linux-kernel - Re: [PATCH 3/3] media: imx-jpeg: Check decoding is ongoing for motion-jpeg

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Message-ID: <Z+Vjh8Iywt1o9+IS@lizhi-Precision-Tower-5810>
Date: Thu, 27 Mar 2025 10:41:11 -0400
From: Frank Li <Frank.li@....com>
To: ming.qian@....nxp.com
Cc: mchehab@...nel.org, hverkuil-cisco@...all.nl,
	mirela.rabulea@....nxp.com, shawnguo@...nel.org,
	s.hauer@...gutronix.de, kernel@...gutronix.de, festevam@...il.com,
	xiahong.bao@....com, eagle.zhou@....com, linux-imx@....com,
	imx@...ts.linux.dev, linux-media@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 3/3] media: imx-jpeg: Check decoding is ongoing for
 motion-jpeg

On Thu, Mar 27, 2025 at 10:37:07AM +0800, ming.qian@....nxp.com wrote:
> From: Ming Qian <ming.qian@....nxp.com>
>
> To support decoding motion-jpeg without DHT, driver will try to decode a
> pattern jpeg before actual jpeg frame by use of linked descriptors
> (This is called "repeat mode"), then the DHT in the pattern jpeg can be
> used for decoding the motion-jpeg.
>
> In other words, 2 frame done interrupts will be triggered, driver will
> ignore the first interrupt, and wait for the second interrupt.
> If the resolution is small, and the 2 interrupts may be too close,
> when driver is handling the first interrupt, two frames are done, then
> driver will fail to wait for the second interrupt.
>
> In such case, driver can check whether the decoding is still ongoing,
> if not, just done the current decoding.
>
> Signed-off-by: Ming Qian <ming.qian@....nxp.com>
> ---
>  .../media/platform/nxp/imx-jpeg/mxc-jpeg-hw.h |  1 +
>  .../media/platform/nxp/imx-jpeg/mxc-jpeg.c    | 20 ++++++++++++++++++-
>  2 files changed, 20 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/media/platform/nxp/imx-jpeg/mxc-jpeg-hw.h b/drivers/media/platform/nxp/imx-jpeg/mxc-jpeg-hw.h
> index d579c804b047..adb93e977be9 100644
> --- a/drivers/media/platform/nxp/imx-jpeg/mxc-jpeg-hw.h
> +++ b/drivers/media/platform/nxp/imx-jpeg/mxc-jpeg-hw.h
> @@ -89,6 +89,7 @@
>  /* SLOT_STATUS fields for slots 0..3 */
>  #define SLOT_STATUS_FRMDONE			(0x1 << 3)
>  #define SLOT_STATUS_ENC_CONFIG_ERR		(0x1 << 8)
> +#define SLOT_STATUS_ONGOING			(0x1 << 31)
>
>  /* SLOT_IRQ_EN fields TBD */
>
> diff --git a/drivers/media/platform/nxp/imx-jpeg/mxc-jpeg.c b/drivers/media/platform/nxp/imx-jpeg/mxc-jpeg.c
> index 45705c606769..e6bb45633a19 100644
> --- a/drivers/media/platform/nxp/imx-jpeg/mxc-jpeg.c
> +++ b/drivers/media/platform/nxp/imx-jpeg/mxc-jpeg.c
> @@ -910,6 +910,23 @@ static u32 mxc_jpeg_get_plane_size(struct mxc_jpeg_q_data *q_data, u32 plane_no)
>  	return size;
>  }
>
> +static bool mxc_dec_is_ongoing(struct mxc_jpeg_ctx *ctx)
> +{
> +	struct mxc_jpeg_dev *jpeg = ctx->mxc_jpeg;
> +	u32 curr_desc;
> +	u32 slot_status;
> +
> +	slot_status = readl(jpeg->base_reg + MXC_SLOT_OFFSET(ctx->slot, SLOT_STATUS));
> +	curr_desc = readl(jpeg->base_reg + MXC_SLOT_OFFSET(ctx->slot, SLOT_CUR_DESCPT_PTR));
> +
> +	if (curr_desc == jpeg->slot_data.cfg_desc_handle)
> +		return true;
> +	if (slot_status & SLOT_STATUS_ONGOING)
> +		return true;
> +
> +	return false;
> +}
> +
>  static irqreturn_t mxc_jpeg_dec_irq(int irq, void *priv)
>  {
>  	struct mxc_jpeg_dev *jpeg = priv;
> @@ -979,7 +996,8 @@ static irqreturn_t mxc_jpeg_dec_irq(int irq, void *priv)
>  		mxc_jpeg_enc_mode_go(dev, reg, mxc_jpeg_is_extended_sequential(q_data->fmt));
>  		goto job_unlock;
>  	}
> -	if (jpeg->mode == MXC_JPEG_DECODE && jpeg_src_buf->dht_needed) {
> +	if (jpeg->mode == MXC_JPEG_DECODE && jpeg_src_buf->dht_needed &&
> +	    mxc_dec_is_ongoing(ctx)) {

what happen if hardware completed just after you call mxc_dec_is_ongoing(),
any thing will be missed?

Frank

>  		jpeg_src_buf->dht_needed = false;
>  		dev_dbg(dev, "Decoder DHT cfg finished. Start decoding...\n");
>  		goto job_unlock;
> --
> 2.43.0-rc1
>