linux-kernel - Re: [PATCH v3 2/3] lib/vsprintf: Add support for generic FOURCCs by extending %p4cc

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Message-ID: <ED4B4FD3-CD26-4200-97E0-BC01B3408A4C@live.com>
Date: Fri, 21 Feb 2025 19:37:17 +0000
From: Aditya Garg <gargaditya08@...e.com>
To: "andriy.shevchenko@...ux.intel.com" <andriy.shevchenko@...ux.intel.com>
CC: "pmladek@...e.com" <pmladek@...e.com>, Steven Rostedt
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Subject: Re: [PATCH v3 2/3] lib/vsprintf: Add support for generic FOURCCs by
 extending %p4cc



> On 21 Feb 2025, at 8:59 PM, andriy.shevchenko@...ux.intel.com wrote:
> 
> On Fri, Feb 21, 2025 at 11:37:13AM +0000, Aditya Garg wrote:
>> From: Hector Martin <marcan@...can.st>
> 
> First of all, I do not see the cover letter. Is it only an issue on my side?

These are literally 3 patches that are self explanatory. Is this a hard and fast rule that a cover letter MUST be there?

> 
>> %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).
> 
> Second, don't issue versions too fast, give at least a few days for the
> reviewers to have a chance on looking into it.

Sure, I’ll take care of that.

BTW, a found a typo:

+ static const struct fourcc_struct try_ch = {
+ 0x41424344, "ABCD (0x41424344)",
+ };
+ struct const struct fourcc_struct try_cr = {
+ 0x41424344, "DCBA (0x44434241)",
+ };
+ static const struct fourcc_struct try_cl = {
+ le32_to_cpu(0x41424344), "ABCD (0x41424344)",
+ };
+ struct const struct fourcc_struct try_cb = {
+ be32_to_cpu(0x41424344), "ABCD (0x41424344)",
+ };

Mistyped struct instead of static. Will fix in v4.