On Wednesday, 2017-04-26 07:53:10 +0200, Gerd Hoffmann wrote:
On Di, 2017-04-25 at 12:18 +0900, Michel Dänzer wrote:
On 24/04/17 03:25 PM, Gerd Hoffmann wrote:
Return correct fourcc codes on bigendian. Drivers must be adapted to this change.
Signed-off-by: Gerd Hoffmann kraxel@redhat.com
Just to reiterate, this won't work for the radeon driver, which programs the GPU to use (effectively, per the current definition that these are little endian GPU formats) DRM_FORMAT_XRGB8888 with pre-R600 and DRM_FORMAT_BGRX8888 with >= R600.
Hmm, ok, how does bigendian fbdev emulation work on pre-R600 then?
+#ifdef __BIG_ENDIAN
- switch (bpp) {
- case 8:
fmt = DRM_FORMAT_C8;break;- case 24:
fmt = DRM_FORMAT_BGR888;break;BTW, endianness as a concept cannot apply to 8 or 24 bpp formats.
I could move the 8 bpp case out of the #ifdef somehow, but code readability will suffer then I think ...
How about something like this?
uint32_t drm_mode_legacy_fb_format(uint32_t bpp, uint32_t depth) { uint32_t fmt; #ifdef __BIG_ENDIAN enum { LITTLE_ENDIAN = 0 }; #else enum { LITTLE_ENDIAN = 1 }; #endif /* ... */
(using an enum for compile-time constness)
and then fmt = DRM_FORMAT_ARGB8888; becomes fmt = LITTLE_ENDIAN ? DRM_FORMAT_ARGB8888 : DRM_FORMAT_BGRA8888;
Might be easier to read than duplicating the whole switch?
For 24 we have different byte orderings, but yes, you can't switch from one to the other with byteswapping. Probably one of the reasons why this format is pretty much out of fashion these days ...
cheers, Gerd