[PATCH] drm/amd/display: Align num_crtc to max_streams

[Harry Wentland]

On 2/7/23 08:00, Hamza Mahfooz wrote:
> 
> On 2/6/23 23:05, Tianci Yin wrote:
>> From: tiancyin <tianci.yin at amd.com>
>>
>> [Why]
>> Display pipe might be harvested on some SKUs, that cause the
>> adev->mode_info.num_crtc mismatch with the usable crtc number,
>> then below error dmesgs observed after GPU recover.
>>
>>    *ERROR* amdgpu_dm_set_crtc_irq_state: crtc is NULL at id :3
>>    *ERROR* amdgpu_dm_set_crtc_irq_state: crtc is NULL at id :3
>>    *ERROR* amdgpu_dm_set_crtc_irq_state: crtc is NULL at id :3
>>    *ERROR* amdgpu_dm_set_pflip_irq_state: crtc is NULL at id :3
>>    *ERROR* amdgpu_dm_set_pflip_irq_state: crtc is NULL at id :3
>>    *ERROR* amdgpu_dm_set_pflip_irq_state: crtc is NULL at id :3
>>    *ERROR* amdgpu_dm_set_pflip_irq_state: crtc is NULL at id :3
>>    *ERROR* amdgpu_dm_set_vupdate_irq_state: crtc is NULL at id :3
>>    *ERROR* amdgpu_dm_set_vupdate_irq_state: crtc is NULL at id :3
>>    *ERROR* amdgpu_dm_set_vupdate_irq_state: crtc is NULL at id :3
>>
>> [How]
>> The max_streams is limited number after pipe fuse, align num_crtc
>> to max_streams to eliminate the error logs.
>>
>> Signed-off-by: tiancyin <tianci.yin at amd.com>
>> ---
>>   drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 3 +++
>>   1 file changed, 3 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
>> index b31cfda30ff9..87ec2574cc09 100644
>> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
>> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
>> @@ -4285,6 +4285,9 @@ static int amdgpu_dm_initialize_drm_device(struct amdgpu_device *adev)
>>           break;
>>       }
>>   +    /* Adjust the crtc number according to the DCN pipe fuse. */
>> +    adev->mode_info.num_crtc = dm->dc->caps.max_streams;
> 
> This would introduce array-out-bounds issues, since there are arrays of
> size AMDGPU_MAX_CRTCS that use num_crtc as a bounds check.

>From what I can tell max_streams is always <= AMDGPU_MAX_CRTCS (6),
though we're not checking. Maybe it'd be good to check and print a
DRM_ERROR here if that's ever not the case (e.g., if we ever add
any new ASIC that has more streams).

Harry

> 
>> +
>>       for (i = 0; i < dm->dc->caps.max_streams; i++)
>>           if (amdgpu_dm_crtc_init(dm, mode_info->planes[i], i)) {
>>               DRM_ERROR("KMS: Failed to initialize crtc\n");
>