Re: [PATCH v2 14/17] drm/msm/dpu: add the writeback connector layer

[Abhinav Kumar <quic_abhinavk@quicinc.com>]

On 4/20/2022 12:52 AM, Dmitry Baryshkov wrote:
> On 20/04/2022 04:46, Abhinav Kumar wrote:
>> Introduce the dpu_writeback module which serves as the
>> interface between dpu operations and the drm_writeback.
>>
>> This module manages the connector related operations for
>> dpu writeback.
>>
>> changes in v2:
>>     - start using drm_writeback_connector_init_with_encoder()
>>     - drop unnecessary arguments from dpu_writeback_init()
>>     - rebase on msm-next tip and remove usage of priv->connectors
>>
>> Signed-off-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
>> ---
>>   drivers/gpu/drm/msm/Makefile                  |  1 +
>>   drivers/gpu/drm/msm/disp/dpu1/dpu_writeback.c | 68 
>> +++++++++++++++++++++++++++
>>   drivers/gpu/drm/msm/disp/dpu1/dpu_writeback.h | 25 ++++++++++
>>   3 files changed, 94 insertions(+)
>>   create mode 100644 drivers/gpu/drm/msm/disp/dpu1/dpu_writeback.c
>>   create mode 100644 drivers/gpu/drm/msm/disp/dpu1/dpu_writeback.h
>>
>> diff --git a/drivers/gpu/drm/msm/Makefile b/drivers/gpu/drm/msm/Makefile
>> index 0387f22..66395ee 100644
>> --- a/drivers/gpu/drm/msm/Makefile
>> +++ b/drivers/gpu/drm/msm/Makefile
>> @@ -80,6 +80,7 @@ msm-$(CONFIG_DRM_MSM_DPU) += \
>>       disp/dpu1/dpu_plane.o \
>>       disp/dpu1/dpu_rm.o \
>>       disp/dpu1/dpu_vbif.o \
>> +    disp/dpu1/dpu_writeback.o
>>   msm-$(CONFIG_DRM_MSM_MDSS) += \
>>       msm_mdss.o \
>> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_writeback.c 
>> b/drivers/gpu/drm/msm/disp/dpu1/dpu_writeback.c
>> new file mode 100644
>> index 0000000..526d884
>> --- /dev/null
>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_writeback.c
>> @@ -0,0 +1,68 @@
>> +// SPDX-License-Identifier: GPL-2.0-only
>> +/*
>> + * Copyright (c) 2022 Qualcomm Innovation Center, Inc. All rights 
>> reserved.
>> + */
>> +
>> +#include "dpu_writeback.h"
>> +
>> +static int dpu_wb_conn_get_modes(struct drm_connector *connector)
>> +{
>> +    struct drm_device *dev = connector->dev;
>> +
>> +    return drm_add_modes_noedid(connector, dev->mode_config.max_width,
>> +            dev->mode_config.max_height);
>> +}
>> +
>> +static const struct drm_connector_funcs dpu_wb_conn_funcs = {
>> +    .reset = drm_atomic_helper_connector_reset,
>> +    .fill_modes = drm_helper_probe_single_connector_modes,
>> +    .destroy = drm_connector_cleanup,
>> +    .atomic_duplicate_state = 
>> drm_atomic_helper_connector_duplicate_state,
>> +    .atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
>> +};
>> +
>> +static int dpu_wb_conn_prepare_job(struct drm_writeback_connector 
>> *connector,
>> +        struct drm_writeback_job *job)
>> +{
>> +    if (!job->fb)
>> +        return 0;
>> +
>> +    dpu_encoder_prepare_wb_job(connector->encoder, job);
>> +
>> +    return 0;
>> +}
>> +
>> +static void dpu_wb_conn_cleanup_job(struct drm_writeback_connector 
>> *connector,
>> +        struct drm_writeback_job *job)
>> +{
>> +    if (!job->fb)
>> +        return;
>> +
>> +    dpu_encoder_cleanup_wb_job(connector->encoder, job);
>> +}
>> +
>> +static const struct drm_connector_helper_funcs 
>> dpu_wb_conn_helper_funcs = {
>> +    .get_modes = dpu_wb_conn_get_modes,
>> +    .prepare_writeback_job = dpu_wb_conn_prepare_job,
>> +    .cleanup_writeback_job = dpu_wb_conn_cleanup_job,
>> +};
>> +
>> +int dpu_writeback_init(struct drm_device *dev, struct drm_encoder *enc,
>> +        const u32 *format_list, u32 num_formats)
>> +{
>> +    struct dpu_wb_connector *dpu_wb_conn;
>> +    int rc = 0;
>> +
>> +    dpu_wb_conn = devm_kzalloc(dev->dev, sizeof(*dpu_wb_conn), 
>> GFP_KERNEL);
>> +
>> +    drm_connector_helper_add(&dpu_wb_conn->base.base, 
>> &dpu_wb_conn_helper_funcs);
>> +
>> +    /* DPU initializes the encoder and sets it up completely for 
>> writeback
>> +     * cases and hence should use the new API 
>> drm_writeback_connector_init_with_encoder
>> +     * to initialize the writeback connector
>> +     */
>> +    rc = drm_writeback_connector_init_with_encoder(dev, 
>> &dpu_wb_conn->base, enc,
>> +            &dpu_wb_conn_funcs, format_list, num_formats);
>> +
>> +    return rc;
>> +}
>> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_writeback.h 
>> b/drivers/gpu/drm/msm/disp/dpu1/dpu_writeback.h
>> new file mode 100644
>> index 0000000..05aff05
>> --- /dev/null
>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_writeback.h
>> @@ -0,0 +1,25 @@
>> +/* SPDX-License-Identifier: GPL-2.0-only */
>> +/*
>> + * Copyright (c) 2022 Qualcomm Innovation Center, Inc. All rights 
>> reserved.
>> + */
>> +
>> +#ifndef _DPU_WRITEBACK_H
>> +#define _DPU_WRITEBACK_H
>> +
>> +#include <drm/drm_crtc.h>
>> +#include <drm/drm_file.h>
>> +#include <drm/drm_probe_helper.h>
>> +#include <drm/drm_writeback.h>
>> +
>> +#include "msm_drv.h"
>> +#include "dpu_kms.h"
>> +#include "dpu_encoder_phys.h"
>> +
>> +struct dpu_wb_connector {
>> +    struct drm_writeback_connector base;
>> +};
> 
> Do you plan to add more fields to this struct? If not, we can probably 
> drop it and use struct drm_writeback_connector directly.

Glad you asked about it. I was expecting this question because it looks 
like a very "light" struct.

Yes, we do plan to expand this as we will keep adding writeback features 
sequentially now to make it ready for this to be absorbed downstream 
completely.

> 
>> +
>> +int dpu_writeback_init(struct drm_device *dev, struct drm_encoder *enc,
>> +        const u32 *format_list, u32 num_formats);
>> +
>> +#endif /*_DPU_WRITEBACK_H */
> 
>