| Message ID | C66F35BB-2ECC-4DB8-8154-DEC5177967ED@live.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [v2,1/3] drm/format-helper: Add conversion from XRGB8888 to BGR888 | expand |
On Thu, Feb 20 2025, Aditya Garg <gargaditya08@live.com> wrote: > v2 -> Add this patch > Documentation/core-api/printk-formats.rst | 32 +++++++++++++++++++ > lib/test_printf.c | 39 +++++++++++++++++++---- > lib/vsprintf.c | 38 ++++++++++++++++++---- Yay! Thanks for remembering to include test cases. > > diff --git a/lib/test_printf.c b/lib/test_printf.c > index 59dbe4f9a..ee860327e 100644 > --- a/lib/test_printf.c > +++ b/lib/test_printf.c > @@ -776,21 +776,46 @@ static void __init fwnode_pointer(void) > software_node_unregister_node_group(group); > } > > +struct fourcc_struct { > + u32 code; > + const char *str; > +}; > + > +static void __init fourcc_pointer_test(const struct fourcc_struct *fc, size_t n, > + const char *fmt) > +{ > + size_t i; > + > + for (i = 0; i < n; i++) > + test(fc[i].str, fmt, &fc[i].code); > +} > + > static void __init fourcc_pointer(void) > { > - struct { > - u32 code; > - char *str; > - } const try[] = { > + struct fourcc_struct const try_cc[] = { I know it matches the code it replaces, but kernel style seems to be "const struct foo" rather than "struct foo const" (at around 130:1) - just as you use in the new helper function. Also, please consider changing the array, and the newly added instances, to be static instead of automatic (our le32_to_cpu should be usable also for static initializers). This will conflict with the conversion-to-kunit which is in flight, but the conflict should be trivial to resolve. Rasmus
Hi > >> >> diff --git a/lib/test_printf.c b/lib/test_printf.c >> index 59dbe4f9a..ee860327e 100644 >> --- a/lib/test_printf.c >> +++ b/lib/test_printf.c >> @@ -776,21 +776,46 @@ static void __init fwnode_pointer(void) >> software_node_unregister_node_group(group); >> } >> >> +struct fourcc_struct { >> + u32 code; >> + const char *str; >> +}; >> + >> +static void __init fourcc_pointer_test(const struct fourcc_struct *fc, size_t n, >> + const char *fmt) >> +{ >> + size_t i; >> + >> + for (i = 0; i < n; i++) >> + test(fc[i].str, fmt, &fc[i].code); >> +} >> + >> static void __init fourcc_pointer(void) >> { >> - struct { >> - u32 code; >> - char *str; >> - } const try[] = { >> + struct fourcc_struct const try_cc[] = { > > I know it matches the code it replaces, but kernel style seems to be > "const struct foo" rather than "struct foo const" (at around 130:1) - > just as you use in the new helper function. > > Also, please consider changing the array, and the newly added instances, > to be static instead of automatic (our le32_to_cpu should be usable also > for static initializers). > V3 sent here: https://lore.kernel.org/dri-devel/98289BC4-D5E1-41B8-AC89-632DBD2C2789@live.com/T/#mfa1dac647c9517674649a50301b122a524cc364c
On Thu, Feb 20, 2025 at 04:39:23PM +0000, Aditya Garg wrote: > From: Hector Martin <marcan@marcan.st> > > %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). ... > orig = get_unaligned(fourcc); > - val = orig & ~BIT(31); > + switch (fmt[2]) { > + case 'h': > + val = orig; > + break; > + case 'r': > + orig = swab32(orig); > + val = orig; > + break; > + case 'l': > + orig = le32_to_cpu(orig); > + val = orig; > + break; > + case 'b': > + orig = be32_to_cpu(orig); I do not see that orig is a union of different types. Have you run sparse? It will definitely complain on this code. > + val = orig; > + break; > + case 'c': > + /* Pixel formats are printed LSB-first */ > + val = swab32(orig & ~BIT(31)); > + pixel_fmt = true; > + break; > + default: > + return error_string(buf, end, "(%p4?)", spec); > + } ... > - *p++ = ' '; > - strcpy(p, orig & BIT(31) ? "big-endian" : "little-endian"); > - p += strlen(p); > + if (pixel_fmt) { Technically we can avoid a boolean by checking fmt[2] again here, but I'm okay with a temporary holder. > + *p++ = ' '; > + strcpy(p, orig & BIT(31) ? "big-endian" : "little-endian"); > + p += strlen(p); > + }
> On 21 Feb 2025, at 8:57 PM, andriy.shevchenko@linux.intel.com wrote: > > On Thu, Feb 20, 2025 at 04:39:23PM +0000, Aditya Garg wrote: >> From: Hector Martin <marcan@marcan.st> >> >> %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). > > ... > >> orig = get_unaligned(fourcc); >> - val = orig & ~BIT(31); >> + switch (fmt[2]) { >> + case 'h': >> + val = orig; >> + break; >> + case 'r': >> + orig = swab32(orig); >> + val = orig; >> + break; >> + case 'l': > >> + orig = le32_to_cpu(orig); >> + val = orig; >> + break; >> + case 'b': >> + orig = be32_to_cpu(orig); > > I do not see that orig is a union of different types. Have you run sparse? > It will definitely complain on this code. Does this look good now? Made orig a union. char *fourcc_string(char *buf, char *end, const u32 *fourcc, const char *fmt, struct printf_spec spec) { char output[sizeof("0123 little-endian (0x01234567)")]; char *p = output; unsigned int i; bool pixel_fmt = false; u32 val; union { u32 raw; __le32 le; __be32 be; } orig; if (fmt[1] != 'c') return error_string(buf, end, "(%p4?)", spec); if (check_pointer(&buf, end, fourcc, spec)) return buf; orig.raw = get_unaligned(fourcc); switch (fmt[2]) { case 'h': val = orig.raw; break; case 'r': val = swab32(orig.raw); break; case 'l': val = le32_to_cpu(orig.le); break; case 'b': val = be32_to_cpu(orig.be); break; case 'c': val = swab32(orig.raw & ~BIT(31)); pixel_fmt = true; break; default: return error_string(buf, end, "(%p4?)", spec); } for (i = 0; i < sizeof(u32); i++) { unsigned char c = val >> ((3 - i) * 8); *p++ = isascii(c) && isprint(c) ? c : '.'; } if (pixel_fmt) { *p++ = ' '; strcpy(p, orig.raw & BIT(31) ? "big-endian" : "little-endian"); p += strlen(p); } *p++ = ' '; *p++ = '('; p += sprintf(p, "0x%08x", orig.raw); *p++ = ')'; *p = '\0'; return string_nocheck(buf, end, output, spec); }
> Does this look good now? Made orig a union. Wait, it's messier. Maybe declare data type of val separately in each case? > > char *fourcc_string(char *buf, char *end, const u32 *fourcc, const char *fmt, struct printf_spec spec) > { > char output[sizeof("0123 little-endian (0x01234567)")]; > char *p = output; > unsigned int i; > bool pixel_fmt = false; > u32 val; > > union { > u32 raw; > __le32 le; > __be32 be; > } orig; > > if (fmt[1] != 'c') > return error_string(buf, end, "(%p4?)", spec); > > if (check_pointer(&buf, end, fourcc, spec)) > return buf; > > orig.raw = get_unaligned(fourcc); > > switch (fmt[2]) { > case 'h': > val = orig.raw; > break; > case 'r': > val = swab32(orig.raw); > break; > case 'l': > val = le32_to_cpu(orig.le); > break; > case 'b': > val = be32_to_cpu(orig.be); > break; > case 'c': > val = swab32(orig.raw & ~BIT(31)); > pixel_fmt = true; > break; > default: > return error_string(buf, end, "(%p4?)", spec); > } > > for (i = 0; i < sizeof(u32); i++) { > unsigned char c = val >> ((3 - i) * 8); > *p++ = isascii(c) && isprint(c) ? c : '.'; > } > > if (pixel_fmt) { > *p++ = ' '; > strcpy(p, orig.raw & BIT(31) ? "big-endian" : "little-endian"); > p += strlen(p); > } > > *p++ = ' '; > *p++ = '('; > p += sprintf(p, "0x%08x", orig.raw); > *p++ = ')'; > *p = '\0'; > > return string_nocheck(buf, end, output, spec); > } >
On Fri, Feb 21, 2025 at 08:06:51PM +0000, Aditya Garg wrote: > > > Does this look good now? Made orig a union. > > Wait, it's messier. Maybe declare data type of val separately in each case? Yes, this sounds better.
> On 21 Feb 2025, at 8:57 PM, andriy.shevchenko@linux.intel.com wrote: > > On Thu, Feb 20, 2025 at 04:39:23PM +0000, Aditya Garg wrote: >> From: Hector Martin <marcan@marcan.st> >> >> %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). > > ... > >> orig = get_unaligned(fourcc); >> - val = orig & ~BIT(31); >> + switch (fmt[2]) { >> + case 'h': >> + val = orig; >> + break; >> + case 'r': >> + orig = swab32(orig); >> + val = orig; >> + break; >> + case 'l': > >> + orig = le32_to_cpu(orig); >> + val = orig; >> + break; >> + case 'b': >> + orig = be32_to_cpu(orig); > > I do not see that orig is a union of different types. Have you run sparse? > It will definitely complain on this code. After messing around with this, what I’ve noticed is that orig and val used in this struct should be u32. Now in case of little endian and big endian, that things are messy. The original code by Hector was using le32_to_cpu on orig, which itself is declared as a u32 here (maybe was done with the intention to convert le32 orig to u32 orig?). Anyways, what I have done is that: 1. Declare new variable, orig_le which is __le32. 2. Instead of doing orig = le32_to_cpu(orig); , we can do orig_le = cpu_to_le32(orig). This fixes the sparse warning: cast to restricted __le32 3. Now the original code was intending to use val=orig=le32_to_cpu(orig) at the bottom part of this struct. Those parts also require val and orig to be u32. For that, we are now using le32_to_cpu(orig_le). Since val is same as orig, in case these cases, instead of making a val_le, I’ve simply used orig_le there as well. Similar changes done for big endian. So, the struct looks like this now: static noinline_for_stack char *fourcc_string(char *buf, char *end, const u32 *fourcc, struct printf_spec spec, const char *fmt) { char output[sizeof("0123 little-endian (0x01234567)")]; char *p = output; unsigned int i; unsigned char c; bool pixel_fmt = false; u32 orig, val; __le32 orig_le; __be32 orig_be; if (fmt[1] != 'c') return error_string(buf, end, "(%p4?)", spec); if (check_pointer(&buf, end, fourcc, spec)) return buf; orig = get_unaligned(fourcc); switch (fmt[2]) { case 'h': val = orig; break; case 'r': orig = swab32(orig); val = orig; break; case 'l': orig_le = cpu_to_le32(orig); break; case 'b': orig_be = cpu_to_be32(orig); break; case 'c': /* Pixel formats are printed LSB-first */ val = swab32(orig & ~BIT(31)); pixel_fmt = true; break; default: return error_string(buf, end, "(%p4?)", spec); } for (i = 0; i < sizeof(u32); i++) { switch (fmt[2]) { case 'h': case 'r': case 'c': c = val >> ((3 - i) * 8); break; case 'l': c = le32_to_cpu(orig_le) >> ((3 - i) * 8); break; case 'b': c = be32_to_cpu(orig_be) >> ((3 - i) * 8); break; } /* Print non-control ASCII characters as-is, dot otherwise */ *p++ = isascii(c) && isprint(c) ? c : '.'; } if (pixel_fmt) { *p++ = ' '; strcpy(p, orig & BIT(31) ? "big-endian" : "little-endian"); p += strlen(p); } *p++ = ' '; *p++ = '('; switch (fmt[2]) { case 'h': case 'r': case 'c': p = special_hex_number(p, output + sizeof(output) - 2, orig, sizeof(u32)); break; case 'l': p = special_hex_number(p, output + sizeof(output) - 2, le32_to_cpu(orig_le), sizeof(u32)); break; case 'b': p = special_hex_number(p, output + sizeof(output) - 2, be32_to_cpu(orig_be), sizeof(u32)); break; } *p++ = ')'; *p = '\0'; return string(buf, end, output, spec); } Andy, could you verify this?
> On 20 Feb 2025, at 10:09 PM, Aditya Garg <gargaditya08@live.com> wrote: > > From: Hector Martin <marcan@marcan.st> > > %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). > > Signed-off-by: Hector Martin <marcan@marcan.st> > Signed-off-by: Aditya Garg <gargaditya08@live.com> 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 [1]: https://lore.kernel.org/asahi/E753B391-D2CB-4213-AF82-678ADD5A7644@cutebit.org/ 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. > > > --- > - *p++ = ' '; > - strcpy(p, orig & BIT(31) ? "big-endian" : "little-endian"); > - p += strlen(p); > + if (pixel_fmt) { > + *p++ = ' '; > + strcpy(p, orig & BIT(31) ? "big-endian" : "little-endian"); > + p += strlen(p); > + }
diff --git a/Documentation/core-api/printk-formats.rst b/Documentation/core-api/printk-formats.rst index ecccc0473..9982861fa 100644 --- a/Documentation/core-api/printk-formats.rst +++ b/Documentation/core-api/printk-formats.rst @@ -648,6 +648,38 @@ Examples:: %p4cc Y10 little-endian (0x20303159) %p4cc NV12 big-endian (0xb231564e) +Generic FourCC code +------------------- + +:: + %p4c[hrbl] gP00 (0x67503030) + +Print a generic FourCC code, as both ASCII characters and its numerical +value as hexadecimal. + +The additional ``h``, ``r``, ``b``, and ``l`` specifiers are used to specify +host, reversed, big or little endian order data respectively. Host endian +order means the data is interpreted as a 32-bit integer and the most +significant byte is printed first; that is, the character code as printed +matches the byte order stored in memory on big-endian systems, and is reversed +on little-endian systems. + +Passed by reference. + +Examples for a little-endian machine, given &(u32)0x67503030:: + + %p4ch gP00 (0x67503030) + %p4cr 00Pg (0x30305067) + %p4cb 00Pg (0x30305067) + %p4cl gP00 (0x67503030) + +Examples for a big-endian machine, given &(u32)0x67503030:: + + %p4ch gP00 (0x67503030) + %p4cr 00Pg (0x30305067) + %p4cb gP00 (0x67503030) + %p4cl 00Pg (0x30305067) + Rust ---- diff --git a/lib/test_printf.c b/lib/test_printf.c index 59dbe4f9a..ee860327e 100644 --- a/lib/test_printf.c +++ b/lib/test_printf.c @@ -776,21 +776,46 @@ static void __init fwnode_pointer(void) software_node_unregister_node_group(group); } +struct fourcc_struct { + u32 code; + const char *str; +}; + +static void __init fourcc_pointer_test(const struct fourcc_struct *fc, size_t n, + const char *fmt) +{ + size_t i; + + for (i = 0; i < n; i++) + test(fc[i].str, fmt, &fc[i].code); +} + static void __init fourcc_pointer(void) { - struct { - u32 code; - char *str; - } const try[] = { + struct fourcc_struct const try_cc[] = { { 0x3231564e, "NV12 little-endian (0x3231564e)", }, { 0xb231564e, "NV12 big-endian (0xb231564e)", }, { 0x10111213, ".... little-endian (0x10111213)", }, { 0x20303159, "Y10 little-endian (0x20303159)", }, }; - unsigned int i; + struct fourcc_struct const try_ch = { + 0x41424344, "ABCD (0x41424344)", + }; + struct fourcc_struct const try_cr = { + 0x41424344, "DCBA (0x44434241)", + }; + struct fourcc_struct const try_cl = { + le32_to_cpu(0x41424344), "ABCD (0x41424344)", + }; + struct fourcc_struct const try_cb = { + be32_to_cpu(0x41424344), "ABCD (0x41424344)", + }; - for (i = 0; i < ARRAY_SIZE(try); i++) - test(try[i].str, "%p4cc", &try[i].code); + fourcc_pointer_test(try_cc, ARRAY_SIZE(try_cc), "%p4cc"); + fourcc_pointer_test(&try_ch, 1, "%p4ch"); + fourcc_pointer_test(&try_cr, 1, "%p4cr"); + fourcc_pointer_test(&try_cl, 1, "%p4cl"); + fourcc_pointer_test(&try_cb, 1, "%p4cb"); } static void __init diff --git a/lib/vsprintf.c b/lib/vsprintf.c index 56fe96319..13733a4da 100644 --- a/lib/vsprintf.c +++ b/lib/vsprintf.c @@ -1781,27 +1781,53 @@ char *fourcc_string(char *buf, char *end, const u32 *fourcc, char output[sizeof("0123 little-endian (0x01234567)")]; char *p = output; unsigned int i; + bool pixel_fmt = false; u32 orig, val; - if (fmt[1] != 'c' || fmt[2] != 'c') + if (fmt[1] != 'c') return error_string(buf, end, "(%p4?)", spec); if (check_pointer(&buf, end, fourcc, spec)) return buf; orig = get_unaligned(fourcc); - val = orig & ~BIT(31); + switch (fmt[2]) { + case 'h': + val = orig; + break; + case 'r': + orig = swab32(orig); + val = orig; + break; + case 'l': + orig = le32_to_cpu(orig); + val = orig; + break; + case 'b': + orig = be32_to_cpu(orig); + val = orig; + break; + case 'c': + /* Pixel formats are printed LSB-first */ + val = swab32(orig & ~BIT(31)); + pixel_fmt = true; + break; + default: + return error_string(buf, end, "(%p4?)", spec); + } for (i = 0; i < sizeof(u32); i++) { - unsigned char c = val >> (i * 8); + unsigned char c = val >> ((3 - i) * 8); /* Print non-control ASCII characters as-is, dot otherwise */ *p++ = isascii(c) && isprint(c) ? c : '.'; } - *p++ = ' '; - strcpy(p, orig & BIT(31) ? "big-endian" : "little-endian"); - p += strlen(p); + if (pixel_fmt) { + *p++ = ' '; + strcpy(p, orig & BIT(31) ? "big-endian" : "little-endian"); + p += strlen(p); + } *p++ = ' '; *p++ = '('; diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl index 7b28ad331..21516f753 100755 --- a/scripts/checkpatch.pl +++ b/scripts/checkpatch.pl @@ -6904,7 +6904,7 @@ sub process { ($extension eq "f" && defined $qualifier && $qualifier !~ /^w/) || ($extension eq "4" && - defined $qualifier && $qualifier !~ /^cc/)) { + defined $qualifier && $qualifier !~ /^c[chlbr]/)) { $bad_specifier = $specifier; last; }