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Message-ID: <8cc69501-40a4-c6ba-e526-9abd2d938acb@xs4all.nl>
Date: Mon, 26 Feb 2018 14:56:45 +0100
From: Hans Verkuil <hverkuil@...all.nl>
To: Hugues Fruchet <hugues.fruchet@...com>,
Maxime Coquelin <mcoquelin.stm32@...il.com>,
Alexandre Torgue <alexandre.torgue@...com>,
Mauro Carvalho Chehab <mchehab@...nel.org>
Cc: linux-media@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
linux-kernel@...r.kernel.org,
Benjamin Gaignard <benjamin.gaignard@...aro.org>,
Yannick Fertre <yannick.fertre@...com>
Subject: Re: [PATCH v2] media: stm32-dcmi: fix lock scheme
On 02/22/2018 10:49 AM, Hugues Fruchet wrote:
> Fix lock scheme leading to spurious freeze.
Can you elaborate a bit more? It's hard to review since you don't
describe what was wrong and why this fixes the problem.
Regards,
Hans
>
> Signed-off-by: Hugues Fruchet <hugues.fruchet@...com>
> ---
> version 2:
> - dcmi_buf_queue() refactor to avoid to have "else" after "return"
> (warning detected by checkpatch.pl --strict -f stm32-dcmi.c)
>
> drivers/media/platform/stm32/stm32-dcmi.c | 57 +++++++++++++------------------
> 1 file changed, 24 insertions(+), 33 deletions(-)
>
> diff --git a/drivers/media/platform/stm32/stm32-dcmi.c b/drivers/media/platform/stm32/stm32-dcmi.c
> index 2fd8bed..5de18ad 100644
> --- a/drivers/media/platform/stm32/stm32-dcmi.c
> +++ b/drivers/media/platform/stm32/stm32-dcmi.c
> @@ -197,7 +197,7 @@ static void dcmi_dma_callback(void *param)
> struct dma_tx_state state;
> enum dma_status status;
>
> - spin_lock(&dcmi->irqlock);
> + spin_lock_irq(&dcmi->irqlock);
>
> /* Check DMA status */
> status = dmaengine_tx_status(chan, dcmi->dma_cookie, &state);
> @@ -239,7 +239,7 @@ static void dcmi_dma_callback(void *param)
> dcmi->errors_count++;
> dcmi->active = NULL;
>
> - spin_unlock(&dcmi->irqlock);
> + spin_unlock_irq(&dcmi->irqlock);
> return;
> }
>
> @@ -248,13 +248,11 @@ static void dcmi_dma_callback(void *param)
>
> list_del_init(&dcmi->active->list);
>
> - if (dcmi_start_capture(dcmi)) {
> + spin_unlock_irq(&dcmi->irqlock);
> + if (dcmi_start_capture(dcmi))
> dev_err(dcmi->dev, "%s: Cannot restart capture on DMA complete\n",
> __func__);
> -
> - spin_unlock(&dcmi->irqlock);
> - return;
> - }
> + return;
> }
>
> break;
> @@ -263,7 +261,7 @@ static void dcmi_dma_callback(void *param)
> break;
> }
>
> - spin_unlock(&dcmi->irqlock);
> + spin_unlock_irq(&dcmi->irqlock);
> }
>
> static int dcmi_start_dma(struct stm32_dcmi *dcmi,
> @@ -360,7 +358,7 @@ static irqreturn_t dcmi_irq_thread(int irq, void *arg)
> {
> struct stm32_dcmi *dcmi = arg;
>
> - spin_lock(&dcmi->irqlock);
> + spin_lock_irq(&dcmi->irqlock);
>
> /* Stop capture is required */
> if (dcmi->state == STOPPING) {
> @@ -370,7 +368,7 @@ static irqreturn_t dcmi_irq_thread(int irq, void *arg)
>
> complete(&dcmi->complete);
>
> - spin_unlock(&dcmi->irqlock);
> + spin_unlock_irq(&dcmi->irqlock);
> return IRQ_HANDLED;
> }
>
> @@ -383,35 +381,34 @@ static irqreturn_t dcmi_irq_thread(int irq, void *arg)
> __func__);
>
> dcmi->errors_count++;
> - dmaengine_terminate_all(dcmi->dma_chan);
> -
> dev_dbg(dcmi->dev, "Restarting capture after DCMI error\n");
>
> - if (dcmi_start_capture(dcmi)) {
> + spin_unlock_irq(&dcmi->irqlock);
> + dmaengine_terminate_all(dcmi->dma_chan);
> +
> + if (dcmi_start_capture(dcmi))
> dev_err(dcmi->dev, "%s: Cannot restart capture on overflow or error\n",
> __func__);
> -
> - spin_unlock(&dcmi->irqlock);
> - return IRQ_HANDLED;
> - }
> + return IRQ_HANDLED;
> }
>
> - spin_unlock(&dcmi->irqlock);
> + spin_unlock_irq(&dcmi->irqlock);
> return IRQ_HANDLED;
> }
>
> static irqreturn_t dcmi_irq_callback(int irq, void *arg)
> {
> struct stm32_dcmi *dcmi = arg;
> + unsigned long flags;
>
> - spin_lock(&dcmi->irqlock);
> + spin_lock_irqsave(&dcmi->irqlock, flags);
>
> dcmi->misr = reg_read(dcmi->regs, DCMI_MIS);
>
> /* Clear interrupt */
> reg_set(dcmi->regs, DCMI_ICR, IT_FRAME | IT_OVR | IT_ERR);
>
> - spin_unlock(&dcmi->irqlock);
> + spin_unlock_irqrestore(&dcmi->irqlock, flags);
>
> return IRQ_WAKE_THREAD;
> }
> @@ -490,9 +487,8 @@ static void dcmi_buf_queue(struct vb2_buffer *vb)
> struct stm32_dcmi *dcmi = vb2_get_drv_priv(vb->vb2_queue);
> struct vb2_v4l2_buffer *vbuf = to_vb2_v4l2_buffer(vb);
> struct dcmi_buf *buf = container_of(vbuf, struct dcmi_buf, vb);
> - unsigned long flags = 0;
>
> - spin_lock_irqsave(&dcmi->irqlock, flags);
> + spin_lock_irq(&dcmi->irqlock);
>
> if ((dcmi->state == RUNNING) && (!dcmi->active)) {
> dcmi->active = buf;
> @@ -500,19 +496,15 @@ static void dcmi_buf_queue(struct vb2_buffer *vb)
> dev_dbg(dcmi->dev, "Starting capture on buffer[%d] queued\n",
> buf->vb.vb2_buf.index);
>
> - if (dcmi_start_capture(dcmi)) {
> + spin_unlock_irq(&dcmi->irqlock);
> + if (dcmi_start_capture(dcmi))
> dev_err(dcmi->dev, "%s: Cannot restart capture on overflow or error\n",
> __func__);
> -
> - spin_unlock_irqrestore(&dcmi->irqlock, flags);
> - return;
> - }
> } else {
> /* Enqueue to video buffers list */
> list_add_tail(&buf->list, &dcmi->buffers);
> + spin_unlock_irq(&dcmi->irqlock);
> }
> -
> - spin_unlock_irqrestore(&dcmi->irqlock, flags);
> }
>
> static int dcmi_start_streaming(struct vb2_queue *vq, unsigned int count)
> @@ -598,20 +590,17 @@ static int dcmi_start_streaming(struct vb2_queue *vq, unsigned int count)
>
> dev_dbg(dcmi->dev, "Start streaming, starting capture\n");
>
> + spin_unlock_irq(&dcmi->irqlock);
> ret = dcmi_start_capture(dcmi);
> if (ret) {
> dev_err(dcmi->dev, "%s: Start streaming failed, cannot start capture\n",
> __func__);
> -
> - spin_unlock_irq(&dcmi->irqlock);
> goto err_subdev_streamoff;
> }
>
> /* Enable interruptions */
> reg_set(dcmi->regs, DCMI_IER, IT_FRAME | IT_OVR | IT_ERR);
>
> - spin_unlock_irq(&dcmi->irqlock);
> -
> return 0;
>
> err_subdev_streamoff:
> @@ -654,7 +643,9 @@ static void dcmi_stop_streaming(struct vb2_queue *vq)
> dev_err(dcmi->dev, "%s: Failed to stop streaming, subdev streamoff error (%d)\n",
> __func__, ret);
>
> + spin_lock_irq(&dcmi->irqlock);
> dcmi->state = STOPPING;
> + spin_unlock_irq(&dcmi->irqlock);
>
> timeout = wait_for_completion_interruptible_timeout(&dcmi->complete,
> time_ms);
>
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