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

[Harry Wentland]

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

> 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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>