[PATCH v5] 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>
---
v5:
        1) Added pm_runtime_get_sync to enable the Display power domain.
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 |   35 +++++++++++++++++++++++++++++-
 1 file changed, 34 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..6a30415 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_fimd.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_fimd.c
@@ -898,18 +898,51 @@ 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 = pm_runtime_get_sync(ctx->dev);
+	if (ret) {
+		dev_err(dev, "pm runtime get has failed.\n");
+		return ret;
+	}
+
+	ret = clk_prepare_enable(ctx->bus_clk);
+	if (ret) {
+		dev_err(dev, "bus clock enable failed.\n");
+		goto bus_clk_err;
+	}
+
+	ret = clk_prepare_enable(ctx->lcd_clk);
+	if (ret) {
+		dev_err(dev, "lcd clock enable failed.\n");
+		goto lcd_clk_err;
+	}
+
 	for (win = 0; win < WINDOWS_NR; win++)
 		fimd_clear_win(ctx, win);
 
+	clk_disable_unprepare(ctx->lcd_clk);
+	clk_disable_unprepare(ctx->bus_clk);
+
+	ret = pm_runtime_put_sync(ctx->dev);
+	if (ret) {
+		dev_err(dev, "pm runtime put has failed.\n");
+		goto pm_put_err;
+	}
+
 	return 0;
 
+lcd_clk_err:
+	clk_disable_unprepare(ctx->bus_clk);
+bus_clk_err:
+	pm_runtime_put_sync(ctx->dev);
+pm_put_err:
+	return ret;
 }
 
 static void fimd_unbind(struct device *dev, struct device *master,
-- 
1.7.9.5