Add a printk modifier %p4cc (for pixel format) for printing V4L2 and DRM pixel formats denoted by fourccs. The fourcc encoding is the same for both so the same implementation can be used.

Suggested-by: Mauro Carvalho Chehab mchehab@kernel.org Signed-off-by: Sakari Ailus sakari.ailus@linux.intel.com --- since v4:

- Use correct destination for error string (was broken in v4)

- Remove unneeded comment "/* subtract parenthesis and the space from the size */".

Documentation/core-api/printk-formats.rst | 16 +++++++ lib/test_printf.c | 17 ++++++++ lib/vsprintf.c | 51 +++++++++++++++++++++++ 3 files changed, 84 insertions(+)

diff --git a/Documentation/core-api/printk-formats.rst b/Documentation/core-api/printk-formats.rst index 6d26c5c6ac48..080262d2e030 100644 --- a/Documentation/core-api/printk-formats.rst +++ b/Documentation/core-api/printk-formats.rst @@ -565,6 +565,22 @@ For printing netdev_features_t.

Passed by reference.

+V4L2 and DRM FourCC code (pixel format) +--------------------------------------- + +:: + + %p4cc + +Print a FourCC code used by V4L2 or DRM, including format endianness and +its numerical value as hexadecimal. + +Passed by reference. + +Examples:: + + %p4cc BG12 little-endian (0x32314742) + Thanks ======

diff --git a/lib/test_printf.c b/lib/test_printf.c index 7ac87f18a10f..7fb042542660 100644 --- a/lib/test_printf.c +++ b/lib/test_printf.c @@ -649,6 +649,22 @@ static void __init fwnode_pointer(void) software_node_unregister(&softnodes[0]); }

+static void __init fourcc_pointer(void) +{ + struct { + u32 code; + char *str; + } const try[] = { + { 0x20104646, "FF(10) little-endian (0x20104646)", }, + { 0xa0104646, "FF(10) big-endian (0xa0104646)", }, + { 0x10111213, "(13)(12)(11)(10) little-endian (0x10111213)", }, + }; + unsigned int i; + + for (i = 0; i < ARRAY_SIZE(try); i++) + test(try[i].str, "%p4cc", &try[i].code); +} + static void __init errptr(void) { @@ -694,6 +710,7 @@ test_pointer(void) flags(); errptr(); fwnode_pointer(); + fourcc_pointer(); }

static void __init selftest(void) diff --git a/lib/vsprintf.c b/lib/vsprintf.c index 14c9a6af1b23..b07ee5b7de06 100644 --- a/lib/vsprintf.c +++ b/lib/vsprintf.c @@ -1733,6 +1733,54 @@ char *netdev_bits(char *buf, char *end, const void *addr, return special_hex_number(buf, end, num, size); }

+static noinline_for_stack +char *fourcc_string(char *buf, char *end, const u32 *fourcc, + struct printf_spec spec, const char *fmt) +{ + char output[sizeof("(xx)(xx)(xx)(xx) little-endian (0x01234567)")]; + char *p = output; + unsigned int i; + u32 val; + + if (fmt[1] != 'c' || fmt[2] != 'c') + return error_string(buf, end, "(%p4?)", spec); + + if (check_pointer(&buf, end, fourcc, spec)) + return buf; + + val = *fourcc & ~BIT(31); + + for (i = 0; i < sizeof(*fourcc); i++) { + unsigned char c = val >> (i * 8); + + /* Weed out spaces */ + if (c == ' ') + continue; + + /* Print non-control ASCII characters as-is */ + if (isascii(c) && isprint(c)) { + *p++ = c; + continue; + } + + *p++ = '('; + p = hex_byte_pack(p, c); + *p++ = ')'; + } + + strcpy(p, *fourcc & BIT(31) ? " big-endian" : " little-endian"); + p += strlen(p); + + *p++ = ' '; + *p++ = '('; + p = special_hex_number(p, output + sizeof(output) - 2, *fourcc, + sizeof(u32)); + *p++ = ')'; + *p = '\0'; + + return string(buf, end, output, spec); +} + static noinline_for_stack char *address_val(char *buf, char *end, const void *addr, struct printf_spec spec, const char *fmt) @@ -2162,6 +2210,7 @@ char *fwnode_string(char *buf, char *end, struct fwnode_handle *fwnode, * correctness of the format string and va_list arguments. * - 'K' For a kernel pointer that should be hidden from unprivileged users * - 'NF' For a netdev_features_t + * - '4cc' V4L2 or DRM FourCC code, with endianness and raw numerical value. * - 'h[CDN]' For a variable-length buffer, it prints it as a hex string with * a certain separator (' ' by default): * C colon @@ -2259,6 +2308,8 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr, return restricted_pointer(buf, end, ptr, spec); case 'N': return netdev_bits(buf, end, ptr, spec, fmt); + case '4': + return fourcc_string(buf, end, ptr, spec, fmt); case 'a': return address_val(buf, end, ptr, spec, fmt); case 'd':