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

[Harry Wentland]

On 2017-11-27 09:37 AM, Andrey Grodzovsky wrote:
> 
> 
> 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

This function just seems to mislabeled. decide_fbc might be better. It's only called from enable_fbc to decide whether or not to do FBC.

Roma, would it make sense to rename this function to avoid confusion?

Harry

> 
> 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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>>>>>> amd-gfx at lists.freedesktop.org
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>