linux-kernel - Re: [PATCH v4 03/11] media: cadence: csi2rx: Soft reset the streams before starting capture

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Date:   Thu, 7 Oct 2021 02:41:20 +0300
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Pratyush Yadav <p.yadav@...com>
Cc:     Mauro Carvalho Chehab <mchehab@...nel.org>,
        Nikhil Devshatwar <nikhil.nd@...com>,
        Tomi Valkeinen <tomi.valkeinen@...asonboard.com>,
        Vignesh Raghavendra <vigneshr@...com>,
        Benoit Parrot <bparrot@...com>,
        Maxime Ripard <mripard@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Sakari Ailus <sakari.ailus@...ux.intel.com>,
        Niklas Söderlund 
        <niklas.soderlund+renesas@...natech.se>,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-media@...r.kernel.org
Subject: Re: [PATCH v4 03/11] media: cadence: csi2rx: Soft reset the streams
 before starting capture

Hi Pratyush,

Thank you for the patch.

On Wed, Sep 15, 2021 at 05:32:32PM +0530, Pratyush Yadav wrote:
> 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>
> ---
> 
> (no changes since v1)
> 
>  drivers/media/platform/cadence/cdns-csi2rx.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/drivers/media/platform/cadence/cdns-csi2rx.c b/drivers/media/platform/cadence/cdns-csi2rx.c
> index c06e039a1aa8..e05d76394cd6 100644
> --- a/drivers/media/platform/cadence/cdns-csi2rx.c
> +++ b/drivers/media/platform/cadence/cdns-csi2rx.c
> @@ -39,6 +39,7 @@
>  #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)
> @@ -135,12 +136,22 @@ struct csi2rx_priv *v4l2_subdev_to_csi2rx(struct v4l2_subdev *subdev)
>  
>  static void csi2rx_reset(struct csi2rx_priv *csi2rx)
>  {
> +	int i;

i is always positive, it can be an unsigned int. With this,

Reviewed-by: Laurent Pinchart <laurent.pinchart@...asonboard.com>

> +
>  	writel(CSI2RX_SOFT_RESET_PROTOCOL | CSI2RX_SOFT_RESET_FRONT,
>  	       csi2rx->base + CSI2RX_SOFT_RESET_REG);
>  
>  	udelay(10);
>  
>  	writel(0, 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));
> +		usleep_range(10, 20);
> +		writel(0, csi2rx->base + CSI2RX_STREAM_CTRL_REG(i));
> +	}
>  }
>  
>  static int csi2rx_configure_external_dphy(struct csi2rx_priv *csi2rx)

-- 
Regards,

Laurent Pinchart