[media] s5p-mfc: Use clock gating only on MFC v5 hardware

Newer MFC hardware have internal clock gating feature, so additional
software-triggered clock gating sometimes causes misbehavior of the MFC
firmware and results in freeze or crash. This patch changes the driver
to use software-triggered clock gating only when working with v5 MFC
hardware, where it has been proven to work properly.

Signed-off-by: Marek Szyprowski <[e-mail]>
Signed-off-by: Sylwester Nawrocki <[e-mail]>
Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

drivers/media/platform/s5p-mfc/s5p_mfc.c

···
 	.buf_size	= &buf_size_v5,
 	.buf_align	= &mfc_buf_align_v5,
 	.fw_name[0]	= "s5p-mfc.fw",
+	.use_clock_gating = true,
 };
 
 static struct s5p_mfc_buf_size_v6 mfc_buf_size_v6 = {

drivers/media/platform/s5p-mfc/s5p_mfc_common.h

···
 struct s5p_mfc_pm {
 	struct clk	*clock;
 	struct clk	*clock_gate;
+	bool		use_clock_gating;
 	atomic_t	power;
 	struct device	*device;
 };
···
 	struct s5p_mfc_buf_size *buf_size;
 	struct s5p_mfc_buf_align *buf_align;
 	char	*fw_name[MFC_FW_MAX_VERSIONS];
+	bool		use_clock_gating;
 };
 
 /**

drivers/media/platform/s5p-mfc/s5p_mfc_pm.c

···
 
 	pm = &dev->pm;
 	p_dev = dev;
+	pm->use_clock_gating = dev->variant->use_clock_gating;
 	pm->clock_gate = clk_get(&dev->plat_dev->dev, MFC_GATE_CLK_NAME);
 	if (IS_ERR(pm->clock_gate)) {
 		mfc_err("Failed to get clock-gating control\n");
···
 	atomic_inc(&clk_ref);
 	mfc_debug(3, "+ %d\n", atomic_read(&clk_ref));
 #endif
+	if (!pm->use_clock_gating)
+		return 0;
 	if (!IS_ERR_OR_NULL(pm->clock_gate))
 		ret = clk_enable(pm->clock_gate);
 	return ret;
···
 	atomic_dec(&clk_ref);
 	mfc_debug(3, "- %d\n", atomic_read(&clk_ref));
 #endif
+	if (!pm->use_clock_gating)
+		return;
 	if (!IS_ERR_OR_NULL(pm->clock_gate))
 		clk_disable(pm->clock_gate);
 }
 
 int s5p_mfc_power_on(void)
 {
+	int ret = 0;
+
 #ifdef CONFIG_PM
-	return pm_runtime_get_sync(pm->device);
+	ret = pm_runtime_get_sync(pm->device);
+	if (ret)
+		return ret;
 #else
 	atomic_set(&pm->power, 1);
-	return 0;
 #endif
+	if (!pm->use_clock_gating && !IS_ERR_OR_NULL(pm->clock_gate))
+		ret = clk_enable(pm->clock_gate);
+	return ret;
 }
 
 int s5p_mfc_power_off(void)
 {
+	if (!pm->use_clock_gating && !IS_ERR_OR_NULL(pm->clock_gate))
+		clk_disable(pm->clock_gate);
 #ifdef CONFIG_PM
 	return pm_runtime_put_sync(pm->device);
 #else