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

[Harry Wentland <harry.wentland-5C7GfCeVMHo@public.gmane.org>]

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

> Thanks,
> Andrey
> 
>>
>>> Thanks,
>>> Andrey
>>>
>>> On 2017-11-22 02:13 AM, S, Shirish wrote:
>>>> From: Shirish S <shirish.s@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@amd.com>
>>>> Reviewed-by: Roman Li <Roman.Li@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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> 
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