linux-kernel - Re: [PATCH v2 4/7] media: chips-media: wave5: Use spinlock whenever statue is changed

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Message-ID: <effe40f0d4caef43bf772d350a67d68833941cbb.camel@collabora.com>
Date: Fri, 23 May 2025 13:41:18 -0400
From: Nicolas Dufresne <nicolas.dufresne@...labora.com>
To: "Jackson.lee" <jackson.lee@...psnmedia.com>, mchehab@...nel.org, 
	hverkuil-cisco@...all.nl, sebastian.fricke@...labora.com, 
	bob.beckett@...labora.com, dafna.hirschfeld@...labora.com
Cc: linux-media@...r.kernel.org, linux-kernel@...r.kernel.org, 
	lafley.kim@...psnmedia.com, b-brnich@...com, hverkuil@...all.nl, 
	nas.chung@...psnmedia.com
Subject: Re: [PATCH v2 4/7] media: chips-media: wave5: Use spinlock whenever
 statue is changed

Hi,

Le jeudi 22 mai 2025 à 16:26 +0900, Jackson.lee a écrit :
> From: Jackson Lee <jackson.lee@...psnmedia.com>
> 
> The device_run and finish_decode is not any more synchronized,
> so lock was needed in the device_run whenever state was changed.

Can you try to introduce the locking ahead of the patches, otherwise
this break bisectability as the in-between become racy.

Nicolas

> 
> Signed-off-by: Jackson Lee <jackson.lee@...psnmedia.com>
> Signed-off-by: Nas Chung <nas.chung@...psnmedia.com>
> ---
>  drivers/media/platform/chips-media/wave5/wave5-vpu-dec.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/media/platform/chips-media/wave5/wave5-vpu-dec.c b/drivers/media/platform/chips-
> media/wave5/wave5-vpu-dec.c
> index 42981c3b49bc..719c5527eb7f 100644
> --- a/drivers/media/platform/chips-media/wave5/wave5-vpu-dec.c
> +++ b/drivers/media/platform/chips-media/wave5/wave5-vpu-dec.c
> @@ -1577,6 +1577,7 @@ static void wave5_vpu_dec_device_run(void *priv)
>  	struct queue_status_info q_status;
>  	u32 fail_res = 0;
>  	int ret = 0;
> +	unsigned long flags;
>  
>  	dev_dbg(inst->dev->dev, "%s: Fill the ring buffer with new bitstream data", __func__);
>  	pm_runtime_resume_and_get(inst->dev->dev);
> @@ -1617,7 +1618,9 @@ static void wave5_vpu_dec_device_run(void *priv)
>  			}
>  			spin_unlock_irqrestore(&inst->state_spinlock, flags);
>  		} else {
> +			spin_lock_irqsave(&inst->state_spinlock, flags);
>  			switch_state(inst, VPU_INST_STATE_INIT_SEQ);
> +			spin_unlock_irqrestore(&inst->state_spinlock, flags);
>  		}
>  
>  		break;
> @@ -1628,8 +1631,9 @@ static void wave5_vpu_dec_device_run(void *priv)
>  		 * we had a chance to switch, which leads to an invalid state
>  		 * change.
>  		 */
> +		spin_lock_irqsave(&inst->state_spinlock, flags);
>  		switch_state(inst, VPU_INST_STATE_PIC_RUN);
> -
> +		spin_unlock_irqrestore(&inst->state_spinlock, flags);
>  		/*
>  		 * During DRC, the picture decoding remains pending, so just leave the job
>  		 * active until this decode operation completes.
> @@ -1643,7 +1647,9 @@ static void wave5_vpu_dec_device_run(void *priv)
>  		ret = wave5_prepare_fb(inst);
>  		if (ret) {
>  			dev_warn(inst->dev->dev, "Framebuffer preparation, fail: %d\n", ret);
> +			spin_lock_irqsave(&inst->state_spinlock, flags);
>  			switch_state(inst, VPU_INST_STATE_STOP);
> +			spin_unlock_irqrestore(&inst->state_spinlock, flags);
>  			break;
>  		}
>