[Freedreno] [PATCH v4 03/20] drm: allow real encoder to be passed for drm_writeback_connector
Abhinav Kumar
quic_abhinavk at quicinc.com
Sun Apr 24 18:23:20 UTC 2022
On 4/24/2022 11:12 AM, Abhinav Kumar wrote:
> Hi Laurent
>
> On 4/24/2022 7:50 AM, Laurent Pinchart wrote:
>> Hi Abhinav,
>>
>> Thank you for the patch.
>>
>> On Fri, Apr 22, 2022 at 04:06:38PM -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.
>>>
>>> For existing clients, drm_writeback_connector_init() will use
>>> an internal_encoder under the hood and hence no changes will
>>> be needed.
>>>
>>> changes in v7:
>>> - move this change before the vc4 change in the series
>>> to minimize the changes to vendor drivers in drm core
>>> changes
>>
>> Why is this needed ? The drm_writeback_connector functions don't need
>> the drm_encoder after drm_writeback_connector_init() (or
>> drm_writeback_connector_init_with_encoder()) returns.
>>
>
> Sorry I didnt follow this comment. This change log is incorrect, so
> after changing the previous change in the series and modifying this, no
> further changes are needed to vc4, so I decided to drop the next change.
> So this change log is incorrect. I can remove this.
>
> Is that what you meant?
So till the previous change, the only user of
drm_writeback_connector_init_with_encoder() was
drm_writeback_connector_init() which was still passing its own
internal_encoder.
Only if the wb_connector->encoder is changed to a pointer, other vendor
drivers can pass their own encoder to
drm_writeback_connector_init_with_encoder().
Hence you are right that drm_writeback_connector functions do not need
drm_encoder after init() returns, but till this change is done, other
vendor drivers cannot directly call
drm_writeback_connector_init_with_encoder() because the encoder will not
be valid till then.
Hope this clarifies it.
>
>>> Signed-off-by: Abhinav Kumar <quic_abhinavk at quicinc.com>
>>> Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov at linaro.org>
>>> ---
>>> drivers/gpu/drm/drm_writeback.c | 18 ++++++++++++------
>>> drivers/gpu/drm/vc4/vc4_txp.c | 4 ++--
>>> include/drm/drm_writeback.h | 22 ++++++++++++++++++++--
>>> 3 files changed, 34 insertions(+), 10 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/drm_writeback.c
>>> b/drivers/gpu/drm/drm_writeback.c
>>> index 92658ad..0538674 100644
>>> --- a/drivers/gpu/drm/drm_writeback.c
>>> +++ b/drivers/gpu/drm/drm_writeback.c
>>> @@ -180,21 +180,21 @@ 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;
>>> }
>>> @@ -239,6 +239,12 @@ 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 3447eb6..7e063a9 100644
>>> --- a/drivers/gpu/drm/vc4/vc4_txp.c
>>> +++ b/drivers/gpu/drm/vc4/vc4_txp.c
>>> @@ -159,7 +159,7 @@ 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,
>>> connector.internal_encoder);
>>> }
>>> static inline struct vc4_txp *connector_to_vc4_txp(struct
>>> drm_connector *conn)
>>> @@ -507,7 +507,7 @@ 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 bb306fa..3fbae9d 100644
>>> --- a/include/drm/drm_writeback.h
>>> +++ b/include/drm/drm_writeback.h
>>> @@ -25,13 +25,31 @@ 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;
>>> +
>>> + /**
>>> + * @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 encoder;
>>> + struct drm_encoder internal_encoder;
>>> /**
>>> * @pixel_formats_blob_ptr:
>>
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