* Tony Lindgren <tony@xxxxxxxxxxx> [240226 13:26]: > * Thomas Zimmermann <tzimmermann@xxxxxxx> [240226 09:10]: > > Am 26.02.24 um 10:01 schrieb Tomi Valkeinen: > > > On 26/02/2024 10:26, Tomi Valkeinen wrote: > > > > How is it broken? I don't usually use the console (or fbdev) but > > > > enabling it now, it seems to work fine for me, on DRA76 EVM with > > > > HDMI output. > > > > Omapdrm implements drm_framebuffer_funcs.dirty withomap_framebuffer_dirty(). > > AFAIK DRM semantics requires to run the dirty helper after writing to the > > framebuffer's memory. Userspace does this via the DIRTYFB ioctl. [1] But (at > > least) for correctness the console needs to do the same. > > > > [1] https://elixir.bootlin.com/linux/v6.7.6/source/drivers/gpu/drm/drm_ioctl.c#L679 > > Yes I noticed console not updating and bisected it down to the two > commits listed. I did the bisect on a droid4 though with command mode > LCD. I did not test with HDMI, will give that a try too. I can reproduce the cache issue with Tomi's omapfb-tests [2] below: while true; do dd if=/dev/urandom of=/dev/fb0 ~/src/omapfb-tests/test sleep 1 done That produces short random data stripes on the test image. > > > After applying your patches, I see a lot of cache-related artifacts on > > > the screen when updating the fb. > > > > I guess we might need a dma-specific mmap helper to make this work > > correctly. Comparing the difference between drm_gem_mmap_obj() and fb_deferred_io_mmap(), the following test patch makes the cache issue go away for me. Not sure if this can be set based on some flag, or if we need a separate fb_deferred_io_wc_mmap() or something like that? Regards, Tony [2] https://github.com/tomba/omapfb-tests 8< -------------------- diff --git a/drivers/video/fbdev/core/fb_defio.c b/drivers/video/fbdev/core/fb_defio.c --- a/drivers/video/fbdev/core/fb_defio.c +++ b/drivers/video/fbdev/core/fb_defio.c @@ -224,6 +224,7 @@ static const struct address_space_operations fb_deferred_io_aops = { int fb_deferred_io_mmap(struct fb_info *info, struct vm_area_struct *vma) { vma->vm_page_prot = pgprot_decrypted(vma->vm_page_prot); + vma->vm_page_prot = pgprot_writecombine(vm_get_page_prot(vma->vm_flags)); vma->vm_ops = &fb_deferred_io_vm_ops; vm_flags_set(vma, VM_DONTEXPAND | VM_DONTDUMP);
