Hi Andy,
Thanks for the comments.
On Fri, Apr 03, 2020 at 12:31:03PM +0300, Andy Shevchenko wrote:
On Fri, Apr 03, 2020 at 12:11:56PM +0300, 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.
...
+static noinline_for_stack +char *fourcc_string(char *buf, char *end, const u32 *fourcc,
struct printf_spec spec, const char *fmt)+{
+#define FOURCC_STRING_BE "-BE"
- char s[sizeof(*fourcc) + sizeof(FOURCC_STRING_BE)] = { 0 };
I guess it makes it too complicated.
The above also clearly binds the size to the data that is expected to contain there. I'd prefer keeping it as-is. And yes, 8 would be correct, too.
char s[8];
- if (check_pointer(&buf, end, fourcc, spec))
return buf;- if (fmt[1] != 'c' || fmt[2] != 'c')
return error_string(buf, end, "(%p4?)", spec);
- put_unaligned_le32(*fourcc & ~BIT(31), s);
Can you elaborate what the difference in output with this bit set over cleared? I.o.w. why don't we need to put it as BE and for LE case addd "-LE"?
The established practice is that big endian formats have "-BE" suffix whereas the little endian ones have nothing. (At least when it comes to V4L2.)
- if (*fourcc & BIT(31))
strscpy(s + sizeof(*fourcc), FOURCC_STRING_BE,sizeof(FOURCC_STRING_BE));We know the size, and we may put '\0' as well if (*fourcc & BIT(31)) strscpy(&s[4], "-BE", sizeof("-BE")); else strscpy(&s[4], "", sizeof(""));
The rest of the struct memory has already been set to zero in variable declaration.