Re: [PATCH V1, 4/6] media: mtk-jpegdec: add jpeg decode worker interface

[AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>]

Il 03/12/21 06:34, kyrie.wu ha scritto:
> Add jpeg decoding worker to ensure that three HWs
> run in parallel in MT8195.
> 
> Signed-off-by: kyrie.wu <kyrie.wu@mediatek.com>
> ---
>   drivers/media/platform/mtk-jpeg/mtk_jpeg_core.c   | 190 +++++++++++++++++++---
>   drivers/media/platform/mtk-jpeg/mtk_jpeg_core.h   |   5 +
>   drivers/media/platform/mtk-jpeg/mtk_jpeg_dec_hw.c |  17 ++
>   3 files changed, 189 insertions(+), 23 deletions(-)
> 

Hello Kyrie,
thanks for the patch! However, there are some things to improve...

> diff --git a/drivers/media/platform/mtk-jpeg/mtk_jpeg_core.c b/drivers/media/platform/mtk-jpeg/mtk_jpeg_core.c
> index f2a5e84..2518660 100644
> --- a/drivers/media/platform/mtk-jpeg/mtk_jpeg_core.c
> +++ b/drivers/media/platform/mtk-jpeg/mtk_jpeg_core.c
> @@ -1065,57 +1065,187 @@ static void mtk_jpeg_enc_device_run(void *priv)
>   	queue_work(jpeg->workqueue, &ctx->jpeg_work);
>   }
>   
> -static void mtk_jpeg_dec_device_run(void *priv)
> +static int mtk_jpegdec_select_hw(struct mtk_jpeg_ctx *ctx)
>   {
> -	struct mtk_jpeg_ctx *ctx = priv;
> +	struct mtk_jpegdec_comp_dev *comp_jpeg;
>   	struct mtk_jpeg_dev *jpeg = ctx->jpeg;
> -	struct vb2_v4l2_buffer *src_buf, *dst_buf;
> -	enum vb2_buffer_state buf_state = VB2_BUF_STATE_ERROR;
>   	unsigned long flags;
> -	struct mtk_jpeg_src_buf *jpeg_src_buf;
> +	int hw_id = -1;
> +	int i;
> +
> +	spin_lock_irqsave(&jpeg->hw_lock, flags);
> +	for (i = 0; i < MTK_JPEGDEC_HW_MAX; i++) {
> +		comp_jpeg = jpeg->dec_hw_dev[i];
> +		if (comp_jpeg->hw_state == MTK_JPEG_HW_IDLE) {
> +			hw_id = i;
> +			comp_jpeg->hw_state = MTK_JPEG_HW_BUSY;
> +			break;
> +		}
> +	}
> +	spin_unlock_irqrestore(&jpeg->hw_lock, flags);
> +
> +	return hw_id;
> +}
> +
> +static int mtk_jpegdec_deselect_hw(struct mtk_jpeg_dev *jpeg, int hw_id)
> +{
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&jpeg->hw_lock, flags);
> +	jpeg->dec_hw_dev[hw_id]->hw_state =
> +		MTK_JPEG_HW_IDLE;
> +	spin_unlock_irqrestore(&jpeg->hw_lock, flags);
> +
> +	return 0;
> +}
> +
> +static int mtk_jpegdec_set_hw_param(struct mtk_jpeg_ctx *ctx,
> +	int hw_id,
> +	struct vb2_v4l2_buffer *src_buf,
> +	struct vb2_v4l2_buffer *dst_buf)
> +{
> +	struct mtk_jpegdec_comp_dev *jpeg =
> +		ctx->jpeg->dec_hw_dev[hw_id];
> +
> +	jpeg->hw_param.curr_ctx = ctx;
> +	jpeg->hw_param.src_buffer = src_buf;
> +	jpeg->hw_param.dst_buffer = dst_buf;
> +
> +	return 0;
> +}
> +
> +static void mtk_jpegdec_worker(struct work_struct *work)
> +{
> +	struct mtk_jpeg_ctx *ctx = container_of(work, struct mtk_jpeg_ctx,
> +		jpeg_work);
> +	struct mtk_jpegdec_comp_dev *comp_jpeg[MTK_JPEGDEC_HW_MAX];
> +	enum vb2_buffer_state buf_state = VB2_BUF_STATE_ERROR;
> +	struct mtk_jpeg_src_buf *jpeg_src_buf, *jpeg_dst_buf;
> +	struct vb2_v4l2_buffer *src_buf, *dst_buf;
> +	struct mtk_jpeg_dev *jpeg = ctx->jpeg;
> +	atomic_t *hw_rdy[MTK_JPEGDEC_HW_MAX];
> +	struct clk *jpegdec_clk;
> +	int ret, i, hw_id = 0;
>   	struct mtk_jpeg_bs bs;
>   	struct mtk_jpeg_fb fb;
> -	int ret;
> +	unsigned long flags;
> +
> +	for (i = 0; i < MTK_JPEGDEC_HW_MAX; i++) {
> +		comp_jpeg[i] = jpeg->dec_hw_dev[i];
> +		hw_rdy[i] = &comp_jpeg[i]->hw_rdy;
> +	}
> +

This entire retry_select block should go to a helper function instead
of being inside of here.

Also, there's a big issue with this snippet that has to be solved: you're
unconditionally calling "goto retry_select" at the end of the if branch,
but please consider the following scenario:

- mtk_jpegdec_select_hw() returns a hw_id < 0
- wait_event_interruptible returns 0
... then we redo the same, and we still get the same result.

This may generate an infinite loop!!

After putting this into a separate function, please use a controlled loop
with a well thought maximum number of retries, as to avoid this situation.

> +retry_select:
> +	hw_id = mtk_jpegdec_select_hw(ctx);
> +	if (hw_id < 0) {
> +		ret = wait_event_interruptible(jpeg->dec_hw_wq,
> +			(atomic_read(hw_rdy[0]) ||
> +			atomic_read(hw_rdy[1]) ||
> +			atomic_read(hw_rdy[2])) > 0);
> +		if (ret != 0) {
> +			dev_err(jpeg->dev, "%s : %d, all HW are busy\n",
> +				__func__, __LINE__);
> +			v4l2_m2m_job_finish(jpeg->m2m_dev, ctx->fh.m2m_ctx);
> +			return;
> +		}
> +
> +		dev_err(jpeg->dev, "%s : %d, NEW HW IDLE, please retry selcet!!!\n",
> +			__func__, __LINE__);
> +		goto retry_select;
> +	}
>   
> +	atomic_dec(&comp_jpeg[hw_id]->hw_rdy);
>   	src_buf = v4l2_m2m_next_src_buf(ctx->fh.m2m_ctx);
> +	if (!src_buf) {
> +		dev_err(jpeg->dev, "%s : %d, get src_buf fail !!!\n",
> +			__func__, __LINE__);
> +		goto getbuf_fail;
> +	}
>   	dst_buf = v4l2_m2m_next_dst_buf(ctx->fh.m2m_ctx);
> +	if (!dst_buf) {
> +		dev_err(jpeg->dev, "%s : %d, get dst_buf fail !!!\n",
> +			__func__, __LINE__);
> +		goto getbuf_fail;
> +	}
> +
>   	jpeg_src_buf = mtk_jpeg_vb2_to_srcbuf(&src_buf->vb2_buf);
> +	jpeg_dst_buf = mtk_jpeg_vb2_to_srcbuf(&dst_buf->vb2_buf);
>   
> -	if (mtk_jpeg_check_resolution_change(ctx, &jpeg_src_buf->dec_param)) {
> +	if (mtk_jpeg_check_resolution_change(ctx,
> +		&jpeg_src_buf->dec_param)) {

Why are you breaking this line? There's no need to.

>   		mtk_jpeg_queue_src_chg_event(ctx);
>   		ctx->state = MTK_JPEG_SOURCE_CHANGE;
> -		v4l2_m2m_job_finish(jpeg->m2m_dev, ctx->fh.m2m_ctx);
> -		return;
> +		goto getbuf_fail;
>   	}
>   


Regards,
- Angelo