Re: [PATCH] drm/meson: fix max mode_config height/width

[Daniel Vetter]

On Thu, Oct 4, 2018 at 5:05 PM Neil Armstrong <narmstrong@xxxxxxxxxxxx> wrote:
>
> On 04/10/2018 12:09, Daniel Vetter wrote:
> > On Thu, Oct 04, 2018 at 10:42:43AM +0200, Neil Armstrong wrote:
> >> The mode_config max_width/max_height determines the maximum framebuffer
> >> size the pixel reader can handle. But the values were set thinking they
> >> were determining the maximum screen dimensions.
> >>
> >> This patch changes the values to the maximum height/width the CANVAS block
> >> can handle rounded to some coherent values.
> >>
> >> Fixes: a41e82e6c457 ("drm/meson: Add support for components")
> >> Signed-off-by: Neil Armstrong <narmstrong@xxxxxxxxxxxx>
> >
> > It's both. Grep for all the callers of ->fill_modes and you'll see that
> > this limit is also used to filter max screen sizes.
> >
> > If you want to change this, then I think we need a new
> > mode_config.fb_max_width/height, which if non-zero, would extend the limit
> > for fbs.
> >
> > There's also the problem that if you extend this for fbs, then there's no
> > check anymore in the atomic_commit paths (or legacy modeset), so that
> > needs to be addressed somehow too.
>
> What about adding optionals mode_config.fb_max_width/height and update
> drm_internal_framebuffer_create() to use these if non-0 or fallback
> to the mode_config max_width/max_height.

That's what I meant. Except you also need to then fix the gap you've
opened in atomic_check, and validate the mode size against
mode_config.max_width/height.
-Daniel

>
> Neil
>
> >
> > Bunch of igt to make sure we're not missing anything would be sweet on
> > top, e.g. e.g. trying to set a mode over the limit and making sure it
> > fails.
> >
> > Cheers, Daniel
> >
> >> ---
> >>  drivers/gpu/drm/meson/meson_drv.c | 4 ++--
> >>  1 file changed, 2 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/drivers/gpu/drm/meson/meson_drv.c b/drivers/gpu/drm/meson/meson_drv.c
> >> index d344312..2e29968 100644
> >> --- a/drivers/gpu/drm/meson/meson_drv.c
> >> +++ b/drivers/gpu/drm/meson/meson_drv.c
> >> @@ -243,8 +243,8 @@ static int meson_drv_bind_master(struct device *dev, bool has_components)
> >>              goto free_drm;
> >>
> >>      drm_mode_config_init(drm);
> >> -    drm->mode_config.max_width = 3840;
> >> -    drm->mode_config.max_height = 2160;
> >> +    drm->mode_config.max_width = 16384;
> >> +    drm->mode_config.max_height = 8192;
> >>      drm->mode_config.funcs = &meson_mode_config_funcs;
> >>
> >>      /* Hardware Initialization */
> >> --
> >> 2.7.4
> >>
> >> _______________________________________________
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> >
>
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch