Re: [PATCH v2 5/7] media: synopsys: Add PHY stopstate wait for i.MX93

[Frank Li <Frank.li@nxp.com>]

On Thu, Apr 23, 2026 at 04:23:00PM +0800, Guoniu Zhou wrote:
> Implement waiting for D-PHY lanes to enter stop state on i.MX93. This
> ensures proper PHY initialization by verifying that the clock lane and
> all active data lanes have entered the stop state before proceeding with
> further operations.
>
> Signed-off-by: Guoniu Zhou <guoniu.zhou@oss.nxp.com>
> ---

Reviewed-by: Frank Li <Frank.Li@nxp.com>

> Changes in v2:
> - Removes redundant register availability check
> - Uses read_poll_timeout() with dw_mipi_csi2rx_read() instead of
>   readl_poll_timeout() with direct register address
> - Fixes stopstate condition logic
> - Check PHY stopstate after sensor enable instead of before to ensure
>   correct timing.
> - Optimize PHY stopstate polling parameters (1000us->10us, 2s->1ms) to
>   balance performance and responsiveness.
> ---
>  drivers/media/platform/synopsys/dw-mipi-csi2rx.c | 36 ++++++++++++++++++++++++
>  1 file changed, 36 insertions(+)
>
> diff --git a/drivers/media/platform/synopsys/dw-mipi-csi2rx.c b/drivers/media/platform/synopsys/dw-mipi-csi2rx.c
> index 5a2e74d055c0..8c38fe8a3f06 100644
> --- a/drivers/media/platform/synopsys/dw-mipi-csi2rx.c
> +++ b/drivers/media/platform/synopsys/dw-mipi-csi2rx.c
> @@ -11,6 +11,7 @@
>  #include <linux/clk.h>
>  #include <linux/delay.h>
>  #include <linux/io.h>
> +#include <linux/iopoll.h>
>  #include <linux/module.h>
>  #include <linux/of.h>
>  #include <linux/phy/phy.h>
> @@ -35,6 +36,8 @@
>  #define DW_REG_EXIST		BIT(31)
>  #define DW_REG(x)		(DW_REG_EXIST | (x))
>
> +#define DPHY_STOPSTATE_CLK_LANE		BIT(16)
> +
>  #define DPHY_TEST_CTRL0_TEST_CLR	BIT(0)
>
>  #define IPI_VCID_VC(x)			FIELD_PREP(GENMASK(1, 0), (x))
> @@ -65,6 +68,7 @@ enum dw_mipi_csi2rx_regs_index {
>  	DW_MIPI_CSI2RX_PHY_TST_CTRL0,
>  	DW_MIPI_CSI2RX_PHY_TST_CTRL1,
>  	DW_MIPI_CSI2RX_PHY_SHUTDOWNZ,
> +	DW_MIPI_CSI2RX_PHY_STOPSTATE,
>  	DW_MIPI_CSI2RX_IPI_DATATYPE,
>  	DW_MIPI_CSI2RX_IPI_MEM_FLUSH,
>  	DW_MIPI_CSI2RX_IPI_MODE,
> @@ -87,6 +91,7 @@ struct dw_mipi_csi2rx_drvdata {
>  	void (*dphy_assert_reset)(struct dw_mipi_csi2rx_device *csi2);
>  	void (*dphy_deassert_reset)(struct dw_mipi_csi2rx_device *csi2);
>  	void (*ipi_enable)(struct dw_mipi_csi2rx_device *csi2);
> +	int (*wait_for_phy_stopstate)(struct dw_mipi_csi2rx_device *csi2);
>  };
>
>  struct dw_mipi_csi2rx_format {
> @@ -139,6 +144,7 @@ static const u32 imx93_regs[DW_MIPI_CSI2RX_MAX] = {
>  	[DW_MIPI_CSI2RX_PHY_SHUTDOWNZ] = DW_REG(0x40),
>  	[DW_MIPI_CSI2RX_DPHY_RSTZ] = DW_REG(0x44),
>  	[DW_MIPI_CSI2RX_PHY_STATE] = DW_REG(0x48),
> +	[DW_MIPI_CSI2RX_PHY_STOPSTATE] = DW_REG(0x4c),
>  	[DW_MIPI_CSI2RX_PHY_TST_CTRL0] = DW_REG(0x50),
>  	[DW_MIPI_CSI2RX_PHY_TST_CTRL1] = DW_REG(0x54),
>  	[DW_MIPI_CSI2RX_IPI_MODE] = DW_REG(0x80),
> @@ -550,10 +556,19 @@ static int dw_mipi_csi2rx_enable_streams(struct v4l2_subdev *sd,
>  	if (ret)
>  		goto err_csi_stop;
>
> +	if (!csi2->enabled_streams &&
> +	    csi2->drvdata->wait_for_phy_stopstate) {
> +		ret = csi2->drvdata->wait_for_phy_stopstate(csi2);
> +		if (ret)
> +			goto err_disable_streams;
> +	}
> +
>  	csi2->enabled_streams |= streams_mask;
>
>  	return 0;
>
> +err_disable_streams:
> +	v4l2_subdev_disable_streams(remote_sd, remote_pad->index, mask);
>  err_csi_stop:
>  	/* Stop CSI hardware if no streams are enabled */
>  	if (!csi2->enabled_streams)
> @@ -864,11 +879,32 @@ static void imx93_csi2rx_dphy_ipi_enable(struct dw_mipi_csi2rx_device *csi2)
>  	dw_mipi_csi2rx_write(csi2, DW_MIPI_CSI2RX_IPI_MODE, val);
>  }
>
> +static int imx93_csi2rx_wait_for_phy_stopstate(struct dw_mipi_csi2rx_device *csi2)
> +{
> +	struct device *dev = csi2->dev;
> +	u32 stopstate_mask;
> +	u32 val;
> +	int ret;
> +
> +	stopstate_mask = DPHY_STOPSTATE_CLK_LANE | GENMASK(csi2->lanes_num - 1, 0);
> +
> +	ret = read_poll_timeout(dw_mipi_csi2rx_read, val,
> +				(val & stopstate_mask) == stopstate_mask,
> +				 10, 1000, true,
> +				 csi2, DW_MIPI_CSI2RX_PHY_STOPSTATE);
> +	if (ret)
> +		dev_err(dev, "lanes are not in stop state: %#x, expected %#x\n",
> +			val, stopstate_mask);
> +
> +	return ret;
> +}
> +
>  static const struct dw_mipi_csi2rx_drvdata imx93_drvdata = {
>  	.regs = imx93_regs,
>  	.dphy_assert_reset = imx93_csi2rx_dphy_assert_reset,
>  	.dphy_deassert_reset = imx93_csi2rx_dphy_deassert_reset,
>  	.ipi_enable = imx93_csi2rx_dphy_ipi_enable,
> +	.wait_for_phy_stopstate = imx93_csi2rx_wait_for_phy_stopstate,
>  };
>
>  static const struct of_device_id dw_mipi_csi2rx_of_match[] = {
>
> --
> 2.34.1
>