Messages in this thread | | | Date | Mon, 27 Apr 2020 18:30:46 +0300 | From | Andy Shevchenko <> | Subject | Re: [RESEND PATCH v3 1/1] lib/vsprintf: Add support for printing V4L2 and DRM fourccs |
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On Mon, Apr 27, 2020 at 05:53:03PM +0300, 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.
4cc is more generic than pixel format.
...
> +V4L2 and DRM FourCC code (pixel format) > +--------------------------------------- > + > +:: > + > + %p4cc
Missed examples.
> +Print a FourCC code used by V4L2 or DRM, including format endianness and > +its numerical value as hexadecimal.
...
> +static noinline_for_stack > +char *fourcc_string(char *buf, char *end, const u32 *__fourcc, > + struct printf_spec spec, const char *fmt) > +{ > +#define FOURCC_HEX_CHAR_STR "(xx)" > +#define FOURCC_BIG_ENDIAN_STR " big-endian" > +#define FOURCC_LITTLE_ENDIAN_STR " little-endian" > +#define FOURCC_HEX_NUMBER " (0x01234567)"
Where are #undef:s?
> +#define FOURCC_STRING_MAX \ > + FOURCC_HEX_CHAR_STR FOURCC_HEX_CHAR_STR FOURCC_HEX_CHAR_STR \ > + FOURCC_HEX_CHAR_STR FOURCC_LITTLE_ENDIAN_STR FOURCC_HEX_NUMBER
> + struct printf_spec my_spec = { > + .type = FORMAT_TYPE_UINT, > + .field_width = 2, > + .flags = SMALL, > + .base = 16, > + .precision = -1, > + };
Seems like close enough to bus_spec.
> + char __s[sizeof(FOURCC_STRING_MAX)]; > + char *s = __s; > + unsigned int i; > + /* > + * The 31st bit defines the endianness of the data, so save its printing > + * for later. > + */ > + u32 fourcc = *__fourcc & ~BIT(31); > + int ret; > + > + if (check_pointer(&buf, end, __fourcc, spec)) > + return buf; > + > + if (fmt[1] != 'c' || fmt[2] != 'c') > + return error_string(buf, end, "(%p4?)", spec); > + > + for (i = 0; i < sizeof(fourcc); i++, fourcc >>= 8) { > + unsigned char c = fourcc; > + > + /* Weed out spaces */ > + if (c == ' ') > + continue; > + > + /* Print non-control characters as-is */ > + if (c > ' ') { > + *s = c; > + s++; > + continue; > + }
> + if (WARN_ON_ONCE(sizeof(__s) < > + (s - __s) + sizeof(FOURCC_HEX_CHAR_STR)))
Why WARN?!
> + break; > + > + *s = '('; > + s++; > + s = number(s, s + 2, c, my_spec); > + *s = ')'; > + s++; > + } > + > + ret = strscpy(s, *__fourcc & BIT(31) ? FOURCC_BIG_ENDIAN_STR > + : FOURCC_LITTLE_ENDIAN_STR, > + sizeof(__s) - (s - __s));
> + if (!WARN_ON_ONCE(ret < 0))
Ditto.
> + s += ret;
> + if (!WARN_ON_ONCE(sizeof(__s) < > + (s - __s) + sizeof(FOURCC_HEX_NUMBER))) {
Ditto.
> + *s = ' '; > + s++; > + *s = '('; > + s++; > + /* subtract parentheses and the space from the size */ > + special_hex_number(s, s + sizeof(FOURCC_HEX_NUMBER) - 3, > + *__fourcc, sizeof(u32)); > + s += sizeof(u32) * 2 + 2 /* 0x */; > + *s = ')'; > + s++; > + *s = '\0'; > + } > + > + return string(buf, end, __s, spec);
This looks overengineered. Why everyone will need so long strings to be printed?
> +}
-- With Best Regards, Andy Shevchenko
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