Re: [PATCH] drm/amd/display: fix dp_retrieve_lttpr_cap return code

[Arnd Bergmann]

On Thu, Dec 15, 2022, at 18:56, Michel Dänzer wrote:
> On 12/15/22 17:37, Arnd Bergmann wrote:
/amd/display/dc/core/dc_link_dp.c
>> index af9411ee3c74..95dbfa4e996a 100644
>> --- a/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c
>> +++ b/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c
>> @@ -5095,7 +5095,7 @@ enum dc_status dp_retrieve_lttpr_cap(struct dc_link 
>> *link)
>>      bool vbios_lttpr_interop = link->dc->caps.vbios_lttpr_aware;
>>  
>>      if (!vbios_lttpr_interop || 
>> !link->dc->caps.extended_aux_timeout_support)
>> -            return false;
>> +            return DC_OK;
>
>               return status;
>
> seems more appropriate. (Otherwise the status = DC_ERROR_UNEXPECTED 
> initialization has no effect)

Ok, makes sense. I'd also remove the unused initialization in that
case though:

 enum dc_status dp_retrieve_lttpr_cap(struct dc_link *link)
 {
        uint8_t lttpr_dpcd_data[8];
-       enum dc_status status = DC_ERROR_UNEXPECTED;
-       bool is_lttpr_present = false;
+       enum dc_status status;
+       bool is_lttpr_present;
 
        /* Logic to determine LTTPR support*/
        bool vbios_lttpr_interop = link->dc->caps.vbios_lttpr_aware;
 
        if (!vbios_lttpr_interop || 
!link->dc->caps.extended_aux_timeout_support)
-               return false;
+               return DC_ERROR_UNEXPECTED;
 
        /* By reading LTTPR capability, RX assumes that we will enable
         * LTTPR extended aux timeout if LTTPR is present.

I'll send that as a v2 once that passes my build test and nobody
has further suggestions.

       Arnd