[PATCH] drm/stm: dsi: Enable wrapper glue regulator early

[Marek Vasut]

Certain DSI bridge chips like TC358767/TC358867/TC9595 expect the DSI D0
data lane to be in LP-11 state when released from reset. Currently the
STM32MP157 DSI host wrapper glue logic keeps D0 data lane in LP-00 state
until DSI init happens, which confuses the TC358767 into entering some
sort of test mode and the chip cannot be brought out of this test mode
in any way.

Enable the wrapper glue logic regulator in probe callback already and
disable it in remove callback to satisfy this requirement. The D0 data
lane is in LP-11 mode when the TC358767 bridge chip is brought up and
the chip is not confused anymore.

Signed-off-by: Marek Vasut <marex at denx.de>
Cc: Alexandre Torgue <alexandre.torgue at foss.st.com>
Cc: Antonio Borneo <antonio.borneo at foss.st.com>
Cc: Philippe Cornu <philippe.cornu at foss.st.com>
Cc: Raphael Gallais-Pou <raphael.gallais-pou at foss.st.com>
Cc: Robert Foss <robert.foss at linaro.org>
Cc: Yannick Fertre <yannick.fertre at foss.st.com>
---
 drivers/gpu/drm/stm/dw_mipi_dsi-stm.c | 30 +++++++++++++++++++++++----
 1 file changed, 26 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/stm/dw_mipi_dsi-stm.c b/drivers/gpu/drm/stm/dw_mipi_dsi-stm.c
index 89897d5f5c72..c403633ffeae 100644
--- a/drivers/gpu/drm/stm/dw_mipi_dsi-stm.c
+++ b/drivers/gpu/drm/stm/dw_mipi_dsi-stm.c
@@ -194,16 +194,29 @@ static int dsi_pll_get_params(struct dw_mipi_dsi_stm *dsi,
 	return 0;
 }
 
+static int dw_mipi_dsi_phy_regulator_on(struct dw_mipi_dsi_stm *dsi)
+{
+	u32 val;
+
+	/* Enable the regulator */
+	dsi_set(dsi, DSI_WRPCR, WRPCR_REGEN | WRPCR_BGREN);
+	return readl_poll_timeout(dsi->base + DSI_WISR, val, val & WISR_RRS,
+				  SLEEP_US, TIMEOUT_US);
+}
+
+static void dw_mipi_dsi_phy_regulator_off(struct dw_mipi_dsi_stm *dsi)
+{
+	/* Disable the regulator */
+	dsi_clear(dsi, DSI_WRPCR, WRPCR_REGEN | WRPCR_BGREN);
+}
+
 static int dw_mipi_dsi_phy_init(void *priv_data)
 {
 	struct dw_mipi_dsi_stm *dsi = priv_data;
 	u32 val;
 	int ret;
 
-	/* Enable the regulator */
-	dsi_set(dsi, DSI_WRPCR, WRPCR_REGEN | WRPCR_BGREN);
-	ret = readl_poll_timeout(dsi->base + DSI_WISR, val, val & WISR_RRS,
-				 SLEEP_US, TIMEOUT_US);
+	ret = dw_mipi_dsi_phy_regulator_on(dsi);
 	if (ret)
 		DRM_DEBUG_DRIVER("!TIMEOUT! waiting REGU, let's continue\n");
 
@@ -499,8 +512,16 @@ static int dw_mipi_dsi_stm_probe(struct platform_device *pdev)
 	}
 
 	dsi->hw_version = dsi_read(dsi, DSI_VERSION) & VERSION;
+
+	ret = dw_mipi_dsi_phy_regulator_on(dsi);
 	clk_disable_unprepare(pclk);
 
+	if (ret) {
+		DRM_ERROR("%s: Failed to enable wrapper regulator, ret=%d\n",
+			  __func__, ret);
+		goto err_dsi_probe;
+	}
+
 	if (dsi->hw_version != HWVER_130 && dsi->hw_version != HWVER_131) {
 		ret = -ENODEV;
 		DRM_ERROR("bad dsi hardware version\n");
@@ -542,6 +563,7 @@ static int dw_mipi_dsi_stm_remove(struct platform_device *pdev)
 	struct dw_mipi_dsi_stm *dsi = platform_get_drvdata(pdev);
 
 	dw_mipi_dsi_remove(dsi->dsi);
+	dw_mipi_dsi_phy_regulator_off(dsi);
 	clk_disable_unprepare(dsi->pllref_clk);
 	regulator_disable(dsi->vdd_supply);
 
-- 
2.35.1