> Asahi Linux’ SMC driver only. -- With Best Regards, Andy Shevchenko
