Re: [PATCH v6 3/3] drm/fourcc: Switch to %p4cc format modifier

[Daniel Vetter]

On Mon, Feb 8, 2021 at 9:20 PM Sakari Ailus
<sakari.ailus@xxxxxxxxxxxxxxx> wrote:
>
> Instead of constructing the FourCC code manually, use the %p4cc printk
> modifier to print it. Also leave a message to avoid using this function.
>
> The next step would be to convert the users to use %p4cc directly instead
> and removing the function.
>
> Signed-off-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>
> ---
>  drivers/gpu/drm/drm_fourcc.c | 16 +++-------------
>  1 file changed, 3 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_fourcc.c b/drivers/gpu/drm/drm_fourcc.c
> index 03262472059c..4ff40f2f27c0 100644
> --- a/drivers/gpu/drm/drm_fourcc.c
> +++ b/drivers/gpu/drm/drm_fourcc.c
> @@ -30,11 +30,6 @@
>  #include <drm/drm_device.h>
>  #include <drm/drm_fourcc.h>
>
> -static char printable_char(int c)
> -{
> -       return isascii(c) && isprint(c) ? c : '?';
> -}
> -
>  /**
>   * drm_mode_legacy_fb_format - compute drm fourcc code from legacy description
>   * @bpp: bits per pixels
> @@ -134,17 +129,12 @@ EXPORT_SYMBOL(drm_driver_legacy_fb_format);
>   * drm_get_format_name - fill a string with a drm fourcc format's name
>   * @format: format to compute name of
>   * @buf: caller-supplied buffer
> + *
> + * Please use %p4cc printk format modifier instead of this function.

I think would be nice if we could roll this out and outright delete
this one here ... Quick git grep says there's not that many, and %p4cc
is quite a bit shorter than what we have now.
-Daniel

>   */
>  const char *drm_get_format_name(uint32_t format, struct drm_format_name_buf *buf)
>  {
> -       snprintf(buf->str, sizeof(buf->str),
> -                "%c%c%c%c %s-endian (0x%08x)",
> -                printable_char(format & 0xff),
> -                printable_char((format >> 8) & 0xff),
> -                printable_char((format >> 16) & 0xff),
> -                printable_char((format >> 24) & 0x7f),
> -                format & DRM_FORMAT_BIG_ENDIAN ? "big" : "little",
> -                format);
> +       snprintf(buf->str, sizeof(buf->str), "%p4cc", &format);
>
>         return buf->str;
>  }
> --
> 2.29.2
>
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch