[PATCH v4] drm/exynos: enable fimd clocks in probe before accessing fimd registers

[Rahul Sharma]

From: Rahul Sharma <Rahul.Sharma at samsung.com>

Fimd probe is accessing fimd Registers without enabling the fimd
gate clocks. If FIMD clocks are kept disabled in Uboot or disbaled
during kernel boottime, the system hangs during boottime.

This issue got surfaced when verifying with sysmmu enabled. Probe of
fimd Sysmmu enables the master clock before accessing sysmmu regs and
then disables. Later fimd probe tries to read the register without
enabling the clock which is wrong and hangs the system.

Signed-off-by: Rahul Sharma <Rahul.Sharma at samsung.com>
---
v4:
	1) Added clk_disable for prev clock when clk_enable fails.
v3:
	1) Added checks for clk_enable.
v2:
	Rebase.

 drivers/gpu/drm/exynos/exynos_drm_fimd.c |   18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/exynos/exynos_drm_fimd.c b/drivers/gpu/drm/exynos/exynos_drm_fimd.c
index bd30d0c..30ccd67 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_fimd.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_fimd.c
@@ -898,16 +898,32 @@ static int fimd_bind(struct device *dev, struct device *master, void *data)
 {
 	struct fimd_context *ctx = fimd_manager.ctx;
 	struct drm_device *drm_dev = data;
-	int win;
+	int win, ret;
 
 	fimd_mgr_initialize(&fimd_manager, drm_dev);
 	exynos_drm_crtc_create(&fimd_manager);
 	if (ctx->display)
 		exynos_drm_create_enc_conn(drm_dev, ctx->display);
 
+	ret = clk_prepare_enable(ctx->bus_clk);
+	if (ret) {
+		dev_err(dev, "bus clock enable failed.\n");
+		return ret;
+	}
+
+	ret = clk_prepare_enable(ctx->lcd_clk);
+	if (ret) {
+		dev_err(dev, "lcd clock enable failed.\n");
+		clk_disable_unprepare(ctx->bus_clk);
+		return ret;
+	}
+
 	for (win = 0; win < WINDOWS_NR; win++)
 		fimd_clear_win(ctx, win);
 
+	clk_disable_unprepare(ctx->lcd_clk);
+	clk_disable_unprepare(ctx->bus_clk);
+
 	return 0;
 
 }
-- 
1.7.9.5