Re: [PATCH v3 6/9] media: cadence: Add operation on reset

Laurent Pinchart
2023-04-04T05:06:14Z

Hi Jack,

Thank you for the patch.

On Fri, Mar 31, 2023 at 08:18:23PM +0800, Jack Zhu wrote:
> Add operation on reset for Cadence MIPI-CSI2 RX Controller.
>
> Signed-off-by: Jack Zhu <jack.zhu@starfivetech.com>
> ---
> drivers/media/platform/cadence/cdns-csi2rx.c | 30 ++++++++++++++++++++
> 1 file changed, 30 insertions(+)
>
> diff --git a/drivers/media/platform/cadence/cdns-csi2rx.c b/drivers/media/platform/cadence/cdns-csi2rx.c
> index cc3ebb0d96f6..a1555cedb349 100644
> --- a/drivers/media/platform/cadence/cdns-csi2rx.c
> +++ b/drivers/media/platform/cadence/cdns-csi2rx.c
> @@ -13,6 +13,7 @@
> #include <linux/of_graph.h>
> #include <linux/phy/phy.h>
> #include <linux/platform_device.h>
> +#include <linux/reset.h>
> #include <linux/slab.h>
>
> #include <media/v4l2-ctrls.h>
> @@ -68,6 +69,9 @@ struct csi2rx_priv {
> struct clk *sys_clk;
> struct clk *p_clk;
> struct clk *pixel_clk[CSI2RX_STREAMS_MAX];
> + struct reset_control *sys_rst;
> + struct reset_control *p_rst;
> + struct reset_control *pixel_rst[CSI2RX_STREAMS_MAX];
> struct phy *dphy;
>
> u8 lanes[CSI2RX_LANES_MAX];
> @@ -112,6 +116,7 @@ static int csi2rx_start(struct csi2rx_priv *csi2rx)
> if (ret)
> return ret;
>
> + reset_control_deassert(csi2rx->p_rst);
> csi2rx_reset(csi2rx);
>
> reg = csi2rx->num_lanes << 8;
> @@ -154,6 +159,8 @@ static int csi2rx_start(struct csi2rx_priv *csi2rx)
> if (ret)
> goto err_disable_pixclk;

The loop after the err_disable_pixclk label should assert the
pixel_rst[i] reset.

>
> + reset_control_deassert(csi2rx->pixel_rst[i]);
> +
> writel(CSI2RX_STREAM_CFG_FIFO_MODE_LARGE_BUF,
> csi2rx->base + CSI2RX_STREAM_CFG_REG(i));
>
> @@ -169,6 +176,7 @@ static int csi2rx_start(struct csi2rx_priv *csi2rx)
> if (ret)
> goto err_disable_pixclk;
>
> + reset_control_deassert(csi2rx->sys_rst);
> clk_disable_unprepare(csi2rx->p_clk);
>
> return 0;
> @@ -188,14 +196,17 @@ static void csi2rx_stop(struct csi2rx_priv *csi2rx)
> unsigned int i;
>
> clk_prepare_enable(csi2rx->p_clk);
> + reset_control_assert(csi2rx->sys_rst);
> clk_disable_unprepare(csi2rx->sys_clk);
>
> for (i = 0; i < csi2rx->max_streams; i++) {
> writel(0, csi2rx->base + CSI2RX_STREAM_CTRL_REG(i));
>
> + reset_control_assert(csi2rx->pixel_rst[i]);
> clk_disable_unprepare(csi2rx->pixel_clk[i]);
> }
>
> + reset_control_assert(csi2rx->p_rst);
> clk_disable_unprepare(csi2rx->p_clk);
>
> if (v4l2_subdev_call(csi2rx->source_subdev, video, s_stream, false))
> @@ -299,6 +310,17 @@ static int csi2rx_get_resources(struct csi2rx_priv *csi2rx,
> return PTR_ERR(csi2rx->p_clk);
> }
>
> + csi2rx->sys_rst =
> + devm_reset_control_get_optional_exclusive(&pdev->dev,
> + "sys_rst");

You can write this on two lines:

csi2rx->sys_rst = devm_reset_control_get_optional_exclusive(&pdev->dev,
"sys_rst");
> + if (IS_ERR(csi2rx->sys_rst))
> + return PTR_ERR(csi2rx->sys_rst);
> +
> + csi2rx->p_rst =
> + devm_reset_control_get_optional_exclusive(&pdev->dev, "p_rst");

And here,

csi2rx->p_rst = devm_reset_control_get_optional_exclusive(&pdev->dev,
"p_rst");

would be the same number of lines but more readable in my opinion.

> + if (IS_ERR(csi2rx->p_rst))
> + return PTR_ERR(csi2rx->p_rst);
> +
> csi2rx->dphy = devm_phy_optional_get(&pdev->dev, "dphy");
> if (IS_ERR(csi2rx->dphy)) {
> dev_err(&pdev->dev, "Couldn't get external D-PHY\n");
> @@ -350,6 +372,7 @@ static int csi2rx_get_resources(struct csi2rx_priv *csi2rx,
>
> for (i = 0; i < csi2rx->max_streams; i++) {
> char clk_name[16];
> + char rst_name[16];

You don't need two variables, you can rename clk_name to name, and use
it for both clk and rst.

With these small issues addressed you can add my

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

in the next version.

>
> snprintf(clk_name, sizeof(clk_name), "pixel_if%u_clk", i);
> csi2rx->pixel_clk[i] = devm_clk_get(&pdev->dev, clk_name);
> @@ -357,6 +380,13 @@ static int csi2rx_get_resources(struct csi2rx_priv *csi2rx,
> dev_err(&pdev->dev, "Couldn't get clock %s\n", clk_name);
> return PTR_ERR(csi2rx->pixel_clk[i]);
> }
> +
> + snprintf(rst_name, sizeof(rst_name), "pixel_if%u_rst", i);
> + csi2rx->pixel_rst[i] =
> + devm_reset_control_get_optional_exclusive(&pdev->dev,
> + rst_name);
> + if (IS_ERR(csi2rx->pixel_rst[i]))
> + return PTR_ERR(csi2rx->pixel_rst[i]);
> }
>
> return 0;

--
Regards,

Laurent Pinchart