Re: [PATCH v2 10/14] media: staging: rkisp1: isp: add a warning and debugfs var for irq delay

From: Helen Koike <helen.koike@collabora.com>
To: Dafna Hirschfeld <dafna.hirschfeld@collabora.com>,
	linux-media@vger.kernel.org
Cc: laurent.pinchart@ideasonboard.com, ezequiel@collabora.com,
	hverkuil@xs4all.nl, kernel@collabora.com, dafna3@gmail.com,
	sakari.ailus@linux.intel.com, linux-rockchip@lists.infradead.org,
	mchehab@kernel.org, tfiga@chromium.org
Subject: Re: [PATCH v2 10/14] media: staging: rkisp1: isp: add a warning and debugfs var for irq delay
Date: Mon, 17 Aug 2020 18:48:28 -0300	[thread overview]
Message-ID: <9a062761-84e0-d4e8-a909-53898562649a@collabora.com> (raw)
In-Reply-To: <20200815103734.31153-11-dafna.hirschfeld@collabora.com>

Hi Dafna,

On 8/15/20 7:37 AM, Dafna Hirschfeld wrote:
> The signal RKISP1_CIF_ISP_FRAME is set when the ISP completes
> outputting the frame to the next block in the pipeline.
> In order to keep buffer synchronization we assume that the
> RKISP1_CIF_ISP_V_START signal never arrives together with the
> RKISP1_CIF_ISP_FRAME signal.
> In case those signals arrive together then the code is not able to
> tell if the RKISP1_CIF_ISP_FRAME signal relates to the frame of
> the current v-start or the previous. This patch adds a WARN_ONCE
> and a debugfs var to catch it.
> 
> Signed-off-by: Dafna Hirschfeld <dafna.hirschfeld@collabora.com>
> ---
>  drivers/staging/media/rkisp1/rkisp1-common.h | 1 +
>  drivers/staging/media/rkisp1/rkisp1-dev.c    | 2 ++
>  drivers/staging/media/rkisp1/rkisp1-isp.c    | 5 +++++
>  3 files changed, 8 insertions(+)
> 
> diff --git a/drivers/staging/media/rkisp1/rkisp1-common.h b/drivers/staging/media/rkisp1/rkisp1-common.h
> index 79edece6ee77..5aed0e37850a 100644
> --- a/drivers/staging/media/rkisp1/rkisp1-common.h
> +++ b/drivers/staging/media/rkisp1/rkisp1-common.h
> @@ -228,6 +228,7 @@ struct rkisp1_debug {
>  	unsigned long outform_size_error;
>  	unsigned long img_stabilization_size_error;
>  	unsigned long inform_size_error;
> +	unsigned long irq_delay;
>  	unsigned long mipi_error;
>  	unsigned long stats_error;
>  	unsigned long stop_timeout[2];
> diff --git a/drivers/staging/media/rkisp1/rkisp1-dev.c b/drivers/staging/media/rkisp1/rkisp1-dev.c
> index a0eb8f08708b..557de940286b 100644
> --- a/drivers/staging/media/rkisp1/rkisp1-dev.c
> +++ b/drivers/staging/media/rkisp1/rkisp1-dev.c
> @@ -445,6 +445,8 @@ static void rkisp1_debug_init(struct rkisp1_device *rkisp1)
>  			     &debug->img_stabilization_size_error);
>  	debugfs_create_ulong("inform_size_error", 0444,  debug->debugfs_dir,
>  			     &debug->inform_size_error);
> +	debugfs_create_ulong("irq_delay", 0444,  debug->debugfs_dir,
> +			     &debug->irq_delay);
>  	debugfs_create_ulong("mipi_error", 0444, debug->debugfs_dir,
>  			     &debug->mipi_error);
>  	debugfs_create_ulong("stats_error", 0444, debug->debugfs_dir,
> diff --git a/drivers/staging/media/rkisp1/rkisp1-isp.c b/drivers/staging/media/rkisp1/rkisp1-isp.c
> index 1ffe7cc7bb12..33cfad19dde2 100644
> --- a/drivers/staging/media/rkisp1/rkisp1-isp.c
> +++ b/drivers/staging/media/rkisp1/rkisp1-isp.c
> @@ -1118,6 +1118,11 @@ void rkisp1_isp_isr(struct rkisp1_device *rkisp1)
>  		 */
>  		rkisp1->isp.frame_sequence++;
>  		rkisp1_isp_queue_event_sof(&rkisp1->isp);
> +		if (status & RKISP1_CIF_ISP_FRAME) {
> +			WARN_ONCE(1, "irq delay is too long, buffers might not be in sync\n");
> +			rkisp1->debug.irq_delay++;
> +		}
> +	}

I was wondering, if both interrupts arrive at the same time, shouldn't we handle the
frame before incrementing the frame_sequence?

I mean, move the code block

	if (status & RKISP1_CIF_ISP_V_START) {...}

after this other code block

	if (status & RKISP1_CIF_ISP_FRAME) {...}

Thanks,
Helen

>  
>  	if (status & RKISP1_CIF_ISP_PIC_SIZE_ERROR) {
>  		/* Clear pic_size_error */
> 