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Groups > linux.kernel > #1587577

[PATCH v4 23/23] drm/rockchip: dw-mipi-dsi: add reset control

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In order to fully reset the state of the MIPI controller we must assert
this reset.

This is slightly more complicated than it could be in order to maintain
compatibility with device trees that do not specify the reset property.

Signed-off-by: John Keeping <john@metanate.com>
Reviewed-by: Chris Zhong <zyw@rock-chips.com>
---
v4:
- Fix error check for devm_reset_control_get() to use ENOENT
v3:
- Add Chris' Reviewed-by
Unchanged in v2
---
 drivers/gpu/drm/rockchip/dw-mipi-dsi.c | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/drivers/gpu/drm/rockchip/dw-mipi-dsi.c b/drivers/gpu/drm/rockchip/dw-mipi-dsi.c
index 0c4bae711e84..30da75667334 100644
--- a/drivers/gpu/drm/rockchip/dw-mipi-dsi.c
+++ b/drivers/gpu/drm/rockchip/dw-mipi-dsi.c
@@ -13,6 +13,7 @@
 #include <linux/module.h>
 #include <linux/of_device.h>
 #include <linux/regmap.h>
+#include <linux/reset.h>
 #include <linux/mfd/syscon.h>
 #include <drm/drm_atomic_helper.h>
 #include <drm/drm_crtc.h>
@@ -1144,6 +1145,7 @@ static int dw_mipi_dsi_bind(struct device *dev, struct device *master,
 			of_match_device(dw_mipi_dsi_dt_ids, dev);
 	const struct dw_mipi_dsi_plat_data *pdata = of_id->data;
 	struct platform_device *pdev = to_platform_device(dev);
+	struct reset_control *apb_rst;
 	struct drm_device *drm = data;
 	struct dw_mipi_dsi *dsi;
 	struct resource *res;
@@ -1182,6 +1184,35 @@ static int dw_mipi_dsi_bind(struct device *dev, struct device *master,
 		return ret;
 	}
 
+	/*
+	 * Note that the reset was not defined in the initial device tree, so
+	 * we have to be prepared for it not being found.
+	 */
+	apb_rst = devm_reset_control_get(dev, "apb");
+	if (IS_ERR(apb_rst)) {
+		ret = PTR_ERR(apb_rst);
+		if (ret == -ENOENT) {
+			apb_rst = NULL;
+		} else {
+			dev_err(dev, "Unable to get reset control: %d\n", ret);
+			return ret;
+		}
+	}
+
+	if (apb_rst) {
+		ret = clk_prepare_enable(dsi->pclk);
+		if (ret) {
+			dev_err(dev, "%s: Failed to enable pclk\n", __func__);
+			return ret;
+		}
+
+		reset_control_assert(apb_rst);
+		usleep_range(10, 20);
+		reset_control_deassert(apb_rst);
+
+		clk_disable_unprepare(dsi->pclk);
+	}
+
 	ret = clk_prepare_enable(dsi->pllref_clk);
 	if (ret) {
 		dev_err(dev, "%s: Failed to enable pllref_clk\n", __func__);
-- 
2.12.0.rc0.230.gf625d4cdb9.dirty

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[PATCH v4 00/23] drm/rockchip: MIPI fixes & improvements John Keeping <john@metanate.com> - 2017-02-24 14:00 +0100
  [PATCH v4 18/23] drm/rockchip: dw-mipi-dsi: use specific poll helper John Keeping <john@metanate.com> - 2017-02-24 14:00 +0100
  [PATCH v4 13/23] drm/rockchip: dw-mipi-dsi: fix escape clock rate John Keeping <john@metanate.com> - 2017-02-24 14:00 +0100
  [PATCH v4 23/23] drm/rockchip: dw-mipi-dsi: add reset control John Keeping <john@metanate.com> - 2017-02-24 14:00 +0100
  [PATCH v4 12/23] drm/rockchip: dw-mipi-dsi: allow commands in panel_disable John Keeping <john@metanate.com> - 2017-02-24 14:00 +0100
  [PATCH v4 02/23] drm/rockchip: dw-mipi-dsi: pass mode in where needed John Keeping <john@metanate.com> - 2017-02-24 14:00 +0100
  [PATCH v4 07/23] drm/rockchip: dw-mipi-dsi: include bad value in error message John Keeping <john@metanate.com> - 2017-02-24 14:00 +0100
  [PATCH v4 21/23] drm/rockchip: dw-mipi-dsi: defer probe if panel is not loaded John Keeping <john@metanate.com> - 2017-02-24 14:00 +0100
  [PATCH v4 19/23] drm/rockchip: dw-mipi-dsi: use positive check for N{H,V}SYNC John Keeping <john@metanate.com> - 2017-02-24 14:00 +0100
  [PATCH v4 06/23] drm/rockchip: dw-mipi-dsi: avoid out-of-bounds read on tx_buf John Keeping <john@metanate.com> - 2017-02-24 14:00 +0100
  [PATCH v4 15/23] drm/rockchip: dw-mipi-dsi: configure PHY before enabling John Keeping <john@metanate.com> - 2017-02-24 14:00 +0100
  [PATCH v4 08/23] drm/rockchip: dw-mipi-dsi: respect message flags John Keeping <john@metanate.com> - 2017-02-24 14:00 +0100
  [PATCH v4 04/23] drm/rockchip: dw-mipi-dsi: fix command header writes John Keeping <john@metanate.com> - 2017-02-24 14:00 +0100
  [PATCH v4 10/23] drm/rockchip: dw-mipi-dsi: don't assume buffer is aligned John Keeping <john@metanate.com> - 2017-02-24 14:00 +0100
  [PATCH v4 11/23] drm/rockchip: dw-mipi-dsi: prepare panel after phy init John Keeping <john@metanate.com> - 2017-02-24 14:00 +0100
  [PATCH v4 17/23] drm/rockchip: dw-mipi-dsi: improve PLL configuration John Keeping <john@metanate.com> - 2017-02-24 14:00 +0100
  [PATCH v4 09/23] drm/rockchip: dw-mipi-dsi: only request HS clock when required John Keeping <john@metanate.com> - 2017-02-24 14:00 +0100
  [PATCH v4 03/23] drm/rockchip: dw-mipi-dsi: remove mode_set hook John Keeping <john@metanate.com> - 2017-02-24 14:00 +0100
  [PATCH v4 05/23] drm/rockchip: dw-mipi-dsi: fix generic packet status check John Keeping <john@metanate.com> - 2017-02-24 14:00 +0100
  [PATCH v4 01/23] drm/rockchip: dw-mipi-dsi: don't configure hardware in mode_set for MIPI John Keeping <john@metanate.com> - 2017-02-24 14:00 +0100
  [PATCH v4 16/23] drm/rockchip: dw-mipi-dsi: properly configure PHY timing John Keeping <john@metanate.com> - 2017-02-24 14:00 +0100
  [PATCH v4 22/23] drm/rockchip: dw-mipi-dsi: support non-burst modes John Keeping <john@metanate.com> - 2017-02-24 14:10 +0100
  Re: [PATCH v4 00/23] drm/rockchip: MIPI fixes & improvements Mark yao <mark.yao@rock-chips.com> - 2017-02-27 02:50 +0100
  Re: [PATCH v4 00/23] drm/rockchip: MIPI fixes & improvements Chris Zhong <zyw@rock-chips.com> - 2017-02-27 04:40 +0100

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