linux-kernel - Re: [PATCH v9 07/13] media: cadence: csi2rx: Soft reset the streams before starting capture

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Date:   Tue, 15 Aug 2023 15:10:13 +0300
From:   Tomi Valkeinen <tomi.valkeinen@...asonboard.com>
To:     Jai Luthra <j-luthra@...com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Sakari Ailus <sakari.ailus@...ux.intel.com>
Cc:     linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Mauro Carvalho Chehab <mchehab+samsung@...nel.org>,
        Maxime Ripard <mripard@...nel.org>,
        niklas.soderlund+renesas@...natech.se,
        Benoit Parrot <bparrot@...com>,
        Vaishnav Achath <vaishnav.a@...com>,
        Vignesh Raghavendra <vigneshr@...com>, nm@...com,
        devarsht@...com, a-bhatia1@...com,
        Martyn Welch <martyn.welch@...labora.com>,
        Julien Massot <julien.massot@...labora.com>
Subject: Re: [PATCH v9 07/13] media: cadence: csi2rx: Soft reset the streams
 before starting capture

On 11/08/2023 13:47, Jai Luthra wrote:
> From: Pratyush Yadav <p.yadav@...com>
> 
> This resets the stream state machines and FIFOs, giving them a clean
> slate. On J721E if the streams are not reset before starting the
> capture, the captured frame gets wrapped around vertically on every run
> after the first.
> 
> Signed-off-by: Pratyush Yadav <p.yadav@...com>
> Reviewed-by: Laurent Pinchart <laurent.pinchart@...asonboard.com>
> Reviewed-by: Maxime Ripard <mripard@...nel.org>
> Signed-off-by: Jai Luthra <j-luthra@...com>
> ---
> Changes from v8:
>      - Simplify reset sequence, minimizing delays
> 
>   drivers/media/platform/cadence/cdns-csi2rx.c | 14 +++++++++++++-
>   1 file changed, 13 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/media/platform/cadence/cdns-csi2rx.c b/drivers/media/platform/cadence/cdns-csi2rx.c
> index 933edec89520..b57e0c3b1944 100644
> --- a/drivers/media/platform/cadence/cdns-csi2rx.c
> +++ b/drivers/media/platform/cadence/cdns-csi2rx.c
> @@ -40,6 +40,7 @@
>   #define CSI2RX_STREAM_BASE(n)		(((n) + 1) * 0x100)
>   
>   #define CSI2RX_STREAM_CTRL_REG(n)		(CSI2RX_STREAM_BASE(n) + 0x000)
> +#define CSI2RX_STREAM_CTRL_SOFT_RST			BIT(4)
>   #define CSI2RX_STREAM_CTRL_START			BIT(0)
>   
>   #define CSI2RX_STREAM_DATA_CFG_REG(n)		(CSI2RX_STREAM_BASE(n) + 0x008)
> @@ -134,12 +135,23 @@ struct csi2rx_priv *v4l2_subdev_to_csi2rx(struct v4l2_subdev *subdev)
>   
>   static void csi2rx_reset(struct csi2rx_priv *csi2rx)
>   {
> +	unsigned int i;
> +
> +	/* Reset module */
>   	writel(CSI2RX_SOFT_RESET_PROTOCOL | CSI2RX_SOFT_RESET_FRONT,
>   	       csi2rx->base + CSI2RX_SOFT_RESET_REG);
> +	/* Reset individual streams. */
> +	for (i = 0; i < csi2rx->max_streams; i++) {
> +		writel(CSI2RX_STREAM_CTRL_SOFT_RST,
> +		       csi2rx->base + CSI2RX_STREAM_CTRL_REG(i));
> +	}
>   
> -	udelay(10);
> +	usleep_range(10, 20);
>   
> +	/* Clear resets */
>   	writel(0, csi2rx->base + CSI2RX_SOFT_RESET_REG);
> +	for (i = 0; i < csi2rx->max_streams; i++)
> +		writel(0, csi2rx->base + CSI2RX_STREAM_CTRL_REG(i));
>   }
>   
>   static int csi2rx_configure_ext_dphy(struct csi2rx_priv *csi2rx)
> 

Reviewed-by: Tomi Valkeinen <tomi.valkeinen@...asonboard.com>

  Tomi