Re: [PATCH v2 3/3] media: imx-jpeg: Check decoding is ongoing for motion-jpeg

Frank Li
2025-03-28T14:45:57Z

On Fri, Mar 28, 2025 at 02:30:52PM +0800, ming.qian@oss.nxp.com wrote:
> From: Ming Qian <ming.qian@oss.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,

Does any field in linked descriptors to control if issue irq? Generally
you needn't enable first descriptors's irq and only enable second one.

> and wait for the second interrupt.
> If the resolution is small, and the 2 interrupts may be too close,

It also possible two irqs combine to 1 irqs. If I understand correct, your
irq handle only handle one descriptors per irq.

Another words,

If second irq already happen just before 1,

1. dec_ret = readl(reg + MXC_SLOT_OFFSET(slot, SLOT_STATUS));
2. writel(dec_ret, reg + MXC_SLOT_OFFSET(slot, SLOT_STATUS)); /* w1c */

Does your driver wait forever because no second irq happen?

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