Re: [PATCH] media: imx-jpeg: Add support for descriptor allocation from SRAM

[Frank Li <Frank.li@nxp.com>]

On Wed, Aug 20, 2025 at 06:29:53PM +0200, Marek Vasut wrote:
> Add support for optional allocation of bitstream descriptors from SRAM
> instead of DRAM. In case the encoder/decoder DT node contains 'sram'
> property which points to 'mmio-sram', the driver will attempt to use
> the SRAM instead of DRAM for descriptor allocation, which might improve
> performance.
>
> This however helps on i.MX95 with sporadic SLOTn_STATUS IMG_RD_ERR bit 11
> being triggered during JPEG encoding. The following pipeline triggers the
> problem when descriptors get allocated from DRAM, the pipeline often hangs
> after a few seconds and the encoder driver indicates "timeout, cancel it" :

Do you know why this happen if descriptor is in DRAM? why sram help this
case?

>
> gst-launch-1.0 videotestsrc ! video/x-raw,width=256,height=256,format=YUY2 ! \
>                queue ! v4l2jpegenc ! queue ! fakesink
>
> Signed-off-by: Marek Vasut <marek.vasut@mailbox.org>
> ---
...
> -							   GFP_ATOMIC);
> +	jpeg->slot_data.cfg_dec_vaddr = mxc_jpeg_alloc(jpeg, jpeg->slot_data.cfg_dec_size,
> +						       &jpeg->slot_data.cfg_dec_daddr);
>  	if (!jpeg->slot_data.cfg_dec_vaddr)
>  		goto err;
>
> @@ -2902,6 +2911,10 @@ static int mxc_jpeg_probe(struct platform_device *pdev)
>  	jpeg->dev = dev;
>  	jpeg->mode = mode;
>
> +	/* SRAM pool is optional */
> +	jpeg->sram_pool = of_gen_pool_get(pdev->dev.of_node, "sram", 0);

Need update binding doc nxp,imx8-jpeg.yaml

Frank

> +	dev_info(dev, "Using DMA descriptor pool in %cRAM\n", jpeg->sram_pool ? 'S' : 'D');
> +
>  	/* Get clocks */
>  	ret = devm_clk_bulk_get_all(&pdev->dev, &jpeg->clks);
>  	if (ret < 0) {
> diff --git a/drivers/media/platform/nxp/imx-jpeg/mxc-jpeg.h b/drivers/media/platform/nxp/imx-jpeg/mxc-jpeg.h
> index 7f0910fc9b47e..311f2f2ac519f 100644
> --- a/drivers/media/platform/nxp/imx-jpeg/mxc-jpeg.h
> +++ b/drivers/media/platform/nxp/imx-jpeg/mxc-jpeg.h
> @@ -142,6 +142,7 @@ struct mxc_jpeg_dev {
>  	int				num_domains;
>  	struct device			**pd_dev;
>  	struct device_link		**pd_link;
> +	struct gen_pool			*sram_pool;
>  };
>
>  /**
> --
> 2.50.1
>