On Mon, Feb 24, 2025 at 10:32:27AM +0000, Aditya Garg wrote: > > On 24 Feb 2025, at 3:54 PM, andriy.shevchenko@xxxxxxxxxxxxxxx wrote: > > 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. > > %.4s is used for unsigned int iirc, here it's __le32. No, it's used to 'char *'. in case one may guarantee that it at least is four characters long. > >>>> [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
