[PATCH v2 7/9] drm/msm/dpu: check for overflow in _dpu_crtc_setup_lm_bounds()

[Dmitry Baryshkov]

On Mon, Jun 03, 2024 at 02:24:27PM -0700, Abhinav Kumar wrote:
> 
> 
> On 6/3/2024 2:16 PM, Dmitry Baryshkov wrote:
> > On Mon, 3 Jun 2024 at 23:57, Abhinav Kumar <quic_abhinavk at quicinc.com> wrote:
> > > 
> > > 
> > > 
> > > On 6/2/2024 2:39 PM, Dmitry Baryshkov wrote:
> > > > Check in _dpu_crtc_setup_lm_bounds() that CRTC width is not overflowing
> > > > LM requirements.
> > > > 
> > > > Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov at linaro.org>
> > > > ---
> > > >    drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c | 15 ++++++++++++---
> > > >    1 file changed, 12 insertions(+), 3 deletions(-)
> > > > 
> > > > diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
> > > > index e3b1e5f55a92..c5e874a3656a 100644
> > > > --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
> > > > +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
> > > > @@ -711,12 +711,13 @@ void dpu_crtc_complete_commit(struct drm_crtc *crtc)
> > > >        _dpu_crtc_complete_flip(crtc);
> > > >    }
> > > > 
> > > > -static void _dpu_crtc_setup_lm_bounds(struct drm_crtc *crtc,
> > > > +static int _dpu_crtc_setup_lm_bounds(struct drm_crtc *crtc,
> > > >                struct drm_crtc_state *state)
> > > 
> > > Perhaps now we need to rename this to _dpu_crtc_setup_and_check_lm_bounds()?
> > 
> > Ack, I'll rename it.
> > 
> > > 
> > > Also, prior to this change, we never had a bounds check for each LM
> > > which we should have had . Does this qualify for a Fixes tag?
> > 
> > Probably no. We currently have a limit in the drm_mode_config, which
> > ensures that the CRTC isn't too wide.
> > 
> 
> The limit in drm_mode_config is to ensure we will not go beyond
> 2*max_mixer_width for the mode as we support only upto 2 LMs.
> 
> This check is making sure that even for the single LM, we do not go beyond
> the max_mixer_width which is valid imo.

For the case where 2*LM mode is not possible? Yes, it seems to be a
valid case. But in such case I'd prefer to rework this patch and pull it
to the top of the series. I'll take a look.

> 
> > > 
> > > With those two questions addressed,
> > > 
> > > Reviewed-by: Abhinav Kumar <quic_abhinavk at quicinc.com>
> > > 
> > > >    {
> > > >        struct dpu_crtc_state *cstate = to_dpu_crtc_state(state);
> > > >        struct drm_display_mode *adj_mode = &state->adjusted_mode;
> > > >        u32 crtc_split_width = adj_mode->hdisplay / cstate->num_mixers;
> > > > +     struct dpu_kms *dpu_kms = _dpu_crtc_get_kms(crtc);
> > > >        int i;
> > > > 
> > > >        for (i = 0; i < cstate->num_mixers; i++) {
> > > > @@ -727,7 +728,12 @@ static void _dpu_crtc_setup_lm_bounds(struct drm_crtc *crtc,
> > > >                r->y2 = adj_mode->vdisplay;
> > > > 
> > > >                trace_dpu_crtc_setup_lm_bounds(DRMID(crtc), i, r);
> > > > +
> > > > +             if (drm_rect_width(r) > dpu_kms->catalog->caps->max_mixer_width)
> > > > +                     return -E2BIG;
> > > >        }
> > > 
> > > > +
> > > > +     return 0;
> > > >    }
> > > > 
> > > >    static void _dpu_crtc_get_pcc_coeff(struct drm_crtc_state *state,
> > > > @@ -1195,8 +1201,11 @@ static int dpu_crtc_atomic_check(struct drm_crtc *crtc,
> > > >        if (crtc_state->active_changed)
> > > >                crtc_state->mode_changed = true;
> > > > 
> > > > -     if (cstate->num_mixers)
> > > > -             _dpu_crtc_setup_lm_bounds(crtc, crtc_state);
> > > > +     if (cstate->num_mixers) {
> > > > +             rc = _dpu_crtc_setup_lm_bounds(crtc, crtc_state);
> > > > +             if (rc)
> > > > +                     return rc;
> > > > +     }
> > > > 
> > > >        /* FIXME: move this to dpu_plane_atomic_check? */
> > > >        drm_atomic_crtc_state_for_each_plane_state(plane, pstate, crtc_state) {
> > > > 
> > 
> > 
> > 

-- 
With best wishes
Dmitry