On 4/1/20 4:05 PM, Sakari Ailus wrote: > Add a printk modifier %ppf (for pixel format) for printing V4L2 and DRM > pixel formats denoted by 4ccs. The 4cc encoding is the same for both so > the same implementation can be used. > > Suggested-by: Mauro Carvalho Chehab <mchehab@xxxxxxxxxx> > Signed-off-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx> > --- > Documentation/core-api/printk-formats.rst | 11 +++++++++ > lib/vsprintf.c | 29 +++++++++++++++++++++++ > 2 files changed, 40 insertions(+) > > diff --git a/Documentation/core-api/printk-formats.rst b/Documentation/core-api/printk-formats.rst > index 8ebe46b1af39..b6249f513c09 100644 > --- a/Documentation/core-api/printk-formats.rst > +++ b/Documentation/core-api/printk-formats.rst > @@ -545,6 +545,17 @@ For printing netdev_features_t. > > Passed by reference. > > +V4L2 and DRM fourcc code (pixel format) > +--------------------------------------- > + > +:: > + > + %ppf > + > +Print a 4cc code used by V4L2 or DRM. FourCC appears to be the more-or-less official name (https://en.wikipedia.org/wiki/FourCC) I would explain about the -BE suffix for bigendian fourcc variants. > + > +Passed by reference. > + > Thanks > ====== > > diff --git a/lib/vsprintf.c b/lib/vsprintf.c > index 7c488a1ce318..b39f0ac317c5 100644 > --- a/lib/vsprintf.c > +++ b/lib/vsprintf.c > @@ -1721,6 +1721,32 @@ char *netdev_bits(char *buf, char *end, const void *addr, > return special_hex_number(buf, end, num, size); > } > > +static noinline_for_stack > +char *pixel_format_string(char *buf, char *end, const u32 *fourcc, > + struct printf_spec spec, const char *fmt) > +{ > + char ch[2] = { 0 }; This can just be '{ };' > + unsigned int i; > + > + if (check_pointer(&buf, end, fourcc, spec)) > + return buf; > + > + switch (fmt[1]) { > + case 'f': > + for (i = 0; i < sizeof(*fourcc); i++) { > + ch[0] = *fourcc >> (i << 3); You need to AND with 0x7f, otherwise a big endian fourcc (bit 31 is set) will look wrong. Also, each character is standard 7 bit ascii, bit 7 isn't used except to indicate a BE variant. > + buf = string(buf, end, ch, spec); > + } > + > + if (*fourcc & BIT(31)) > + buf = string(buf, end, "-BE", spec); > + > + return buf; > + default: > + return error_string(buf, end, "(%pp?)", spec); > + } > +} > + > static noinline_for_stack > char *address_val(char *buf, char *end, const void *addr, > struct printf_spec spec, const char *fmt) > @@ -2131,6 +2157,7 @@ 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 > + * - 'pf' V4L2 or DRM pixel format. I'd say 'FourCC format' instead of 'pixel format'. > * - 'h[CDN]' For a variable-length buffer, it prints it as a hex string with > * a certain separator (' ' by default): > * C colon > @@ -2223,6 +2250,8 @@ 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 'p': > + return pixel_format_string(buf, end, ptr, spec, fmt); > case 'a': > return address_val(buf, end, ptr, spec, fmt); > case 'd': > Regards, Hans
