> 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. > >>>> [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 > >
