Re: [PATCH v4 2/2] media: amphion: Add a frame flush mode for decoder

[Frank Li]

On Fri, Mar 28, 2025 at 02:48:17PM +0800, ming.qian@xxxxxxxxxxx wrote:
> From: Ming Qian <ming.qian@xxxxxxxxxxx>
>
> By default the amphion decoder will pre-parse 3 frames before starting
> to decode the first frame. Alternatively, a block of flush padding data
> can be appended to the frame, which will ensure that the decoder can
> start decoding immediately after parsing the flush padding data, thus
> potentially reducing decoding latency.
>
> This mode was previously only enabled, when the display delay was set to
> 0. Allow the user to manually toggle the use of that mode via a module
> parameter called low_latency, which enables the mode without
> changing the display order.
>
> Signed-off-by: Ming Qian <ming.qian@xxxxxxxxxxx>
> Reviewed-by: Nicolas Dufresne <nicolas.dufresne@xxxxxxxxxxxxx>
> ---
> v4
> - Improve the comment expressing
> v3
> - Improve commit message as recommended
> - Add some comments to avoid code looks cryptic
>
>  drivers/media/platform/amphion/vpu_malone.c | 14 +++++++++++++-
>  1 file changed, 13 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/media/platform/amphion/vpu_malone.c b/drivers/media/platform/amphion/vpu_malone.c
> index 88f8c16a451e..7f6251f7becb 100644
> --- a/drivers/media/platform/amphion/vpu_malone.c
> +++ b/drivers/media/platform/amphion/vpu_malone.c
> @@ -25,6 +25,10 @@
>  #include "vpu_imx8q.h"
>  #include "vpu_malone.h"
>
> +static bool low_latency;
> +module_param(low_latency, bool, 0644);
> +MODULE_PARM_DESC(low_latency, "Set low latency frame flush mode: 0 (disable) or 1 (enable)");
> +

If there are two malone instances, it will impact both instances, is it what
your expected? Prefer use sys interface to controller it.

Frank

>  #define CMD_SIZE			25600
>  #define MSG_SIZE			25600
>  #define CODEC_SIZE			0x1000
> @@ -1581,7 +1585,15 @@ static int vpu_malone_input_frame_data(struct vpu_malone_str_buffer __iomem *str
>
>  	vpu_malone_update_wptr(str_buf, wptr);
>
> -	if (disp_imm && !vpu_vb_is_codecconfig(vbuf)) {
> +	/*
> +	 * Enable the low latency flush mode if display delay is set to 0
> +	 * or the low latency frame flush mode if it is set to 1.
> +	 * The low latency flush mode requires some padding data to be appended to each frame,
> +	 * but there must not be any padding data between the sequence header and the frame.
> +	 * This module is currently only supported for the H264 and HEVC formats,
> +	 * for other formats, vpu_malone_add_scode() will return 0.
> +	 */
> +	if ((disp_imm || low_latency) && !vpu_vb_is_codecconfig(vbuf)) {
>  		ret = vpu_malone_add_scode(inst->core->iface,
>  					   inst->id,
>  					   &inst->stream_buffer,
> --
> 2.43.0-rc1
>