Hi Andy,
On Mon, Feb 15, 2021 at 03:31:29PM +0200, Andy Shevchenko wrote:
> 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@xxxxxxxxxxxxxxx>
> after considering addressing below nit-picks.
>
> > Suggested-by: Mauro Carvalho Chehab <mchehab@xxxxxxxxxx>
> > Signed-off-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>
> > Reviewed-by: Petr Mladek <pmladek@xxxxxxxx>
> > Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx>
> > ---
> > 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
I can sure add an example that has a space. But do you think I really
should add an example where invalid information is being printed?
>
> > +
> > 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)
I count in numbers... albeit the hexadecimal number there starts from zero.
I guess both would work though.
0123 would be consistent.
--
Regards,
Sakari Ailus
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