[RFT PATCH] drm/exynos: Enable DP clock to fix display on Exynos5250 and other

[Krzysztof Kozlowski]

After adding display power domain for Exynos5250 in commit
2d2c9a8d0a4f ("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

Signed-off-by: Krzysztof Kozlowski <k.kozlowski at samsung.com>
Reported-by: Javier Martinez Canillas <javier.martinez at collabora.co.uk>
Fixes: 2d2c9a8d0a4f ("ARM: dts: add display power domain for exynos5250")
Cc: <stable at vger.kernel.org>

---

This should fix issue reported by Javier [1][2].

Tested on Chromebook Snow (Exynos 5250). More testing would be great,
especially on other Exynos 5xxx products.

[1] http://thread.gmane.org/gmane.linux.kernel.samsung-soc/43889
[2] http://thread.gmane.org/gmane.linux.ports.arm.kernel/400290
---
 drivers/gpu/drm/exynos/exynos_dp_core.c  | 10 ++++++++++
 drivers/gpu/drm/exynos/exynos_drm_fimd.c | 19 +++++++++++++++++++
 include/video/samsung_fimd.h             |  6 ++++++
 3 files changed, 35 insertions(+)

diff --git a/drivers/gpu/drm/exynos/exynos_dp_core.c b/drivers/gpu/drm/exynos/exynos_dp_core.c
index bf17a60b40ed..1dbfba58f909 100644
--- a/drivers/gpu/drm/exynos/exynos_dp_core.c
+++ b/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");
diff --git a/drivers/gpu/drm/exynos/exynos_drm_fimd.c b/drivers/gpu/drm/exynos/exynos_drm_fimd.c
index c300e22da8ac..bdf0818dc8f5 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_fimd.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_fimd.c
@@ -32,6 +32,7 @@
 #include "exynos_drm_fbdev.h"
 #include "exynos_drm_crtc.h"
 #include "exynos_drm_iommu.h"
+#include "exynos_drm_fimd.h"
 
 /*
  * FIMD stands for Fully Interactive Mobile Display and
@@ -1231,6 +1232,24 @@ 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,
diff --git a/include/video/samsung_fimd.h b/include/video/samsung_fimd.h
index a20e4a3a8b15..847a0a2b399c 100644
--- a/include/video/samsung_fimd.h
+++ b/include/video/samsung_fimd.h
@@ -436,6 +436,12 @@
 #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
-- 
1.9.1