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

[Abhinav Kumar]

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.

>>
>> 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) {
>>>
> 
> 
>