From: Eric Engestrom <eric.engestrom@imgtec.com> To: Gerd Hoffmann <kraxel@redhat.com> Cc: "Michel Dänzer" <michel@daenzer.net>, "Daniel Vetter" <daniel.vetter@intel.com>, amd-gfx@lists.freedesktop.org, "open list" <linux-kernel@vger.kernel.org>, dri-devel@lists.freedesktop.org Subject: Re: [PATCH 3/6] drm: fourcc byteorder: add bigendian support to drm_mode_legacy_fb_format Date: Wed, 26 Apr 2017 14:28:01 +0100 [thread overview] Message-ID: <20170426132801.lldz7uwwlp3euozy@imgtec.com> (raw) In-Reply-To: <1493185990.23739.7.camel@redhat.com> 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 >
WARNING: multiple messages have this Message-ID (diff)
From: Eric Engestrom <eric.engestrom-1AXoQHu6uovQT0dZR+AlfA@public.gmane.org> To: Gerd Hoffmann <kraxel-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> Cc: dri-devel-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org, "Daniel Vetter" <daniel.vetter-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>, "Michel Dänzer" <michel-otUistvHUpPR7s880joybQ@public.gmane.org>, "open list" <linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, amd-gfx-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org Subject: Re: [PATCH 3/6] drm: fourcc byteorder: add bigendian support to drm_mode_legacy_fb_format Date: Wed, 26 Apr 2017 14:28:01 +0100 [thread overview] Message-ID: <20170426132801.lldz7uwwlp3euozy@imgtec.com> (raw) In-Reply-To: <1493185990.23739.7.camel-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> 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 > _______________________________________________ amd-gfx mailing list amd-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/amd-gfx
next prev parent reply other threads:[~2017-04-26 13:28 UTC|newest] Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top 2017-04-24 6:25 [PATCH 0/6] drm: tackle byteorder issues, take two Gerd Hoffmann 2017-04-24 6:25 ` [PATCH 1/6] drm: fourcc byteorder: drop DRM_FORMAT_BIG_ENDIAN Gerd Hoffmann 2017-04-24 6:25 ` Gerd Hoffmann 2017-04-24 6:25 ` [PATCH 2/6] drm: fourcc byteorder: add DRM_FORMAT_CPU_* Gerd Hoffmann 2017-04-24 6:25 ` Gerd Hoffmann 2017-04-24 6:25 ` [PATCH 3/6] drm: fourcc byteorder: add bigendian support to drm_mode_legacy_fb_format Gerd Hoffmann 2017-04-24 6:25 ` Gerd Hoffmann 2017-04-25 3:18 ` Michel Dänzer 2017-04-25 3:18 ` Michel Dänzer 2017-04-25 9:52 ` Ville Syrjälä 2017-04-26 2:00 ` Michel Dänzer 2017-04-26 2:00 ` Michel Dänzer 2017-04-26 14:30 ` Ville Syrjälä 2017-04-26 14:30 ` Ville Syrjälä 2017-04-26 5:53 ` Gerd Hoffmann 2017-04-26 5:53 ` Gerd Hoffmann 2017-04-26 9:21 ` Michel Dänzer 2017-04-26 9:21 ` Michel Dänzer 2017-04-26 12:11 ` Gerd Hoffmann 2017-04-26 12:11 ` Gerd Hoffmann 2017-04-27 0:52 ` Michel Dänzer 2017-04-27 0:52 ` Michel Dänzer 2017-04-27 6:45 ` Gerd Hoffmann 2017-04-27 6:45 ` Gerd Hoffmann 2017-04-27 7:02 ` Michel Dänzer 2017-04-28 10:02 ` Gerd Hoffmann 2017-04-28 10:02 ` Gerd Hoffmann 2017-04-26 13:28 ` Eric Engestrom [this message] 2017-04-26 13:28 ` Eric Engestrom 2017-04-26 13:57 ` Gerd Hoffmann 2017-04-26 13:57 ` Gerd Hoffmann 2017-04-24 6:25 ` [PATCH 4/6] drm: fourcc byteorder: adapt bochs-drm to drm_mode_legacy_fb_format update Gerd Hoffmann 2017-04-24 6:25 ` Gerd Hoffmann 2017-04-24 6:25 ` Gerd Hoffmann 2017-04-24 6:25 ` [PATCH 5/6] drm: fourcc byteorder: adapt virtio " Gerd Hoffmann 2017-04-24 6:25 ` Gerd Hoffmann 2017-04-24 6:25 ` Gerd Hoffmann 2017-04-24 6:25 ` [PATCH 6/6] drm: fourcc byteorder: virtio restrict to XRGB8888 Gerd Hoffmann 2017-04-24 6:25 ` Gerd Hoffmann [not found] ` <20170424062532.26722-1-kraxel-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> 2017-04-24 7:03 ` [PATCH 0/6] drm: tackle byteorder issues, take two Michel Dänzer [not found] ` <484f319e-c2b7-adc8-4ecf-537803cc2eee-otUistvHUpPR7s880joybQ@public.gmane.org> 2017-04-24 7:36 ` Gerd Hoffmann 2017-04-24 7:54 ` Michel Dänzer [not found] ` <f6555947-598f-0dfe-b15d-cda291778e8e-otUistvHUpPR7s880joybQ@public.gmane.org> 2017-04-24 14:26 ` Ville Syrjälä 2017-04-24 17:06 ` Daniel Stone [not found] ` <20170424142603.GX30290-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org> 2017-04-24 17:28 ` Ville Syrjälä 2017-04-25 0:49 ` Michel Dänzer [not found] ` <65ba8ab7-d647-4b9e-1e8c-aa6e9b1ff996-otUistvHUpPR7s880joybQ@public.gmane.org> 2017-04-25 9:50 ` Ville Syrjälä
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