On 24/05/2023 18:36, Vikash Garodia wrote:
>
> On 5/24/2023 8:14 PM, Hans Verkuil wrote:
>> On 24/05/2023 16:29, Bryan O'Donoghue wrote:
>>> On 24/05/2023 15:12, Sergey Senozhatsky wrote:
>>>> Video device has to provide ->lock so that __video_do_ioctl()
>>>> can serialize IOCTL calls. Provided dedicated enc/dec mutex-s
>>>> for that purpose.
> Why do we need to serialize at device context ? Please share some details on the
> issue faced leading to the serialization. This may impact performance, let say,
> when we have multiple concurrent video sessions running at the same time and the
> ioctl for one session have to wait if the lock is taken by another session ioctl.
>
>>>>
>>>> Signed-off-by: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx>
>>
>> Since these are m2m devices, I think this should set vfh->m2m_ctx->q_lock
>> instead.
>>
>> The vb2_queue is per filehandle for such devices, so by just setting
>> vdev->lock you will have all vb2_queues use the same mutex.
>>
>> Instead the struct v4l2_m2m_ctx q_lock pointer, if set, will use that
>> mutex for all vb2 operations.
>>
>> I think you can set it to the 'lock' mutex in struct venus_inst.
>
> IIUC, the suggestion is to use the 'lock' in struct venus_inst while
> initializing the queue. This might lead to deadlock as the same lock is used
> during vb2 operations in driver. Might be introducing a new lock for this
> purpose in struct venus_inst would do, unless we are trying to serialize at
> video device (or core) context.
For the record, I have not analyzed how that lock is used in the driver,
so if a new mutex has to be added to venus_inst rather than reusing the
existing one, then that's fine by me.
But it should be a instance-specific mutex, not one at the device level.
Regards,
Hans
>
>>
>> Regards,
>>
>> Hans
>>
>>>> ---
>>>> drivers/media/platform/qcom/venus/core.h | 4 ++++
>>>> drivers/media/platform/qcom/venus/vdec.c | 2 ++
>>>> drivers/media/platform/qcom/venus/venc.c | 2 ++
>>>> 3 files changed, 8 insertions(+)
>>>>
>>>> diff --git a/drivers/media/platform/qcom/venus/core.h b/drivers/media/platform/qcom/venus/core.h
>>>> index 4f81669986ba..b6c9a653a007 100644
>>>> --- a/drivers/media/platform/qcom/venus/core.h
>>>> +++ b/drivers/media/platform/qcom/venus/core.h
>>>> @@ -113,7 +113,9 @@ struct venus_format {
>>>> * @opp_pmdomain: an OPP power-domain
>>>> * @resets: an array of reset signals
>>>> * @vdev_dec: a reference to video device structure for decoder instances
>>>> + * @vdev_dec_lock: decoder instance video device ioctl lock
>>>> * @vdev_enc: a reference to video device structure for encoder instances
>>>> + * @vdev_enc_lock: encoder instance video device ioctl lock
>>>> * @v4l2_dev: a holder for v4l2 device structure
>>>> * @res: a reference to venus resources structure
>>>> * @dev: convenience struct device pointer
>>>> @@ -165,7 +167,9 @@ struct venus_core {
>>>> struct device *opp_pmdomain;
>>>> struct reset_control *resets[VIDC_RESETS_NUM_MAX];
>>>> struct video_device *vdev_dec;
>>>> + struct mutex vdev_dec_lock;
>>>> struct video_device *vdev_enc;
>>>> + struct mutex vdev_enc_lock;
>>>> struct v4l2_device v4l2_dev;
>>>> const struct venus_resources *res;
>>>> struct device *dev;
>>>> diff --git a/drivers/media/platform/qcom/venus/vdec.c b/drivers/media/platform/qcom/venus/vdec.c
>>>> index 51a53bf82bd3..7e9363714bfb 100644
>>>> --- a/drivers/media/platform/qcom/venus/vdec.c
>>>> +++ b/drivers/media/platform/qcom/venus/vdec.c
>>>> @@ -1760,6 +1760,7 @@ static int vdec_probe(struct platform_device *pdev)
>>>> if (!vdev)
>>>> return -ENOMEM;
>>>> + mutex_init(&core->vdev_dec_lock);
>>>> strscpy(vdev->name, "qcom-venus-decoder", sizeof(vdev->name));
>>>> vdev->release = video_device_release;
>>>> vdev->fops = &vdec_fops;
>>>> @@ -1767,6 +1768,7 @@ static int vdec_probe(struct platform_device *pdev)
>>>> vdev->vfl_dir = VFL_DIR_M2M;
>>>> vdev->v4l2_dev = &core->v4l2_dev;
>>>> vdev->device_caps = V4L2_CAP_VIDEO_M2M_MPLANE | V4L2_CAP_STREAMING;
>>>> + vdev->lock = &core->vdev_dec_lock;
>>>> ret = video_register_device(vdev, VFL_TYPE_VIDEO, -1);
>>>> if (ret)
>>>> diff --git a/drivers/media/platform/qcom/venus/venc.c b/drivers/media/platform/qcom/venus/venc.c
>>>> index 4666f42feea3..8522ed339d5d 100644
>>>> --- a/drivers/media/platform/qcom/venus/venc.c
>>>> +++ b/drivers/media/platform/qcom/venus/venc.c
>>>> @@ -1558,6 +1558,7 @@ static int venc_probe(struct platform_device *pdev)
>>>> if (!vdev)
>>>> return -ENOMEM;
>>>> + mutex_init(&core->vdev_enc_lock);
>>>> strscpy(vdev->name, "qcom-venus-encoder", sizeof(vdev->name));
>>>> vdev->release = video_device_release;
>>>> vdev->fops = &venc_fops;
>>>> @@ -1565,6 +1566,7 @@ static int venc_probe(struct platform_device *pdev)
>>>> vdev->vfl_dir = VFL_DIR_M2M;
>>>> vdev->v4l2_dev = &core->v4l2_dev;
>>>> vdev->device_caps = V4L2_CAP_VIDEO_M2M_MPLANE | V4L2_CAP_STREAMING;
>>>> + vdev->lock = &core->vdev_enc_lock;
>>>> ret = video_register_device(vdev, VFL_TYPE_VIDEO, -1);
>>>> if (ret)
>>>
>>> LGTM
>>>
>>> Reviewed-by: Bryan O'Donoghue <bryan.odonoghue@xxxxxxxxxx>
>>
