linux-kernel - Re: [PATCH v2 12/18] media: i2c: rdacm21: Give more time to OV490 to boot

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Date:   Mon, 15 Mar 2021 17:22:37 +0000
From:   Kieran Bingham <kieran.bingham+renesas@...asonboard.com>
To:     Jacopo Mondi <jacopo+renesas@...ndi.org>,
        laurent.pinchart+renesas@...asonboard.com,
        niklas.soderlund+renesas@...natech.se, geert@...ux-m68k.org
Cc:     Mauro Carvalho Chehab <mchehab@...nel.org>,
        linux-media@...r.kernel.org, linux-renesas-soc@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 12/18] media: i2c: rdacm21: Give more time to OV490 to
 boot

On 15/03/2021 13:15, Jacopo Mondi wrote:
> It has been observed through repeated testing (250 boots) that in the
> 10% of the cases the RDACM21 initialization sequence errors out due a
> timeout waiting for the OV490 firmware to complete its boot phase.
> 
> Albeit being the current timeout relatively large (300-600 milliseconds),
> doubling it reduces the sporadic error rate down to 1 over an 80 boot
> sequences test run.
> 
> The firmware boot delay is unfortunately not characterized in the camera
> module manual.
> 

I wonder if we could characterize this alone by pulling this down until
we see failures increase, with all the other fixes in place...

I don't think that's required, but it might be something to check later
if we don't get rid of that 1/80 failure.



> Fixes: a59f853b3b4b ("media: i2c: Add driver for RDACM21 camera module")
> Signed-off-by: Jacopo Mondi <jacopo+renesas@...ndi.org>

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

> ---
>  drivers/media/i2c/rdacm21.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/media/i2c/rdacm21.c b/drivers/media/i2c/rdacm21.c
> index 50a9b0d8255d..07cf077d8efd 100644
> --- a/drivers/media/i2c/rdacm21.c
> +++ b/drivers/media/i2c/rdacm21.c
> @@ -53,7 +53,7 @@
>  #define OV490_PID			0x8080300a
>  #define OV490_VER			0x8080300b
>  #define OV490_PID_TIMEOUT		20
> -#define OV490_OUTPUT_EN_TIMEOUT		300
> +#define OV490_OUTPUT_EN_TIMEOUT		600
>  
>  #define OV490_GPIO0			BIT(0)
>  #define OV490_SPWDN0			BIT(0)
>