On 04/07/2020 15:52, Sam Ravnborg wrote:
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.
Hi Sam,
Yes, that's correct - I can confirm that the simplified diff below works:
diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c index 5609e164805f..83af05fac604 100644 --- a/drivers/gpu/drm/drm_fb_helper.c +++ b/drivers/gpu/drm/drm_fb_helper.c @@ -399,7 +399,7 @@ static void drm_fb_helper_dirty_blit_real(struct drm_fb_helper *fb_helper, 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]; }
I guess that the next step is to wait for advice from Gerd as to whether this is sufficient, or if other changes are required to allow non-shadow buffers to work on architectures similar to SPARC64 too.
ATB,
Mark.