[PATCH v3 5/7] media: synopsys: Add PHY stopstate wait for i.MX93

[Guoniu Zhou]

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.

Reviewed-by: Frank Li <Frank.Li at nxp.com>
Signed-off-by: Guoniu Zhou <guoniu.zhou at oss.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 92178a3dec5d..8a34aec550ad 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),
@@ -556,10 +562,19 @@ 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)
@@ -871,11 +886,32 @@ 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