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

From: Arnd Bergmann
Date: Fri Dec 16 2022 - 07:39:13 EST


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