linux-kernel - Re: [PATCH 3/6] media: vsp1: Implement partition algorithm restrictions

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Message-ID: <2105926.aDGgcdDEj3@avalon>
Date:   Fri, 14 Sep 2018 13:38:00 +0300
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Kieran Bingham <kieran.bingham+renesas@...asonboard.com>
Cc:     mchehab@...nel.org, linux-media@...r.kernel.org,
        linux-renesas-soc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/6] media: vsp1: Implement partition algorithm restrictions

Hi Kieran,

Thank you for the patch.

On Friday, 31 August 2018 17:40:41 EEST Kieran Bingham wrote:
> The partition algorithm introduced to support scaling, and rotation on

s/,//

> Gen3 hardware has some restrictions on pipeline configuration.
> 
> The UDS must not be connected after the SRU in a pipeline, and whilst an
> SRU can be connected after the UDS, it can only do so in identity mode.
> 
> A pipeline with an SRU connected after the UDS will disable any scaling
> features of the SRU.
> 
> Signed-off-by: Kieran Bingham <kieran.bingham+renesas@...asonboard.com>
> ---
>  drivers/media/platform/vsp1/vsp1_sru.c   |  7 ++++--
>  drivers/media/platform/vsp1/vsp1_sru.h   |  1 +
>  drivers/media/platform/vsp1/vsp1_video.c | 29 +++++++++++++++++++++++-
>  3 files changed, 34 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/media/platform/vsp1/vsp1_sru.c
> b/drivers/media/platform/vsp1/vsp1_sru.c index 04e4e05af6ae..f277700e5cc2
> 100644
> --- a/drivers/media/platform/vsp1/vsp1_sru.c
> +++ b/drivers/media/platform/vsp1/vsp1_sru.c
> @@ -149,7 +149,8 @@ static int sru_enum_frame_size(struct v4l2_subdev
> *subdev, fse->min_width = format->width;
>  		fse->min_height = format->height;
>  		if (format->width <= SRU_MAX_SIZE / 2 &&
> -		    format->height <= SRU_MAX_SIZE / 2) {
> +		    format->height <= SRU_MAX_SIZE / 2 &&
> +		    sru->force_identity_mode == false) {
>  			fse->max_width = format->width * 2;
>  			fse->max_height = format->height * 2;
>  		} else {
> @@ -201,7 +202,8 @@ static void sru_try_format(struct vsp1_sru *sru,
> 
>  		if (fmt->width <= SRU_MAX_SIZE / 2 &&
>  		    fmt->height <= SRU_MAX_SIZE / 2 &&
> -		    output_area > input_area * 9 / 4) {
> +		    output_area > input_area * 9 / 4 &&
> +		    sru->force_identity_mode == false) {
>  			fmt->width = format->width * 2;
>  			fmt->height = format->height * 2;
>  		} else {

What if the format is configured first while the SRU isn't connected after a 
UDS, the pipeline then reconfigured to add the UDS, and streaming started ? 
Furthermore the force_identity_mode flag will only be set at streamon time, as 
that's when vsp1_video_pipeline_build_branch() is called.

> @@ -374,6 +376,7 @@ struct vsp1_sru *vsp1_sru_create(struct vsp1_device
> *vsp1) v4l2_ctrl_new_custom(&sru->ctrls, &sru_intensity_control, NULL);
> 
>  	sru->intensity = 1;
> +	sru->force_identity_mode = false;

This is not needed as the whole structure is initialized to 0, but it doesn't 
hurt too much either.

>  	sru->entity.subdev.ctrl_handler = &sru->ctrls;
> 
> diff --git a/drivers/media/platform/vsp1/vsp1_sru.h
> b/drivers/media/platform/vsp1/vsp1_sru.h index ddb00eadd1ea..28da98d86366
> 100644
> --- a/drivers/media/platform/vsp1/vsp1_sru.h
> +++ b/drivers/media/platform/vsp1/vsp1_sru.h
> @@ -26,6 +26,7 @@ struct vsp1_sru {
>  	struct v4l2_ctrl_handler ctrls;
> 
>  	unsigned int intensity;
> +	bool force_identity_mode;
>  };

While at it, could you add kerneldoc for the structure ?

>  static inline struct vsp1_sru *to_sru(struct v4l2_subdev *subdev)
> diff --git a/drivers/media/platform/vsp1/vsp1_video.c
> b/drivers/media/platform/vsp1/vsp1_video.c index e78eadd0295b..9404d7968371
> 100644
> --- a/drivers/media/platform/vsp1/vsp1_video.c
> +++ b/drivers/media/platform/vsp1/vsp1_video.c
> @@ -31,6 +31,7 @@
>  #include "vsp1_hgt.h"
>  #include "vsp1_pipe.h"
>  #include "vsp1_rwpf.h"
> +#include "vsp1_sru.h"
>  #include "vsp1_uds.h"
>  #include "vsp1_video.h"
> 
> @@ -480,10 +481,12 @@ static int vsp1_video_pipeline_build_branch(struct
> vsp1_pipeline *pipe, struct vsp1_rwpf *input,
>  					    struct vsp1_rwpf *output)
>  {
> +	struct vsp1_device *vsp1 = output->entity.vsp1;
>  	struct media_entity_enum ent_enum;
>  	struct vsp1_entity *entity;
>  	struct media_pad *pad;
>  	struct vsp1_brx *brx = NULL;
> +	bool sru_found = false;
>  	int ret;
> 
>  	ret = media_entity_enum_init(&ent_enum, &input->entity.vsp1->media_dev);
> @@ -540,13 +543,37 @@ static int vsp1_video_pipeline_build_branch(struct
> vsp1_pipeline *pipe, goto out;
>  		}
> 
> -		/* UDS can't be chained. */
> +		if (entity->type == VSP1_ENTITY_SRU) {
> +			struct vsp1_sru *sru = to_sru(&entity->subdev);
> +
> +			/*
> +			 * Gen3 partition algorithm restricts SRU double-scaled
> +			 * resolution if it is connected after a UDS entity.
> +			 */
> +			if (vsp1->info->gen == 3 && pipe->uds)
> +				sru->force_identity_mode = true;

The flag is never reset to false.

Seems you're missing at least two unit tests for this patch :-)

> +
> +			sru_found = true;
> +		}
> +
>  		if (entity->type == VSP1_ENTITY_UDS) {
> +			/* UDS can't be chained. */
>  			if (pipe->uds) {
>  				ret = -EPIPE;
>  				goto out;
>  			}
> 
> +			/*
> +			 * On Gen3 hardware using the partition algorithm, the
> +			 * UDS must not be connected after the SRU. Using the
> +			 * SRU on Gen3 will always engage the partition
> +			 * algorithm.
> +			 */
> +			if (vsp1->info->gen == 3 && sru_found) {
> +				ret = -EPIPE;
> +				goto out;
> +			}
> +
>  			pipe->uds = entity;
>  			pipe->uds_input = brx ? &brx->entity : &input->entity;
>  		}

-- 
Regards,

Laurent Pinchart