[PATCH] drm/amd/display: check plane state before validating fbc

[Andrey Grodzovsky]

On 11/27/2017 09:28 AM, Harry Wentland wrote:
>
> On 2017-11-27 07:38 AM, Andrey Grodzovsky wrote:
>>
>> On 11/26/2017 11:57 AM, Harry Wentland wrote:
>>> On 2017-11-24 05:07 PM, Andrey Grodzovsky wrote:
>>>> The patch is good, but why validate_fbc is being called from dce110_apply_ctx_to_hw (atomic_commit) ? It should be called from atomic_check.
>>>>
>>> Ideally yes, but I don't think this has any impact on bandwidth and mode validation, i.e. we should never fail to apply an atomic state, no matter whether we do FBC. If we let user-mode decide whether to do FBC or not it would need to be a property and check in atomic_check but I don't think it makes any sense to expose this outside DC.
>>>
>>> Harry
>> I see, as long as enable_fbc return code is ignored as it is today that ok.
>>
> Maybe we just shouldn't return an error code here. dce110_apply_ctx_to_hw probably shouldn't return one either then, and apply_single_controller_ctx_to_hw_plane (just a couple lines before enable_fbc) shouldn't fail. I might have to look at those sometime.
>
> Harry

Well, it seems wrong to have a validation function which never fails or 
it's return value ignored, maybe just merge validate_fbc into enable_fbc 
, drop all the error codes and rename enable_fbc into try_enable_fbc

Thanks,
Andrey

>
>> Thanks,
>> Andrey
>>
>>>> Thanks,
>>>> Andrey
>>>>
>>>> On 2017-11-22 02:13 AM, S, Shirish wrote:
>>>>> From: Shirish S <shirish.s at amd.com>
>>>>>
>>>>> While validation fbc, array_mode of the pipe is accessed without checking plane_state exists for it.
>>>>> Causing to null pointer dereferencing followed by reboot when a crtc associated with external display(not
>>>>> connected) is page flipped.
>>>>>
>>>>> This patch adds a check for plane_state before using it to validate fbc.
>>>>>
>>>>> Signed-off-by: Shirish S <shirish.s at amd.com>
>>>>> Reviewed-by: Roman Li <Roman.Li at amd.com>
>>>>> ---
>>>>>     drivers/gpu/drm/amd/display/dc/dce110/dce110_hw_sequencer.c | 4 ++++
>>>>>     1 file changed, 4 insertions(+)
>>>>>
>>>>> diff --git a/drivers/gpu/drm/amd/display/dc/dce110/dce110_hw_sequencer.c b/drivers/gpu/drm/amd/display/dc/dce110/dce110_hw_sequencer.c
>>>>> index ee3b944..a6cd63a 100644
>>>>> --- a/drivers/gpu/drm/amd/display/dc/dce110/dce110_hw_sequencer.c
>>>>> +++ b/drivers/gpu/drm/amd/display/dc/dce110/dce110_hw_sequencer.c
>>>>> @@ -1724,6 +1724,10 @@ static enum dc_status validate_fbc(struct dc *dc,
>>>>>         if (pipe_ctx->stream->sink->link->psr_enabled)
>>>>>             return DC_ERROR_UNEXPECTED;
>>>>>     +    /* Nothing to compress */
>>>>> +    if (!pipe_ctx->plane_state)
>>>>> +        return DC_ERROR_UNEXPECTED;
>>>>> +
>>>>>         /* Only for non-linear tiling */
>>>>>         if (pipe_ctx->plane_state->tiling_info.gfx8.array_mode == DC_ARRAY_LINEAR_GENERAL)
>>>>>             return DC_ERROR_UNEXPECTED;
>>>>> -- 
>>>>> 2.7.4
>>>>>
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