* Thomas Zimmermann <tzimmermann@xxxxxxx> [240227 07:56]: > Am 27.02.24 um 08:06 schrieb Tony Lindgren: > > * 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? > > > > [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)); > > Great, that's exactly what I had in mind! OK :) > My proposal is to add this mmap function directly to omapdrm. I'll later > take care of integrating this into the overall framework. I have a few other > ideas in mind that are related to this issue. Ok? OK that sounds good to me, I'll post v3 set of patches. Regards, Tony
