[PATCH] simplefb: Separate clk / regulator get and enable steps

[Hans de Goede]

Currently when a simplefb needs both clocks and regulators and one
of the regulators returns -EPROBE_DEFER when we try to get it, we end
up disabling the clocks. This causes the screen to go blank; and in some
cases my cause hardware state to be lost resulting in the framebuffer not
working at all.

This commit splits the get and enable steps and only enables
clocks and regulators after successfully getting all of them,
fixing the disabling of the clocks which were left enabled by
the firmware setting up the simplefb.

Signed-off-by: Hans de Goede <hdegoede at redhat.com>
---
 drivers/video/fbdev/simplefb.c | 56 ++++++++++++++++++++++++++++++------------
 1 file changed, 40 insertions(+), 16 deletions(-)

diff --git a/drivers/video/fbdev/simplefb.c b/drivers/video/fbdev/simplefb.c
index 61f799a..a3c44ec 100644
--- a/drivers/video/fbdev/simplefb.c
+++ b/drivers/video/fbdev/simplefb.c
@@ -180,10 +180,12 @@ static int simplefb_parse_pd(struct platform_device *pdev,
 struct simplefb_par {
 	u32 palette[PSEUDO_PALETTE_SIZE];
 #if defined CONFIG_OF && defined CONFIG_COMMON_CLK
+	bool clks_enabled;
 	unsigned int clk_count;
 	struct clk **clks;
 #endif
 #if defined CONFIG_OF && defined CONFIG_REGULATOR
+	bool regulators_enabled;
 	u32 regulator_count;
 	struct regulator **regulators;
 #endif
@@ -208,12 +210,12 @@ struct simplefb_par {
  * the fb probe will not help us much either. So just complain and carry on,
  * and hope that the user actually gets a working fb at the end of things.
  */
-static int simplefb_clocks_init(struct simplefb_par *par,
-				struct platform_device *pdev)
+static int simplefb_clocks_get(struct simplefb_par *par,
+			       struct platform_device *pdev)
 {
 	struct device_node *np = pdev->dev.of_node;
 	struct clk *clock;
-	int i, ret;
+	int i;
 
 	if (dev_get_platdata(&pdev->dev) || !np)
 		return 0;
@@ -244,6 +246,14 @@ static int simplefb_clocks_init(struct simplefb_par *par,
 		par->clks[i] = clock;
 	}
 
+	return 0;
+}
+
+static void simplefb_clocks_enable(struct simplefb_par *par,
+				   struct platform_device *pdev)
+{
+	int i, ret;
+
 	for (i = 0; i < par->clk_count; i++) {
 		if (par->clks[i]) {
 			ret = clk_prepare_enable(par->clks[i]);
@@ -256,8 +266,7 @@ static int simplefb_clocks_init(struct simplefb_par *par,
 			}
 		}
 	}
-
-	return 0;
+	par->clks_enabled = true;
 }
 
 static void simplefb_clocks_destroy(struct simplefb_par *par)
@@ -269,7 +278,8 @@ static void simplefb_clocks_destroy(struct simplefb_par *par)
 
 	for (i = 0; i < par->clk_count; i++) {
 		if (par->clks[i]) {
-			clk_disable_unprepare(par->clks[i]);
+			if (par->clks_enabled)
+				clk_disable_unprepare(par->clks[i]);
 			clk_put(par->clks[i]);
 		}
 	}
@@ -277,8 +287,10 @@ static void simplefb_clocks_destroy(struct simplefb_par *par)
 	kfree(par->clks);
 }
 #else
-static int simplefb_clocks_init(struct simplefb_par *par,
+static int simplefb_clocks_get(struct simplefb_par *par,
 	struct platform_device *pdev) { return 0; }
+static void simplefb_clocks_enable(struct simplefb_par *par,
+	struct platform_device *pdev) { }
 static void simplefb_clocks_destroy(struct simplefb_par *par) { }
 #endif
 
@@ -305,14 +317,14 @@ static void simplefb_clocks_destroy(struct simplefb_par *par) { }
  * the fb probe will not help us much either. So just complain and carry on,
  * and hope that the user actually gets a working fb at the end of things.
  */
-static int simplefb_regulators_init(struct simplefb_par *par,
-	struct platform_device *pdev)
+static int simplefb_regulators_get(struct simplefb_par *par,
+				   struct platform_device *pdev)
 {
 	struct device_node *np = pdev->dev.of_node;
 	struct property *prop;
 	struct regulator *regulator;
 	const char *p;
-	int count = 0, i = 0, ret;
+	int count = 0, i = 0;
 
 	if (dev_get_platdata(&pdev->dev) || !np)
 		return 0;
@@ -354,6 +366,14 @@ static int simplefb_regulators_init(struct simplefb_par *par,
 	}
 	par->regulator_count = i;
 
+	return 0;
+}
+
+static void simplefb_regulators_enable(struct simplefb_par *par,
+				       struct platform_device *pdev)
+{
+	int i, ret;
+
 	/* Enable all the regulators */
 	for (i = 0; i < par->regulator_count; i++) {
 		ret = regulator_enable(par->regulators[i]);
@@ -365,15 +385,14 @@ static int simplefb_regulators_init(struct simplefb_par *par,
 			par->regulators[i] = NULL;
 		}
 	}
-
-	return 0;
+	par->regulators_enabled = true;
 }
 
 static void simplefb_regulators_destroy(struct simplefb_par *par)
 {
 	int i;
 
-	if (!par->regulators)
+	if (!par->regulators || !par->regulators_enabled)
 		return;
 
 	for (i = 0; i < par->regulator_count; i++)
@@ -381,8 +400,10 @@ static void simplefb_regulators_destroy(struct simplefb_par *par)
 			regulator_disable(par->regulators[i]);
 }
 #else
-static int simplefb_regulators_init(struct simplefb_par *par,
+static int simplefb_regulators_get(struct simplefb_par *par,
 	struct platform_device *pdev) { return 0; }
+static void simplefb_regulators_enable(struct simplefb_par *par,
+	struct platform_device *pdev) { }
 static void simplefb_regulators_destroy(struct simplefb_par *par) { }
 #endif
 
@@ -453,14 +474,17 @@ static int simplefb_probe(struct platform_device *pdev)
 	}
 	info->pseudo_palette = par->palette;
 
-	ret = simplefb_clocks_init(par, pdev);
+	ret = simplefb_clocks_get(par, pdev);
 	if (ret < 0)
 		goto error_unmap;
 
-	ret = simplefb_regulators_init(par, pdev);
+	ret = simplefb_regulators_get(par, pdev);
 	if (ret < 0)
 		goto error_clocks;
 
+	simplefb_clocks_enable(par, pdev);
+	simplefb_regulators_enable(par, pdev);
+
 	dev_info(&pdev->dev, "framebuffer at 0x%lx, 0x%x bytes, mapped to 0x%p\n",
 			     info->fix.smem_start, info->fix.smem_len,
 			     info->screen_base);
-- 
2.9.3