[RFC] drm/exynos: move hdmi clk disable out of pm ops

[Gustavo Padovan <gustavo@padovan.org>]

From: Prathyush K <prathyush.k@samsung.com>

When VPLL clock of less than 140 MHz was used and all the three
clocks - hdmiphy, hdmi, sclk_hdmi are disabled, the system hangs
during S2R when HDMI is connected. Since we want to use a vpll
clock of 70.5 MHz, we cannot disable these 3 clocks before suspending.
This patch moves the clk enable/disable of hdmi and sclk_hdmi
outside of the pm ops. Now system suspends and resumes with HDMI
connected with VPLL set at 70.5 MHz.

Signed-off-by: Prathyush K <prathyush.k@samsung.com>
Signed-off-by: Andrew Bresticker <abrestic@chromium.org>
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>

---
This work depends on the HDMI support patches from Javier:
https://lkml.org/lkml/2015/1/20/235

This patch comes from a downstream tree (Google chormeOS) and it is
authored by a Samsung employee, but we still think this may not fix
the real cause of the bug, there might be something else that we
haven't found that could be the cause of this issue. Anyone has some
comment to add here?
---
 drivers/gpu/drm/exynos/exynos_hdmi.c | 17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/exynos/exynos_hdmi.c b/drivers/gpu/drm/exynos/exynos_hdmi.c
index 6aa0d65..7a473cb 100644
--- a/drivers/gpu/drm/exynos/exynos_hdmi.c
+++ b/drivers/gpu/drm/exynos/exynos_hdmi.c
@@ -2064,9 +2064,6 @@ static void hdmi_poweron(struct exynos_drm_display *display)
 	regmap_update_bits(hdata->pmureg, PMU_HDMI_PHY_CONTROL,
 			PMU_HDMI_PHY_ENABLE_BIT, 1);
 
-	clk_prepare_enable(res->hdmi);
-	clk_prepare_enable(res->sclk_hdmi);
-
 	hdmiphy_poweron(hdata);
 	hdmi_commit(display);
 }
@@ -2088,9 +2085,6 @@ static void hdmi_poweroff(struct exynos_drm_display *display)
 
 	cancel_delayed_work(&hdata->hotplug_work);
 
-	clk_disable_unprepare(res->sclk_hdmi);
-	clk_disable_unprepare(res->hdmi);
-
 	/* reset pmu hdmiphy control bit to disable hdmiphy */
 	regmap_update_bits(hdata->pmureg, PMU_HDMI_PHY_CONTROL,
 			PMU_HDMI_PHY_ENABLE_BIT, 0);
@@ -2254,6 +2248,14 @@ static int hdmi_resources_init(struct hdmi_context *hdata)
 	} else
 		res->reg_hdmi_en = NULL;
 
+	/*
+	 * These two clocks are not moved into hdmi_poweron/off since system
+	 * fails to suspend if VPLL clock of 70.5 MHz is used and these
+	 * clocks are disabled before suspend. So enable them here.
+	 */
+	clk_prepare_enable(res->sclk_hdmi);
+	clk_prepare_enable(res->hdmi);
+
 	return ret;
 fail:
 	DRM_ERROR("HDMI resource init - failed\n");
@@ -2516,6 +2518,9 @@ static int hdmi_remove(struct platform_device *pdev)
 	if (hdata->res.reg_hdmi_en)
 		regulator_disable(hdata->res.reg_hdmi_en);
 
+	clk_disable_unprepare(hdata->res.sclk_hdmi);
+	clk_disable_unprepare(hdata->res.hdmi);
+
 	if (hdata->hdmiphy_port)
 		put_device(&hdata->hdmiphy_port->dev);
 	put_device(&hdata->ddc_adpt->dev);
-- 
1.9.3