Re: [PATCH v3 2/2] media: amphion: Add a frame flush mode for decoder

[Sebastian Fricke]

Hey Ming,

On 05.03.2025 14:26, 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 frame_flush_mode, which enables the mode without
> changing the display order.
>
> Signed-off-by: Ming Qian <ming.qian@xxxxxxxxxxx>
> ---
> 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 1d9e10d9bec1..4ef9810d8142 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 frame_flush_mode;
> +module_param(frame_flush_mode, bool, 0644);
> +MODULE_PARM_DESC(frame_flush_mode, "Set low latency flush mode: 0 (disable) or 1 (enable)");
> +
> #define CMD_SIZE			25600
> #define MSG_SIZE			25600
> #define CODEC_SIZE			0x1000
> @@ -1579,7 +1583,15 @@ 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 parameter frame_flush_mode is set to 1.

s/or parameter frame_flush_mode is set to 1./
  or the frame flush mode if it is set to 1./

> +	 * The low latency flush mode requires some padding data to be appended after each frame,

s/appended after each/appended to each/
(the word append implies that something is added after something else)

> +	 * but don't put it in between the sequence header and frame.

s/but don't put it in between the sequence header and frame./
  but there must not be any padding data between the sequence header and the frame./

(As this is not a suggestion for the developer but a description of what
the code does)

> +	 * Only H264 and HEVC decoder support this module yet,

s/decoder/formats/

I'd rewrite this part:
This module is currently only supported for the H264 and HEVC formats,

but that is only because this sounds more natural to me.

> +	 * for other formats, vpu_malone_add_scode() will return 0.
> +	 */
> +	if ((disp_imm || frame_flush_mode) && !vpu_vb_is_codecconfig(vbuf)) {
> 		ret = vpu_malone_add_scode(inst->core->iface,
> 					   inst->id,
> 					   &inst->stream_buffer,
> --
> 2.43.0-rc1

Thank you!

Regards,
Sebastian Fricke