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* [PATCH 04/04] video: Runtime PM hack for SuperH LCDC driver
@ 2009-07-31 14:02 Magnus Damm
  2009-07-31 18:56 ` Rafael J. Wysocki
  0 siblings, 1 reply; 2+ messages in thread
From: Magnus Damm @ 2009-07-31 14:02 UTC (permalink / raw)
  To: linux-sh

From: Magnus Damm <damm@igel.co.jp>

This patch modifies the SuperH Mobile LCDC framebuffer driver
to support Runtime PM. This patch is experimental and is at this
point still missing context save and restore support.

With debug messages it is however already possible to see that
the deferred io clock management strategy pays off since in that
mode the clocks are only turned on for a short period of time to
redraw the screen. When the screen is unchanged the clocks are
disabled and the driver can be in runtime suspended state.

Regarding pm_runtime_put_noidle()/pm_runtime_get_noresume():

This driver does not work well with the Runtime PM v11 code
since it performs runtime_pm_get_sync() from probe() which is
not allowed. This driver needs to access hardware registers from
probe() so runtime_pm_get_sync() must really succeed in this case
so the bus code gets a chance to turn on the hardware device.

Signed-off-by: Magnus Damm <damm@igel.co.jp>
---

 Changes from V1 prototype:
 - use pm_runtime_get_sync() and pm_runtime_put_sync()
 - use pm_runtime_disable()
 - no need for pm_runtime_set_suspended()
 - incomplete runtime pm functions for dev_pm_ops
 - work around with pm_runtime_put_noidle()/pm_runtime_get_noresume()

 TODO:
 - quite a bit

 drivers/video/sh_mobile_lcdcfb.c |   47 +++++++++++++++++++++++---------------
 1 file changed, 29 insertions(+), 18 deletions(-)

--- 0001/drivers/video/sh_mobile_lcdcfb.c
+++ work/drivers/video/sh_mobile_lcdcfb.c	2009-07-30 23:12:49.000000000 +0900
@@ -14,6 +14,7 @@
 #include <linux/mm.h>
 #include <linux/fb.h>
 #include <linux/clk.h>
+#include <linux/pm_runtime.h>
 #include <linux/platform_device.h>
 #include <linux/dma-mapping.h>
 #include <linux/interrupt.h>
@@ -42,9 +43,9 @@ struct sh_mobile_lcdc_chan {
 struct sh_mobile_lcdc_priv {
 	void __iomem *base;
 	int irq;
-	atomic_t clk_usecnt;
+	atomic_t hw_usecnt;
+	struct device *dev;
 	struct clk *dot_clk;
-	struct clk *clk;
 	unsigned long lddckr;
 	struct sh_mobile_lcdc_chan ch[2];
 	int started;
@@ -185,8 +186,8 @@ struct sh_mobile_lcdc_sys_bus_ops sh_mob
 
 static void sh_mobile_lcdc_clk_on(struct sh_mobile_lcdc_priv *priv)
 {
-	if (atomic_inc_and_test(&priv->clk_usecnt)) {
-		clk_enable(priv->clk);
+	if (atomic_inc_and_test(&priv->hw_usecnt)) {
+		pm_runtime_get_sync(priv->dev);
 		if (priv->dot_clk)
 			clk_enable(priv->dot_clk);
 	}
@@ -194,10 +195,10 @@ static void sh_mobile_lcdc_clk_on(struct
 
 static void sh_mobile_lcdc_clk_off(struct sh_mobile_lcdc_priv *priv)
 {
-	if (atomic_sub_return(1, &priv->clk_usecnt) = -1) {
+	if (atomic_sub_return(1, &priv->hw_usecnt) = -1) {
 		if (priv->dot_clk)
 			clk_disable(priv->dot_clk);
-		clk_disable(priv->clk);
+		pm_runtime_put(priv->dev);
 	}
 }
 
@@ -566,7 +567,6 @@ static int sh_mobile_lcdc_setup_clocks(s
 				       int clock_source,
 				       struct sh_mobile_lcdc_priv *priv)
 {
-	char clk_name[8];
 	char *str;
 	int icksel;
 
@@ -580,23 +580,15 @@ static int sh_mobile_lcdc_setup_clocks(s
 
 	priv->lddckr = icksel << 16;
 
-	atomic_set(&priv->clk_usecnt, -1);
-	snprintf(clk_name, sizeof(clk_name), "lcdc%d", pdev->id);
-	priv->clk = clk_get(&pdev->dev, clk_name);
-	if (IS_ERR(priv->clk)) {
-		dev_err(&pdev->dev, "cannot get clock \"%s\"\n", clk_name);
-		return PTR_ERR(priv->clk);
-	}
-
 	if (str) {
 		priv->dot_clk = clk_get(&pdev->dev, str);
 		if (IS_ERR(priv->dot_clk)) {
 			dev_err(&pdev->dev, "cannot get dot clock %s\n", str);
-			clk_put(priv->clk);
 			return PTR_ERR(priv->dot_clk);
 		}
 	}
-
+	atomic_set(&priv->hw_usecnt, -1);
+	pm_runtime_enable(priv->dev);
 	return 0;
 }
 
@@ -714,9 +706,18 @@ static int sh_mobile_lcdc_resume(struct 
 	return sh_mobile_lcdc_start(platform_get_drvdata(pdev));
 }
 
+static int sh_mobile_lcdc_runtime_nop(struct device *dev)
+{
+	/* TODO: implement register save and restore */
+
+	return 0;
+}
+
 static struct dev_pm_ops sh_mobile_lcdc_dev_pm_ops = {
 	.suspend = sh_mobile_lcdc_suspend,
 	.resume = sh_mobile_lcdc_resume,
+	.runtime_suspend = sh_mobile_lcdc_runtime_nop,
+	.runtime_resume = sh_mobile_lcdc_runtime_nop,
 };
 
 static int sh_mobile_lcdc_remove(struct platform_device *pdev);
@@ -753,6 +754,9 @@ static int __init sh_mobile_lcdc_probe(s
 		goto err0;
 	}
 
+	/* workaround: allow resume from probe() */
+	pm_runtime_put_noidle(&pdev->dev);
+
 	error = request_irq(i, sh_mobile_lcdc_irq, IRQF_DISABLED,
 			    dev_name(&pdev->dev), priv);
 	if (error) {
@@ -761,6 +765,7 @@ static int __init sh_mobile_lcdc_probe(s
 	}
 
 	priv->irq = i;
+	priv->dev = &pdev->dev;
 	platform_set_drvdata(pdev, priv);
 	pdata = pdev->dev.platform_data;
 
@@ -896,8 +901,13 @@ static int __init sh_mobile_lcdc_probe(s
 			sh_mobile_lcdc_clk_off(priv);
 	}
 
+	/* workaround: balance pm_runtime_put_noidle() call */
+	pm_runtime_get_noresume(&pdev->dev);
 	return 0;
  err1:
+	/* workaround: balance pm_runtime_put_noidle() call */
+	pm_runtime_get_noresume(&pdev->dev);
+
 	sh_mobile_lcdc_remove(pdev);
  err0:
 	return error;
@@ -932,7 +942,8 @@ static int sh_mobile_lcdc_remove(struct 
 
 	if (priv->dot_clk)
 		clk_put(priv->dot_clk);
-	clk_put(priv->clk);
+
+	pm_runtime_disable(priv->dev);
 
 	if (priv->base)
 		iounmap(priv->base);

^ permalink raw reply	[flat|nested] 2+ messages in thread
end of thread, other threads:[~2009-07-31 18:56 UTC | newest]

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2009-07-31 14:02 [PATCH 04/04] video: Runtime PM hack for SuperH LCDC driver Magnus Damm
2009-07-31 18:56 ` Rafael J. Wysocki

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