linux-kernel - Re: [PATCH v8 11/16] media: cadence: csi2rx: Fix stream data configuration

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Date:   Tue, 1 Aug 2023 17:17:17 +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>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>
Cc:     linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        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
Subject: Re: [PATCH v8 11/16] media: cadence: csi2rx: Fix stream data
 configuration

On 31/07/2023 11:29, Jai Luthra wrote:
> From: Pratyush Yadav <p.yadav@...com>
> 
> Firstly, there is no VC_EN bit present in the STREAM_DATA_CFG register.
> Bit 31 is part of the VL_SELECT field. Remove it completely.
> 
> Secondly, it makes little sense to enable ith virtual channel for ith
> stream. Sure, there might be a use-case that demands it. But there might
> also be a use case that demands all streams to use the 0th virtual
> channel. Prefer this case over the former because it is less arbitrary
> and also makes it very clear what the limitations of the current driver
> is instead of giving a false impression that multiple virtual channels
> are supported.
> 
> Signed-off-by: Pratyush Yadav <p.yadav@...com>
> Signed-off-by: Jai Luthra <j-luthra@...com>
> Reviewed-by: Laurent Pinchart <laurent.pinchart@...asonboard.com>
> ---
> v7->v8: No change
> 
>   drivers/media/platform/cadence/cdns-csi2rx.c | 8 +++++---
>   1 file changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/media/platform/cadence/cdns-csi2rx.c b/drivers/media/platform/cadence/cdns-csi2rx.c
> index a17ef88dff82..cde7fd6463e1 100644
> --- a/drivers/media/platform/cadence/cdns-csi2rx.c
> +++ b/drivers/media/platform/cadence/cdns-csi2rx.c
> @@ -49,7 +49,6 @@
>   #define CSI2RX_STREAM_STATUS_RDY			BIT(31)
>   
>   #define CSI2RX_STREAM_DATA_CFG_REG(n)		(CSI2RX_STREAM_BASE(n) + 0x008)
> -#define CSI2RX_STREAM_DATA_CFG_EN_VC_SELECT		BIT(31)
>   #define CSI2RX_STREAM_DATA_CFG_VC_SELECT(n)		BIT((n) + 16)
>   
>   #define CSI2RX_STREAM_CFG_REG(n)		(CSI2RX_STREAM_BASE(n) + 0x00c)
> @@ -275,8 +274,11 @@ static int csi2rx_start(struct csi2rx_priv *csi2rx)
>   		writel(CSI2RX_STREAM_CFG_FIFO_MODE_LARGE_BUF,
>   		       csi2rx->base + CSI2RX_STREAM_CFG_REG(i));
>   
> -		writel(CSI2RX_STREAM_DATA_CFG_EN_VC_SELECT |
> -		       CSI2RX_STREAM_DATA_CFG_VC_SELECT(i),
> +		/*
> +		 * Enable one virtual channel. When multiple virtual channels
> +		 * are supported this will have to be changed.
> +		 */
> +		writel(CSI2RX_STREAM_DATA_CFG_VC_SELECT(0),
>   		       csi2rx->base + CSI2RX_STREAM_DATA_CFG_REG(i));
>   
>   		writel(CSI2RX_STREAM_CTRL_START,
> 

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

  Tomi