Re: [PATCH v6 07/18] media: vsp1: dl: Allow chained display lists for display pipelines

From: Kieran Bingham <kieran.bingham@ideasonboard.com>
To: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>,
	dri-devel@lists.freedesktop.org
Cc: linux-renesas-soc@vger.kernel.org,
	Liviu Dudau <Liviu.Dudau@arm.com>,
	linux-media@vger.kernel.org
Subject: Re: [PATCH v6 07/18] media: vsp1: dl: Allow chained display lists for display pipelines
Date: Wed, 13 Mar 2019 11:07:51 +0000	[thread overview]
Message-ID: <bae44783-9f9c-4908-796d-6ec1dbfcdca5@ideasonboard.com> (raw)
In-Reply-To: <20190313000532.7087-8-laurent.pinchart+renesas@ideasonboard.com>

Hi Laurent,

On 13/03/2019 00:05, Laurent Pinchart wrote:
> Refactor the display list header setup to allow chained display lists
> with display pipelines. Chain the display lists as for mem-to-mem
> pipelines, but enable the frame end interrupt for every list as display
> pipelines have a single list per frame.
> 
> This feature will be used to disable writeback exactly one frame after
> enabling it by chaining a writeback disable display list.
> 
> Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>

This is a bit hard to grok, but I can see that the key change is now
continuous display  pipelines can go into the code path which sets the
vsp1_dl_list *next. The rest of the refactoring looks good too.

Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>

> ---
>  drivers/media/platform/vsp1/vsp1_dl.c | 35 ++++++++++++++++++---------
>  1 file changed, 23 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/media/platform/vsp1/vsp1_dl.c b/drivers/media/platform/vsp1/vsp1_dl.c
> index 886b3a69d329..ed7cda4130f2 100644
> --- a/drivers/media/platform/vsp1/vsp1_dl.c
> +++ b/drivers/media/platform/vsp1/vsp1_dl.c
> @@ -770,17 +770,35 @@ static void vsp1_dl_list_fill_header(struct vsp1_dl_list *dl, bool is_last)
>  	}
>  
>  	dl->header->num_lists = num_lists;
> +	dl->header->flags = 0;
>  
> -	if (!list_empty(&dl->chain) && !is_last) {
> +	/*
> +	 * Enable the interrupt for the end of each frame. In continuous mode
> +	 * chained lists are used with one list per frame, so enable the
> +	 * interrupt for each list. In singleshot mode chained lists are used
> +	 * to partition a single frame, so enable the interrupt for the last
> +	 * list only.
> +	 */
> +	if (!dlm->singleshot || is_last)
> +		dl->header->flags |= VSP1_DLH_INT_ENABLE;
> +
> +	/*
> +	 * In continuous mode enable auto-start for all lists, as the VSP must
> +	 * loop on the same list until a new one is queued. In singleshot mode
> +	 * enable auto-start for all lists but the last to chain processing of
> +	 * partitions without software intervention.
> +	 */
> +	if (!dlm->singleshot || !is_last)
> +		dl->header->flags |= VSP1_DLH_AUTO_START;
> +
> +	if (!is_last) {
>  		/*
> -		 * If this display list's chain is not empty, we are on a list,
> -		 * and the next item is the display list that we must queue for
> -		 * automatic processing by the hardware.
> +		 * If this is not the last display list in the chain, queue the
> +		 * next item for automatic processing by the hardware.
>  		 */
>  		struct vsp1_dl_list *next = list_next_entry(dl, chain);
>  
>  		dl->header->next_header = next->dma;
> -		dl->header->flags = VSP1_DLH_AUTO_START;
>  	} else if (!dlm->singleshot) {
>  		/*
>  		 * if the display list manager works in continuous mode, the VSP
> @@ -788,13 +806,6 @@ static void vsp1_dl_list_fill_header(struct vsp1_dl_list *dl, bool is_last)
>  		 * instructed to do otherwise.
>  		 */
>  		dl->header->next_header = dl->dma;
> -		dl->header->flags = VSP1_DLH_INT_ENABLE | VSP1_DLH_AUTO_START;
> -	} else {
> -		/*
> -		 * Otherwise, in mem-to-mem mode, we work in single-shot mode
> -		 * and the next display list must not be started automatically.
> -		 */
> -		dl->header->flags = VSP1_DLH_INT_ENABLE;
>  	}
>  
>  	if (!dl->extension)
> 

-- 
Regards
--
Kieran
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