On Mon, Feb 15, 2021 at 01:40:28PM +0200, Sakari Ailus wrote:

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.

This version I almost like, feel free to add Reviewed-by: From: Andy Shevchenko andriy.shevchenko@linux.intel.com after considering addressing below nit-picks.

Suggested-by: Mauro Carvalho Chehab mchehab@kernel.org Signed-off-by: Sakari Ailus sakari.ailus@linux.intel.com Reviewed-by: Petr Mladek pmladek@suse.com Reviewed-by: Sergey Senozhatsky sergey.senozhatsky@gmail.com

---

Documentation/core-api/printk-formats.rst | 16 ++++++++++ lib/test_printf.c | 17 ++++++++++ lib/vsprintf.c | 39 +++++++++++++++++++++++ scripts/checkpatch.pl | 6 ++-- 4 files changed, 76 insertions(+), 2 deletions(-)

diff --git a/Documentation/core-api/printk-formats.rst b/Documentation/core-api/printk-formats.rst index 160e710d992f..da2aa065dc42 100644 --- a/Documentation/core-api/printk-formats.rst +++ b/Documentation/core-api/printk-formats.rst @@ -567,6 +567,22 @@ 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)

No examples with spaces / non-printable / non-ascii characters

Thanks

diff --git a/lib/test_printf.c b/lib/test_printf.c index 7d60f24240a4..9848510a2786 100644 --- a/lib/test_printf.c +++ b/lib/test_printf.c @@ -647,6 +647,22 @@ static void __init fwnode_pointer(void) software_node_unregister_nodes(softnodes); }

+static void __init fourcc_pointer(void) +{

• struct {

• u32 code;
  

• char *str;
  

• } const try[] = {

• { 0x3231564e, "NV12 little-endian (0x3231564e)", },
  

• { 0xb231564e, "NV12 big-endian (0xb231564e)", },
  

• { 0x10111213, ".... 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) { @@ -692,6 +708,7 @@ 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 3b53c73580c5..432b5a2d1e90 100644 --- a/lib/vsprintf.c +++ b/lib/vsprintf.c @@ -1733,6 +1733,42 @@ 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("1234 little-endian (0x01234567)")];

1234 -> ABCD ? (Or XY12 to be closer to the reality)

• 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);
  

• /* Print non-control ASCII characters as-is, dot otherwise */
  

• *p++ = isascii(c) && isprint(c) ? c : '.';
  

• }
• 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 +2198,7 @@ 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 +2296,8 @@ 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':

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl index 92e888ed939f..79858e07d023 100755 --- a/scripts/checkpatch.pl +++ b/scripts/checkpatch.pl @@ -6557,9 +6557,11 @@ sub process { $specifier = $1; $extension = $2; $qualifier = $3;

• 			if ($extension !~ /[SsBKRraEehMmIiUDdgVCbGNOxtf]/ ||
  

• 			if ($extension !~ /[4SsBKRraEehMmIiUDdgVCbGNOxtf]/ ||
  		    ($extension eq "f" &&
  

• 			     defined $qualifier && $qualifier !~ /^w/)) {
  

• 			     defined $qualifier && $qualifier !~ /^w/) ||
  

• 			    ($extension eq "4" &&
  

• 			     defined $qualifier && $qualifier !~ /^cc/)) {
  			$bad_specifier = $specifier;
  			last;
  		}
  

-- 2.29.2