[Freedreno] [PATCH v6 4/4] drm: allow real encoder to be passed for drm_writeback_connector

Abhinav Kumar quic_abhinavk at quicinc.com
Tue Apr 5 17:08:59 UTC 2022


Hi Laurent

On 4/5/2022 10:02 AM, Laurent Pinchart wrote:
> Hi Abhinav,
> 
> On Tue, Apr 05, 2022 at 09:53:57AM -0700, Abhinav Kumar wrote:
>> On 4/5/2022 9:47 AM, Laurent Pinchart wrote:
>>> On Mon, Apr 04, 2022 at 11:43:37AM -0700, Rob Clark wrote:
>>>> On Fri, Apr 1, 2022 at 8:38 AM Laurent Pinchart wrote:
>>>>> On Thu, Mar 31, 2022 at 05:12:13PM -0700, Abhinav Kumar wrote:
>>>>>> For some vendor driver implementations, display hardware can
>>>>>> be shared between the encoder used for writeback and the physical
>>>>>> display.
>>>>>>
>>>>>> In addition resources such as clocks and interrupts can
>>>>>> also be shared between writeback and the real encoder.
>>>>>>
>>>>>> To accommodate such vendor drivers and hardware, allow
>>>>>> real encoder to be passed for drm_writeback_connector.
>>>>>>
>>>>>> changes in v6:
>>>>>>         - assign the encoder inside
>>>>>>           drm_writeback_connector_init_with_encoder() for
>>>>>>           better readability
>>>>>>         - improve some documentation for internal encoder
>>>>>>
>>>>>> Co-developed-by: Kandpal Suraj <suraj.kandpal at intel.com>
>>>>>> Signed-off-by: Kandpal Suraj <suraj.kandpal at intel.com>
>>>>>> Signed-off-by: Abhinav Kumar <quic_abhinavk at quicinc.com>
>>>>>> ---
>>>>>>    drivers/gpu/drm/drm_writeback.c | 18 ++++++++++++------
>>>>>>    drivers/gpu/drm/vc4/vc4_txp.c   | 14 ++++++++------
>>>>>>    include/drm/drm_writeback.h     | 21 +++++++++++++++++++--
>>>>>
>>>>> Please split this in two patches, one for the DRM core and one for the
>>>>> VC4 driver. This applies to most patches as a general rule, with the
>>>>> main exception being API refactoring that requires changing the
>>>>> implementation and all its users in a single patch.
>>>>
>>>> But this *is* API refactoring ;-)
>>>
>>> Partly at least :-) Looking at the API change itself, wouldn't we
>>> minimize the extra changes to vc4 if we moved this patch before 3/4 ?
>>
>> I can move all the changes done in vc4 except below part to the change
>> 3/4 itself because that way I can show usage of vc4->drm_enc with the
>> new API. Let me know if that works.
> 
> What I meant is moving the API refactoring from 4/4 before the current
> 3/4, with minimal changes to vc4 there (only to avoid introducing a
> bisection breakge), and then move most of the vc4 changes from this
> patch to the current 3/4 (which will become 4/4). If that's what you
> meant too, it sounds good to me.

The API refactoring part in this patch is tied closely with changing the 
wb_connector's encoder to a pointer which breaks vc4.

I have not made any additional refactoring changes here.

So I am not sure how to decouple this more.

Thanks

Abhinav


> 
>> The only part which will remain is the below one:
>>
>> @@ -523,7 +525,7 @@  static int vc4_txp_bind(struct device *dev, struct
>> device *master, void *data)
>>    	if (ret)
>>    		return ret;
>>
>> -	encoder = &txp->connector.encoder;
>> +	encoder = txp->connector.encoder;
>>    	encoder->possible_crtcs = drm_crtc_mask(crtc);
>>
>> Since i dont know vc4 driver very well, I was not sure of a good way to
>> decouple this dependency.
>>
>> Let me know if that works.
>>
>>>>>>    3 files changed, 39 insertions(+), 14 deletions(-)
>>>>>>
>>>>>> diff --git a/drivers/gpu/drm/drm_writeback.c b/drivers/gpu/drm/drm_writeback.c
>>>>>> index 797223c..7f72109 100644
>>>>>> --- a/drivers/gpu/drm/drm_writeback.c
>>>>>> +++ b/drivers/gpu/drm/drm_writeback.c
>>>>>> @@ -179,21 +179,21 @@ int drm_writeback_connector_init(struct drm_device *dev,
>>>>>>    {
>>>>>>         int ret = 0;
>>>>>>
>>>>>> -     drm_encoder_helper_add(&wb_connector->encoder, enc_helper_funcs);
>>>>>> +     drm_encoder_helper_add(&wb_connector->internal_encoder, enc_helper_funcs);
>>>>>>
>>>>>> -     wb_connector->encoder.possible_crtcs = possible_crtcs;
>>>>>> +     wb_connector->internal_encoder.possible_crtcs = possible_crtcs;
>>>>>>
>>>>>> -     ret = drm_encoder_init(dev, &wb_connector->encoder,
>>>>>> +     ret = drm_encoder_init(dev, &wb_connector->internal_encoder,
>>>>>>                                &drm_writeback_encoder_funcs,
>>>>>>                                DRM_MODE_ENCODER_VIRTUAL, NULL);
>>>>>>         if (ret)
>>>>>>                 return ret;
>>>>>>
>>>>>> -     ret = drm_writeback_connector_init_with_encoder(dev, wb_connector, &wb_connector->encoder,
>>>>>> -                     con_funcs, formats, n_formats);
>>>>>> +     ret = drm_writeback_connector_init_with_encoder(dev, wb_connector,
>>>>>> +                     &wb_connector->internal_encoder, con_funcs, formats, n_formats);
>>>>>>
>>>>>>         if (ret)
>>>>>> -             drm_encoder_cleanup(&wb_connector->encoder);
>>>>>> +             drm_encoder_cleanup(&wb_connector->internal_encoder);
>>>>>>
>>>>>>         return ret;
>>>>>>    }
>>>>>> @@ -238,6 +238,12 @@ int drm_writeback_connector_init_with_encoder(struct drm_device *dev,
>>>>>>         struct drm_mode_config *config = &dev->mode_config;
>>>>>>         int ret = create_writeback_properties(dev);
>>>>>>
>>>>>> +     /*
>>>>>> +      * Assign the encoder passed to this API to the wb_connector's encoder.
>>>>>> +      * For drm_writeback_connector_init(), this shall be the internal_encoder
>>>>>> +      */
>>>>>> +     wb_connector->encoder = enc;
>>>>>> +
>>>>>>         if (ret != 0)
>>>>>>                 return ret;
>>>>>>
>>>>>> diff --git a/drivers/gpu/drm/vc4/vc4_txp.c b/drivers/gpu/drm/vc4/vc4_txp.c
>>>>>> index 5e53f02..a9b4f83 100644
>>>>>> --- a/drivers/gpu/drm/vc4/vc4_txp.c
>>>>>> +++ b/drivers/gpu/drm/vc4/vc4_txp.c
>>>>>> @@ -151,6 +151,8 @@ struct vc4_txp {
>>>>>>
>>>>>>         struct platform_device *pdev;
>>>>>>
>>>>>> +     struct drm_encoder drm_enc;
>>>>>> +
>>>>>>         struct drm_writeback_connector connector;
>>>>>>
>>>>>>         void __iomem *regs;
>>>>>> @@ -159,7 +161,7 @@ struct vc4_txp {
>>>>>>
>>>>>>    static inline struct vc4_txp *encoder_to_vc4_txp(struct drm_encoder *encoder)
>>>>>>    {
>>>>>> -     return container_of(encoder, struct vc4_txp, connector.encoder);
>>>>>> +     return container_of(encoder, struct vc4_txp, drm_enc);
>>>>>>    }
>>>>>>
>>>>>>    static inline struct vc4_txp *connector_to_vc4_txp(struct drm_connector *conn)
>>>>>> @@ -499,9 +501,9 @@ static int vc4_txp_bind(struct device *dev, struct device *master, void *data)
>>>>>>
>>>>>>         wb_conn = &txp->connector;
>>>>>>
>>>>>> -     drm_encoder_helper_add(&wb_conn->encoder, &vc4_txp_encoder_helper_funcs);
>>>>>> +     drm_encoder_helper_add(&txp->drm_enc, &vc4_txp_encoder_helper_funcs);
>>>>>>
>>>>>> -     ret = drm_encoder_init(drm, &wb_conn->encoder,
>>>>>> +     ret = drm_encoder_init(drm, &txp->drm_enc,
>>>>>>                         &vc4_txp_encoder_funcs,
>>>>>>                         DRM_MODE_ENCODER_VIRTUAL, NULL);
>>>>>>
>>>>>> @@ -511,10 +513,10 @@ static int vc4_txp_bind(struct device *dev, struct device *master, void *data)
>>>>>>         drm_connector_helper_add(&wb_conn->base,
>>>>>>                                  &vc4_txp_connector_helper_funcs);
>>>>>>
>>>>>> -     ret = drm_writeback_connector_init_with_encoder(drm, wb_conn, &wb_conn->encoder,
>>>>>> +     ret = drm_writeback_connector_init_with_encoder(drm, wb_conn, &txp->drm_enc,
>>>>>>                         &vc4_txp_connector_funcs, drm_fmts, ARRAY_SIZE(drm_fmts));
>>>>>>         if (ret) {
>>>>>> -             drm_encoder_cleanup(&wb_conn->encoder);
>>>>>> +             drm_encoder_cleanup(&txp->drm_enc);
>>>>>>                 return ret;
>>>>>>         }
>>>>>>
>>>>>> @@ -523,7 +525,7 @@ static int vc4_txp_bind(struct device *dev, struct device *master, void *data)
>>>>>>         if (ret)
>>>>>>                 return ret;
>>>>>>
>>>>>> -     encoder = &txp->connector.encoder;
>>>>>> +     encoder = txp->connector.encoder;
>>>>>>         encoder->possible_crtcs = drm_crtc_mask(crtc);
>>>>>>
>>>>>>         ret = devm_request_irq(dev, irq, vc4_txp_interrupt, 0,
>>>>>> diff --git a/include/drm/drm_writeback.h b/include/drm/drm_writeback.h
>>>>>> index 4795024..3f5c330 100644
>>>>>> --- a/include/drm/drm_writeback.h
>>>>>> +++ b/include/drm/drm_writeback.h
>>>>>> @@ -25,15 +25,32 @@ struct drm_writeback_connector {
>>>>>>         struct drm_connector base;
>>>>>>
>>>>>>         /**
>>>>>> -      * @encoder: Internal encoder used by the connector to fulfill
>>>>>> +      * @encoder: handle to drm_encoder used by the connector to fulfill
>>>>>>          * the DRM framework requirements. The users of the
>>>>>>          * @drm_writeback_connector control the behaviour of the @encoder
>>>>>>          * by passing the @enc_funcs parameter to drm_writeback_connector_init()
>>>>>>          * function.
>>>>>> +      *
>>>>>> +      * For some vendor drivers, the hardware resources are shared between
>>>>>> +      * writeback encoder and rest of the display pipeline.
>>>>>> +      * To accommodate such cases, encoder is a handle to the real encoder
>>>>>> +      * hardware.
>>>>>> +      *
>>>>>> +      * For current existing writeback users, this shall continue to be the
>>>>>> +      * embedded encoder for the writeback connector.
>>>>>>          */
>>>>>> -     struct drm_encoder encoder;
>>>>>> +     struct drm_encoder *encoder;
>>>>>>
>>>>>>         /**
>>>>>> +      * @internal_encoder: internal encoder used by writeback when
>>>>>> +      * drm_writeback_connector_init() is used.
>>>>>> +      * @encoder will be assigned to this for those cases
>>>>>> +      *
>>>>>> +      * This will be unused when drm_writeback_connector_init_with_encoder()
>>>>>> +      * is used.
>>>>>> +      */
>>>>>> +     struct drm_encoder internal_encoder;
>>>>>> +     /**
>>>>>>          * @pixel_formats_blob_ptr:
>>>>>>          *
>>>>>>          * DRM blob property data for the pixel formats list on writeback
> 


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