Messages in this thread | | | From | Geert Uytterhoeven <> | Date | Wed, 26 Jul 2023 14:04:13 +0200 | Subject | Re: [PATCH v5 2/2] drm/ssd130x: Allocate buffer in the plane's .atomic_check() callback |
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Hi Javier,
On Wed, Jul 26, 2023 at 12:55 PM Javier Martinez Canillas <javierm@redhat.com> wrote: > Drivers are not allowed to fail after drm_atomic_helper_swap_state() has > been called and the new atomic state is stored into the current sw state. > > Since the struct ssd130x_device .data_array is allocated in the encoder's > .atomic_enable callback, the operation can fail and this is after the new > state has been stored. So it can break an atomic mode settings assumption. > > Fix this by having custom helpers to allocate, duplicate and destroy the > plane state, that will take care of allocating and freeing these buffers. > > Suggested-by: Maxime Ripard <mripard@kernel.org> > Signed-off-by: Javier Martinez Canillas <javierm@redhat.com> > Acked-by: Maxime Ripard <mripard@kernel.org> > Tested-by: Geert Uytterhoeven <geert@linux-m68k.org> > --- > > Changes in v5: > - Add collected tags from Maxime and Geert. > - Update commit message to not mention the kernel oops (Geert Uytterhoeven). > - Drop Reported-by and Fixes tags (Geert Uytterhoeven). > - Update comment about buffer and data_array fields (Geert Uytterhoeven). > - Remove superfluous NULL check in ssd130x_fb_blit_rect() (Geert Uytterhoeven). > - Reset .buffer to NULL if .data_array allocation fails (Geert Uytterhoeven). > - Inline buffer alloc/free helper functions (Geert Uytterhoeven).
Thanks for the update!
> --- a/drivers/gpu/drm/solomon/ssd130x.c > +++ b/drivers/gpu/drm/solomon/ssd130x.c
> @@ -535,7 +550,8 @@ static int ssd130x_update_rect(struct ssd130x_device *ssd130x, struct drm_rect * > return ret; > } > > -static void ssd130x_clear_screen(struct ssd130x_device *ssd130x) > +static void ssd130x_clear_screen(struct ssd130x_device *ssd130x, > + struct ssd130x_plane_state *ssd130x_state) > { > struct drm_rect fullscreen = { > .x1 = 0, > @@ -544,21 +560,21 @@ static void ssd130x_clear_screen(struct ssd130x_device *ssd130x) > .y2 = ssd130x->height, > }; > > - ssd130x_update_rect(ssd130x, &fullscreen); > + ssd130x_update_rect(ssd130x, ssd130x_state, &fullscreen);
I've just realized another issue: since 49d7d581ceaf4cf8 ("drm/ssd130x: Don't allocate buffers on each plane update"). this no longer clears the screens, but just updates the hardware with the data in ssd130x_device.buffer, i.e. with the last image shown. So this should at least clear all of ssd130x_device.buffer before calling ssd130x_update_rect().
As it's a bit pointless to transpose a black image, a better fix would be to just clear ssd130x.data_array, and call the low-level hardware functions like ssd130x_update_rect() does.
> }
Gr{oetje,eeting}s,
Geert
-- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
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