Hi Mark.
On Sat, Jul 04, 2020 at 03:16:47PM +0100, Mark Cave-Ayland wrote:
On 04/07/2020 14:41, Sam Ravnborg wrote:
I think what is happening is that the bochs driver request a shadow copy for the frambuffer. And with the change to fbops we now use the cfb_ functions to write to the shadow framebuffer - which is not in any IO space. So this does not work.
So maybe all we need is the fix in drm_fb_helper_dirty_blit_real(). If you try to undo the change so fbops is set to &drm_fbdev_fb_ops, but keep the fix in drm_fb_helper_dirty_blit_real() how does it then behave?
Bingo! I just tried that and the framebuffer is now working under qemu-system-sparc64 again - thank you so much for the help! From what you said I guess drm_fb_helper_dirty_blit_real() is responsible syncing the shadow copy?
Below is the current working diff based upon your previous one: it certainly feels like the difference in memcpy() behaviour should be hidden away in fb_memcpy_tofb() or similar.
From your feedback so far I thnk the minimal fix would be like this:
--- a/drivers/gpu/drm/drm_fb_helper.c +++ b/drivers/gpu/drm/drm_fb_helper.c .. static void drm_fb_helper_dirty_blit_real(struct drm_fb_helper *fb_helper, size_t len = (clip->x2 - clip->x1) * cpp; unsigned int y;
for (y = clip->y1; y < clip->y2; y++) {
memcpy(dst, src, len);
fb_memcpy_tofb(dst, src, len); src += fb->pitches[0]; dst += fb->pitches[0]; }
(Hand edited, patch s not a valid syntax)
But I need feedback from someone that know all this a bit better to judge if this is an OK change. For once - this will only work with shadow buffers.
Sam
diff --git a/include/drm/drm_mode_config.h b/include/drm/drm_mode_config.h index 6c3ef49b46b3..dce9adf7d189 100644 --- a/include/drm/drm_mode_config.h +++ b/include/drm/drm_mode_config.h @@ -865,6 +865,15 @@ struct drm_mode_config { */ bool prefer_shadow_fbdev;
/*** @use_cfb_for_fbdev:** Use cfb variants of drm_fb_helper_cfb_{fillrect,copyarea,imageblit}* The cfb variants are required when the CPU do not allow direct* access to the framebuffer (for example sparc64)*/bool use_cfb_for_fbdev;/** * @quirk_addfb_prefer_xbgr_30bpp: *I did not find time to follow your instructions to test this myself with qemu - sorry.
No worries, I do appreciate that as a maintainer it can be hard to fit these things around life, family, job etc.
ATB,
Mark. _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel