Re: [PATCH v2 1/2] lib/vsprintf: Add support for generic FourCCs by extending %p4cc

[Aditya Garg]

> On 13 Mar 2025, at 4:49 PM, Aditya Garg <gargaditya08@xxxxxxxx> wrote:
> 
> From: Hector Martin <marcan@xxxxxxxxx>
> 
> %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 byte order
> %p4cn Network byte order
> %p4cl Little-endian
> %p4cb Big-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. %p4cn would
> allow printing LSByte-first FourCCs stored in host endian order
> (other than the hex form being in character order, not the integer
> value).
> 
> Acked-by: Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx>
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
> Reviewed-by: Petr Mladek <pmladek@xxxxxxxx>
> Tested-by: Petr Mladek <pmladek@xxxxxxxx>
> Signed-off-by: Hector Martin <marcan@xxxxxxxxx>
> Signed-off-by: Aditya Garg <gargaditya08@xxxxxxxx>
> ---
> Documentation/core-api/printk-formats.rst | 32 +++++++++++++++++++++
> lib/vsprintf.c                            | 35 +++++++++++++++++++----
> scripts/checkpatch.pl                     |  2 +-
> 3 files changed, 62 insertions(+), 7 deletions(-)

FWIW, the test_printf.c part, as suggested by Petr, which was removed in v2, has been sent to Kees here:

https://lore.kernel.org/lkml/4378DDFE-3263-497A-8364-433DC1984FEE@xxxxxxxx/T/#u

The series should be good to merge now.