[Intel-gfx] [PATCH 1/9] drm/i915/dsb: Replace HAS_DSB check with dsb->cmd_buf check

[Manna, Animesh]

On 30-01-2020 23:43, Souza, Jose wrote:
> On Wed, 2020-01-29 at 20:20 +0200, Ville Syrjala wrote:
>> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
>>
>> We may want to not use the DSB even if the platform has one.
>> So replace the HAS_DSB check in the _put() with a cmd_buf check
>> that will work in either case.
> Reviewed-by: José Roberto de Souza <jose.souza at intel.com>
>
>> Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
>> ---
>>   drivers/gpu/drm/i915/display/intel_dsb.c | 3 +--
>>   1 file changed, 1 insertion(+), 2 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/display/intel_dsb.c
>> b/drivers/gpu/drm/i915/display/intel_dsb.c
>> index 9dd18144a664..12776f09f227 100644
>> --- a/drivers/gpu/drm/i915/display/intel_dsb.c
>> +++ b/drivers/gpu/drm/i915/display/intel_dsb.c
>> @@ -160,9 +160,8 @@ intel_dsb_get(struct intel_crtc *crtc)
>>   void intel_dsb_put(struct intel_dsb *dsb)
>>   {
>>   	struct intel_crtc *crtc = container_of(dsb, typeof(*crtc),
>> dsb);
>> -	struct drm_i915_private *i915 = to_i915(crtc->base.dev);
>>   
>> -	if (!HAS_DSB(i915))
>> +	if (!dsb->cmd_buf)

Ville and Jose,

Have a concern here. In intel_dsb_get() if get failure during i915_gem_object_create_internal, i915_gem_object_ggtt_pin, i915_gem_object_pin_map then we may not have dsb->cmd_buf.
Then ref-count mechanism will break.
I feel HAS_DSB(i915) check is better than dsb->cmd_buf otherwise need to do some cleanup is intel_dsb_get() as well.

Regards,
Animesh

>>   		return;
>>   
>>   	if (WARN_ON(dsb->refcount == 0))
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