drm/exynos: Enable DP clock to fix display on Exynos5250 and other

After adding display power domain for Exynos5250 in commit
2d2c9a8d ("ARM: dts: add display power domain for exynos5250") the
display on Chromebook Snow and others stopped working after boot.

The reason for this suggested Andrzej Hajda: the DP clock was disabled.
This clock is required by Display Port and is enabled by bootloader.
However when FIMD driver probing was deferred, the display power domain
was turned off. This effectively reset the value of DP clock enable
register.

When exynos-dp is later probed, the clock is not enabled and display is
not properly configured:

exynos-dp 145b0000.dp-controller: Timeout of video streamclk ok
exynos-dp 145b0000.dp-controller: unable to config video

Fixes: 2d2c9a8d ("ARM: dts: add display power domain for exynos5250")
Cc: <stable@vger.kernel.org>
Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Reported-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
Tested-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
Tested-by: Andreas Färber <afaerber@suse.de>
Signed-off-by: Inki Dae <inki.dae@samsung.com>

drivers/gpu/drm/exynos/exynos_dp_core.c

@@ -32,10 +32,16 @@
 #include <drm/bridge/ptn3460.h>
 
 #include "exynos_dp_core.h"
+#include "exynos_drm_fimd.h"
 
 #define ctx_from_connector(c)	container_of(c, struct exynos_dp_device, \
 					connector)
 
+static inline struct exynos_drm_crtc *dp_to_crtc(struct exynos_dp_device *dp)
+{
+	return to_exynos_crtc(dp->encoder->crtc);
+}
+
 static inline struct exynos_dp_device *
 display_to_dp(struct exynos_drm_display *d)
 {
@@ -1070,6 +1076,8 @@ static void exynos_dp_poweron(struct exynos_dp_device *dp)
 		}
 	}
 
+	fimd_dp_clock_enable(dp_to_crtc(dp), true);
+
 	clk_prepare_enable(dp->clock);
 	exynos_dp_phy_init(dp);
 	exynos_dp_init_dp(dp);
@@ -1094,6 +1102,8 @@ static void exynos_dp_poweroff(struct exynos_dp_device *dp)
 	exynos_dp_phy_exit(dp);
 	clk_disable_unprepare(dp->clock);
 
+	fimd_dp_clock_enable(dp_to_crtc(dp), false);
+
 	if (dp->panel) {
 		if (drm_panel_unprepare(dp->panel))
 			DRM_ERROR("failed to turnoff the panel\n");

drivers/gpu/drm/exynos/exynos_drm_fimd.c

@@ -33,6 +33,7 @@
 #include "exynos_drm_crtc.h"
 #include "exynos_drm_plane.h"
 #include "exynos_drm_iommu.h"
+#include "exynos_drm_fimd.h"
 
 /*
  * FIMD stands for Fully Interactive Mobile Display and
@@ -1191,6 +1192,24 @@ static int fimd_remove(struct platform_device *pdev)
 	return 0;
 }
 
+void fimd_dp_clock_enable(struct exynos_drm_crtc *crtc, bool enable)
+{
+	struct fimd_context *ctx = crtc->ctx;
+	u32 val;
+
+	/*
+	 * Only Exynos 5250, 5260, 5410 and 542x requires enabling DP/MIE
+	 * clock. On these SoCs the bootloader may enable it but any
+	 * power domain off/on will reset it to disable state.
+	 */
+	if (ctx->driver_data != &exynos5_fimd_driver_data)
+		return;
+
+	val = enable ? DP_MIE_CLK_DP_ENABLE : DP_MIE_CLK_DISABLE;
+	writel(DP_MIE_CLK_DP_ENABLE, ctx->regs + DP_MIE_CLKCON);
+}
+EXPORT_SYMBOL_GPL(fimd_dp_clock_enable);
+
 struct platform_driver fimd_driver = {
 	.probe		= fimd_probe,
 	.remove		= fimd_remove,

drivers/gpu/drm/exynos/exynos_drm_fimd.h

+/*
+ * Copyright (c) 2015 Samsung Electronics Co., Ltd.
+ *
+ * This program is free software; you can redistribute  it and/or modify it
+ * under  the terms of  the GNU General  Public License as published by the
+ * Free Software Foundation;  either version 2 of the  License, or (at your
+ * option) any later version.
+ */
+
+#ifndef _EXYNOS_DRM_FIMD_H_
+#define _EXYNOS_DRM_FIMD_H_
+
+extern void fimd_dp_clock_enable(struct exynos_drm_crtc *crtc, bool enable);
+
+#endif /* _EXYNOS_DRM_FIMD_H_ */

include/video/samsung_fimd.h

@@ -441,6 +441,12 @@
 #define BLENDCON_NEW_8BIT_ALPHA_VALUE		(1 << 0)
 #define BLENDCON_NEW_4BIT_ALPHA_VALUE		(0 << 0)
 
+/* Display port clock control */
+#define DP_MIE_CLKCON				0x27c
+#define DP_MIE_CLK_DISABLE			0x0
+#define DP_MIE_CLK_DP_ENABLE			0x2
+#define DP_MIE_CLK_MIE_ENABLE			0x3
+
 /* Notes on per-window bpp settings
  *
  * Value	Win0	 Win1	  Win2	   Win3	    Win 4