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Subject: Re: [PATCH] media: staging: rkisp1: cap: refactor enable/disable
 stream to allow multistreaming
From:   Helen Koike <helen.koike@collabora.com>
To:     Dafna Hirschfeld <dafna.hirschfeld@collabora.com>,
        linux-media@vger.kernel.org
Cc:     laurent.pinchart@ideasonboard.com, hverkuil@xs4all.nl,
        kernel@collabora.com, sakari.ailus@linux.intel.com,
        linux-rockchip@lists.infradead.org, mchehab@kernel.org,
        tfiga@chromium.org, linux-kernel@vger.kernel.org
References: <20201015195746.264722-1-helen.koike@collabora.com>
 <8b31c5a3-9b01-9536-384a-b06d9a0a2e1a@collabora.com>
 <b8e18639-febf-9e3f-3525-7fb52a612727@collabora.com>
Message-ID: <32295a2e-c3b0-fffc-5e23-8dbdbb83f757@collabora.com>
Date:   Mon, 19 Oct 2020 13:02:23 -0300
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Hello,

On 10/16/20 3:11 PM, Helen Koike wrote:
> 
> 
> On 10/16/20 11:28 AM, Dafna Hirschfeld wrote:
>> Hi,
>>
>> Am 15.10.20 um 21:57 schrieb Helen Koike:
>>> Allow streaming from self picture path and main picture path at the same
>>> time.
>>>
>>> Take care for s_stream() callbacks to not be called twice.
>>> When starting a stream, s_stream(true) shouldn't be called for the isp
>>> and the sensor if the other stream is already enabled (since it was
>>> already called).
>>> When stopping a stream, s_stream(false) shouldn't be called for isp and
>>> the sensor if the other stream is still enabled.
>>>
>>> Remove the callback function scheme for navigating through the topology,
>>> simplifying the code, improving readability, while calling
>>> media_pipeline_{start,stop}() in the right order.
>>>
>>> Remove multistreaming item from the TODO list.
>>>
>>> Signed-off-by: Helen Koike <helen.koike@collabora.com>
>>>
>>> ---
>>> Hello,
>>>
>>> Since we didn't reach an agreement on the helpers in the core[1], I'm
>>> sending this patch to fix this limitation only for rkisp1.
>>>
>>> [1] https://patchwork.linuxtv.org/project/linux-media/cover/20200415013044.1778572-1-helen.koike@collabora.com/
>>>
>>> If we decide to add the helpers in the future, we can clean up drivers
>>> even more, but I don't want to block this feature.
>>>
>>> Overview of the patch:
>>> ======================
>>>
>>> * Rename rkisp1_stream_{start,stop}() to
>>>    rkisp1_cap_stream_{enable,disable}() to clarify the difference between
>>>    other stream enable/disable functions
>>>
>>> * Implement rkisp1_pipeline_stream_{enable,disable}() to replace
>>>    rkisp1_pipeline_{enable,disable}_cb() and rkisp1_pipeline_sink_walk(),
>>>    which were removed.
>>>
>>> * Call rkisp1_cap_stream_{enable,disable}() from
>>>    rkisp1_pipeline_stream_{enable,disable}() for better
>>>    unwind handling and function name semantics.
>>>
>>> * Call media_pipeline_{start,stop}() in the right order.
>>>
>>> * Remove item from TODO list (I also reviewed the use of the
>>>    is_streaming var in the code and lgtm).
>>>
>>> This patch was tested on rockpi4 board with:
>>> ============================================
>>>
>>> "media-ctl" "-d" "platform:rkisp1" "-r"
>>> "media-ctl" "-d" "platform:rkisp1" "-l" "'imx219 4-0010':0 -> 'rkisp1_isp':0 [1]"
>>> "media-ctl" "-d" "platform:rkisp1" "-l" "'rkisp1_isp':2 -> 'rkisp1_resizer_selfpath':0 [1]"
>>> "media-ctl" "-d" "platform:rkisp1" "-l" "'rkisp1_isp':2 -> 'rkisp1_resizer_mainpath':0 [1]"
>>>
>>> "media-ctl" "-d" "platform:rkisp1" "--set-v4l2" '"imx219 4-0010":0 [fmt:SRGGB10_1X10/1640x1232]'
>>>
>>> "media-ctl" "-d" "platform:rkisp1" "--set-v4l2" '"rkisp1_isp":0 [fmt:SRGGB10_1X10/1640x1232 crop: (0,0)/1600x1200]'
>>> "media-ctl" "-d" "platform:rkisp1" "--set-v4l2" '"rkisp1_isp":2 [fmt:YUYV8_2X8/1600x1200 crop: (0,0)/1500x1100]'
>>>
>>> "media-ctl" "-d" "platform:rkisp1" "--set-v4l2" '"rkisp1_resizer_selfpath":0 [fmt:YUYV8_2X8/1500x1100 crop: (300,400)/1400x1000]'
>>> "media-ctl" "-d" "platform:rkisp1" "--set-v4l2" '"rkisp1_resizer_selfpath":1 [fmt:YUYV8_2X8/900x800]'
>>>
>>> "v4l2-ctl" "-z" "platform:rkisp1" "-d" "rkisp1_selfpath" "-v" "width=900,height=800,"
>>> "v4l2-ctl" "-z" "platform:rkisp1" "-d" "rkisp1_selfpath" "-v" "pixelformat=422P"
>>>
>>> "media-ctl" "-d" "platform:rkisp1" "--set-v4l2" '"rkisp1_resizer_mainpath":0 [fmt:YUYV8_2X8/1500x1100 crop: (300,400)/1400x1000]'
>>> "media-ctl" "-d" "platform:rkisp1" "--set-v4l2" '"rkisp1_resizer_mainpath":1 [fmt:YUYV8_2X8/900x800]'
>>>
>>> "v4l2-ctl" "-z" "platform:rkisp1" "-d" "rkisp1_mainpath" "-v" "width=900,height=800,"
>>> "v4l2-ctl" "-z" "platform:rkisp1" "-d" "rkisp1_mainpath" "-v" "pixelformat=422P"
>>>
>>> sleep 1
>>>
>>> time v4l2-ctl "-z" "platform:rkisp1" "-d" "rkisp1_mainpath" "--stream-mmap" "--stream-count" "100" &
>>> time v4l2-ctl "-z" "platform:rkisp1" "-d" "rkisp1_selfpath" "--stream-mmap" "--stream-count" "100" &
>>>
>>> wait
>>> echo "Completed"
>>>
>>> Thanks
>>> Helen
>>> ---
>>>   drivers/staging/media/rkisp1/TODO             |   3 -
>>>   drivers/staging/media/rkisp1/rkisp1-capture.c | 227 +++++++++---------
>>>   2 files changed, 113 insertions(+), 117 deletions(-)
>>>
>>> diff --git a/drivers/staging/media/rkisp1/TODO b/drivers/staging/media/rkisp1/TODO
>>> index e7c8398fc2cef..a2dd0ad951c25 100644
>>> --- a/drivers/staging/media/rkisp1/TODO
>>> +++ b/drivers/staging/media/rkisp1/TODO
>>> @@ -1,9 +1,6 @@
>>>   * Fix pad format size for statistics and parameters entities.
>>>   * Fix checkpatch errors.
>>>   * Add uapi docs. Remember to add documentation of how quantization is handled.
>>> -* streaming paths (mainpath and selfpath) check if the other path is streaming
>>> -in several places of the code, review this, specially that it doesn't seem it
>>> -supports streaming from both paths at the same time.
>>>     NOTES:
>>>   * All v4l2-compliance test must pass.
>>> diff --git a/drivers/staging/media/rkisp1/rkisp1-capture.c b/drivers/staging/media/rkisp1/rkisp1-capture.c
>>> index b6f497ce3e95c..254936873c6c1 100644
>>> --- a/drivers/staging/media/rkisp1/rkisp1-capture.c
>>> +++ b/drivers/staging/media/rkisp1/rkisp1-capture.c
>>> @@ -830,71 +830,43 @@ static void rkisp1_return_all_buffers(struct rkisp1_capture *cap,
>>>   }
>>>     /*
>>> - * rkisp1_pipeline_sink_walk - Walk through the pipeline and call cb
>>> - * @from: entity at which to start pipeline walk
>>> - * @until: entity at which to stop pipeline walk
>>> - *
>>> - * Walk the entities chain starting at the pipeline video node and stop
>>> - * all subdevices in the chain.
>>> - *
>>> - * If the until argument isn't NULL, stop the pipeline walk when reaching the
>>> - * until entity. This is used to disable a partially started pipeline due to a
>>> - * subdev start error.
>>> + * Most of registers inside rockchip ISP1 have shadow register since
>>> + * they must be not be changed during processing a frame.
>>> + * Usually, each sub-module updates its shadow register after
>>> + * processing the last pixel of a frame.
>>>    */
>>> -static int rkisp1_pipeline_sink_walk(struct media_entity *from,
>>> -                     struct media_entity *until,
>>> -                     int (*cb)(struct media_entity *from,
>>> -                           struct media_entity *curr))
>>> +static void rkisp1_cap_stream_enable(struct rkisp1_capture *cap)
>>>   {
>>> -    struct media_entity *entity = from;
>>> -    struct media_pad *pad;
>>> -    unsigned int i;
>>> -    int ret;
>>> -
>>> -    while (1) {
>>> -        pad = NULL;
>>> -        /* Find remote source pad */
>>> -        for (i = 0; i < entity->num_pads; i++) {
>>> -            struct media_pad *spad = &entity->pads[i];
>>> -
>>> -            if (!(spad->flags & MEDIA_PAD_FL_SINK))
>>> -                continue;
>>> -            pad = media_entity_remote_pad(spad);
>>> -            if (pad && is_media_entity_v4l2_subdev(pad->entity))
>>> -                break;
>>> -        }
>>> -        if (!pad || !is_media_entity_v4l2_subdev(pad->entity))
>>> -            break;
>>> +    struct rkisp1_device *rkisp1 = cap->rkisp1;
>>> +    struct rkisp1_capture *other = &rkisp1->capture_devs[cap->id ^ 1];
>>>   -        entity = pad->entity;
>>> -        if (entity == until)
>>> -            break;
>>> +    cap->ops->set_data_path(cap);
>>> +    cap->ops->config(cap);
>>>   -        ret = cb(from, entity);
>>> -        if (ret)
>>> -            return ret;
>>> +    /* Setup a buffer for the next frame */
>>> +    spin_lock_irq(&cap->buf.lock);
>>> +    rkisp1_set_next_buf(cap);
>>> +    cap->ops->enable(cap);
>>> +    /* It's safe to config ACTIVE and SHADOW regs for the
>>> +     * first stream. While when the second is starting, do NOT
>>> +     * force update because it also update the first one.
>>> +     *
>>> +     * The latter case would drop one more buf(that is 2) since
>>> +     * there's not buf in shadow when the second FE received. This's
>>> +     * also required because the second FE maybe corrupt especially
>>> +     * when run at 120fps.
>>> +     */
>>> +    if (!other->is_streaming) {
>>> +        /* force cfg update */
>>> +        rkisp1_write(rkisp1,
>>> +                 RKISP1_CIF_MI_INIT_SOFT_UPD, RKISP1_CIF_MI_INIT);
>>> +        rkisp1_set_next_buf(cap);
>>>       }
>>> -
>>> -    return 0;
>>> -}
>>> -
>>> -static int rkisp1_pipeline_disable_cb(struct media_entity *from,
>>> -                      struct media_entity *curr)
>>> -{
>>> -    struct v4l2_subdev *sd = media_entity_to_v4l2_subdev(curr);
>>> -
>>> -    return v4l2_subdev_call(sd, video, s_stream, false);
>>> -}
>>> -
>>> -static int rkisp1_pipeline_enable_cb(struct media_entity *from,
>>> -                     struct media_entity *curr)
>>> -{
>>> -    struct v4l2_subdev *sd = media_entity_to_v4l2_subdev(curr);
>>> -
>>> -    return v4l2_subdev_call(sd, video, s_stream, true);
>>> +    spin_unlock_irq(&cap->buf.lock);
>>> +    cap->is_streaming = true;
>>>   }
>>>   -static void rkisp1_stream_stop(struct rkisp1_capture *cap)
>>> +static void rkisp1_cap_stream_disable(struct rkisp1_capture *cap)
>>>   {
>>>       int ret;
>>>   @@ -911,6 +883,81 @@ static void rkisp1_stream_stop(struct rkisp1_capture *cap)
>>>       }
>>>   }
>>>   +/*
>>> + * rkisp1_pipeline_stream_disable - disable nodes in the pipeline
>>> + *
>>> + * Call s_stream(false) in the reverse order from
>>> + * rkisp1_pipeline_stream_enable() and disable the DMA engine.
>>> + * Should be called before media_pipeline_stop()
>>> + */
>>> +static void rkisp1_pipeline_stream_disable(struct rkisp1_capture *cap)
>>> +    __must_hold(&cap->rkisp1->stream_lock)
>>> +{
>>> +    struct rkisp1_device *rkisp1 = cap->rkisp1;
>>> +
>>> +    rkisp1_cap_stream_disable(cap);
>>> +
>>> +    /*
>>> +     * If the other capture is streaming, isp and sensor nodes shouldn't
>>> +     * be disabled, skip them.
>>> +     */
>>> +    if (rkisp1->pipe.streaming_count < 2) {
>>> +        v4l2_subdev_call(rkisp1->active_sensor->sd, video, s_stream,
>>> +                 false);
>>> +        v4l2_subdev_call(&rkisp1->isp.sd, video, s_stream, false);
>>> +    }
>>> +
>>> +    v4l2_subdev_call(&rkisp1->resizer_devs[cap->id].sd, video, s_stream,
>>> +             false);
>>
>> I wonder if the order of the disable matters. If it should be from the sensor up to the
>> capture then we should call 'rkisp1_cap_stream_disable' at the end of this
>> function.

The only issue I saw was if I enable the sensor before the ISP.
Even if the order in disabling the capture doesn't matter much, it is nice to
keep the logic, thanks for this comment.

>>
>>> +}
>>> +
>>> +/*
>>> + * rkisp1_pipeline_stream_enable - enable nodes in the pipeline
>>> + *
>>> + * Enable the DMA Engine and call s_stream(true) through the pipeline.
>>> + * Should be called after media_pipeline_start()
>>> + */
>>> +static int rkisp1_pipeline_stream_enable(struct rkisp1_capture *cap)
>>> +    __must_hold(&cap->rkisp1->stream_lock)
>>> +{
>>> +    struct rkisp1_device *rkisp1 = cap->rkisp1;
>>> +    int ret;
>>> +
>>> +    rkisp1_cap_stream_enable(cap);
>>> +
>>> +    ret = v4l2_subdev_call(&rkisp1->resizer_devs[cap->id].sd, video,
>>> +                   s_stream, true);
>>> +    if (ret)
>>> +        return ret;
>>
>> In case of error here, shouldn't we call 'rkisp1_cap_stream_disable'?
> 
> Yes, thanks for catching it :)
> 
>>
>>> +
>>> +    /*
>>> +     * If the other capture is streaming, isp and sensor nodes are already
>>> +     * enabled, skip them.
>>> +     */
>>> +    if (rkisp1->pipe.streaming_count > 1)
>>> +        return 0;
>>> +
>>> +    ret = v4l2_subdev_call(&rkisp1->isp.sd, video, s_stream, true);
>>> +    if (ret)
>>> +        goto err_disable_rsz;
>>> +
>>> +    ret = v4l2_subdev_call(rkisp1->active_sensor->sd, video, s_stream,
>>> +                   true);
>>> +    if (ret)
>>> +        goto err_disable_isp;
>>> +
>>> +    return 0;
>>> +
>>> +err_disable_isp:
>>> +    v4l2_subdev_call(&rkisp1->isp.sd, video, s_stream, false);
>>> +err_disable_rsz:
>>> +    v4l2_subdev_call(&rkisp1->resizer_devs[cap->id].sd, video, s_stream,
>>> +             false);
>>> +    rkisp1_cap_stream_disable(cap);
>>> +
>>> +    return ret;
>>> +}
>>> +
>>>   static void rkisp1_vb2_stop_streaming(struct vb2_queue *queue)
>>>   {
>>>       struct rkisp1_capture *cap = queue->drv_priv;
>>> @@ -920,13 +967,8 @@ static void rkisp1_vb2_stop_streaming(struct vb2_queue *queue)
>>>         mutex_lock(&cap->rkisp1->stream_lock);
>>>   -    rkisp1_stream_stop(cap);
>>> +    rkisp1_pipeline_stream_disable(cap);
>>>       media_pipeline_stop(&node->vdev.entity);
>>> -    ret = rkisp1_pipeline_sink_walk(&node->vdev.entity, NULL,
>>> -                    rkisp1_pipeline_disable_cb);
>>> -    if (ret)
>>> -        dev_err(rkisp1->dev,
>>> -            "pipeline stream-off failed error:%d\n", ret);
>>>         rkisp1_return_all_buffers(cap, VB2_BUF_STATE_ERROR);
>>>   @@ -940,43 +982,6 @@ static void rkisp1_vb2_stop_streaming(struct vb2_queue *queue)
>>>       mutex_unlock(&cap->rkisp1->stream_lock);
>>>   }
>>>   -/*
>>> - * Most of registers inside rockchip ISP1 have shadow register since
>>> - * they must be not be changed during processing a frame.
>>> - * Usually, each sub-module updates its shadow register after
>>> - * processing the last pixel of a frame.
>>> - */
>>> -static void rkisp1_stream_start(struct rkisp1_capture *cap)
>>> -{
>>> -    struct rkisp1_device *rkisp1 = cap->rkisp1;
>>> -    struct rkisp1_capture *other = &rkisp1->capture_devs[cap->id ^ 1];
>>> -
>>> -    cap->ops->set_data_path(cap);
>>> -    cap->ops->config(cap);
>>> -
>>> -    /* Setup a buffer for the next frame */
>>> -    spin_lock_irq(&cap->buf.lock);
>>> -    rkisp1_set_next_buf(cap);
>>> -    cap->ops->enable(cap);
>>> -    /* It's safe to config ACTIVE and SHADOW regs for the
>>> -     * first stream. While when the second is starting, do NOT
>>> -     * force update because it also update the first one.
>>> -     *
>>> -     * The latter case would drop one more buf(that is 2) since
>>> -     * there's not buf in shadow when the second FE received. This's
>>> -     * also required because the second FE maybe corrupt especially
>>> -     * when run at 120fps.
>>> -     */
>>> -    if (!other->is_streaming) {
>>> -        /* force cfg update */
>>> -        rkisp1_write(rkisp1,
>>> -                 RKISP1_CIF_MI_INIT_SOFT_UPD, RKISP1_CIF_MI_INIT);
>>> -        rkisp1_set_next_buf(cap);
>>> -    }
>>> -    spin_unlock_irq(&cap->buf.lock);
>>> -    cap->is_streaming = true;
>>> -}
>>> -
>>>   static int
>>>   rkisp1_vb2_start_streaming(struct vb2_queue *queue, unsigned int count)
>>>   {
>>> @@ -1001,28 +1006,22 @@ rkisp1_vb2_start_streaming(struct vb2_queue *queue, unsigned int count)
>>>           goto err_pipe_pm_put;
>>>       }
>>>  
>>
>> The previous code with the 'rkisp1_pipeline_sink_walk' only followed enabled links.
>> We should probably first check if the link between the resizer and the isp is enabled
>> and also between the isp to the sensor. and return -EPIPE if not.
> 
> Very good point, yes, I'll fix this in v2.

Actually this is not required, since resizer and isp sink pads use MEDIA_PAD_FL_MUST_CONNECT,
media_pipeline_start() will failed with -ENOLINK if it is not connected.

Thanks
Helen

> 
>> Actually I think that the code that set the 'active_sensor' (callingrkisp1_get_remote_sensor)
>> should move to here since this also check if the link to the sensor is enabled.
> 
> ok
> 
> Thanks for your review
> Helen
> 
>>
>> Thanks,
>> Dafna
>>
>>> -    rkisp1_stream_start(cap);
>>> -
>>> -    /* start sub-devices */
>>> -    ret = rkisp1_pipeline_sink_walk(entity, NULL,
>>> -                    rkisp1_pipeline_enable_cb);
>>> -    if (ret)
>>> -        goto err_stop_stream;
>>> -
>>>       ret = media_pipeline_start(entity, &cap->rkisp1->pipe);
>>>       if (ret) {
>>>           dev_err(cap->rkisp1->dev, "start pipeline failed %d\n", ret);
>>> -        goto err_pipe_disable;
>>> +        goto err_v4l2_pm_put;
>>>       }
>>> +    ret = rkisp1_pipeline_stream_enable(cap);
>>> +    if (ret)
>>> +        goto err_media_pipeline_stop;
>>>         mutex_unlock(&cap->rkisp1->stream_lock);
>>>         return 0;
>>>   -err_pipe_disable:
>>> -    rkisp1_pipeline_sink_walk(entity, NULL, rkisp1_pipeline_disable_cb);
>>> -err_stop_stream:
>>> -    rkisp1_stream_stop(cap);
>>> +err_media_pipeline_stop:
>>> +    media_pipeline_stop(entity);
>>> +err_v4l2_pm_put:
>>>       v4l2_pipeline_pm_put(entity);
>>>   err_pipe_pm_put:
>>>       pm_runtime_put(cap->rkisp1->dev);
>>>
>