> On 24 Feb 2025, at 4:11 PM, andriy.shevchenko@xxxxxxxxxxxxxxx wrote: > > 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. Still the argument here is __le32. %p4h is showing reverse values than what %4pE as well as %.4s shows. > >>>>>> [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 > >
