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Message-ID: <1302485262-8401-1-git-send-email-jiri.pinkava@vscht.cz>
Date: Mon, 11 Apr 2011 03:27:42 +0200
From: Jiri Pinkava <jiri.pinkava@...ht.cz>
To: <ben-linux@...ff.org>
CC: <kgene.kim@...sung.com>, <dwmw2@...radead.org>,
<linux-arm-kernel@...ts.infradead.org>,
<linux-mtd@...ts.infradead.org>, <linux-kernel@...r.kernel.org>,
Jiri Pinkava <jiri.pinkava@...ht.cz>
Subject: [PATCH] nand: Fix S3C NAND clock stop
Current implementation of s3c2410_nand_select_chip call
clk_disable every time when chip = -1 (de-select). This happend
multiple times even if chip was already de-selected. This causes
disabling clock even if they are already disabled and due to
nature of clock subsytem implementation this causes nand clock
to be disabled and newer enabled again.
Signed-off-by: Jiri Pinkava <jiri.pinkava@...ht.cz>
---
drivers/mtd/nand/s3c2410.c | 57 +++++++++++++++++++++++++++++++------------
1 files changed, 41 insertions(+), 16 deletions(-)
diff --git a/drivers/mtd/nand/s3c2410.c b/drivers/mtd/nand/s3c2410.c
index 33d832d..79e18a3 100644
--- a/drivers/mtd/nand/s3c2410.c
+++ b/drivers/mtd/nand/s3c2410.c
@@ -54,8 +54,14 @@ static int hardware_ecc = 1;
static int hardware_ecc = 0;
#endif
+#define CLOCK_DISABLE 0
+#define CLOCK_ENABLE 1
+#define CLOCK_SUSPEND 2
+
+static int clock_state = CLOCK_DISABLE;
+
#ifdef CONFIG_MTD_NAND_S3C2410_CLKSTOP
-static int clock_stop = 1;
+static const int clock_stop = 1;
#else
static const int clock_stop = 0;
#endif
@@ -159,11 +165,33 @@ static struct s3c2410_platform_nand *to_nand_plat(struct platform_device *dev)
return dev->dev.platform_data;
}
-static inline int allow_clk_stop(struct s3c2410_nand_info *info)
+static inline int allow_clk_suspend(struct s3c2410_nand_info *info)
{
return clock_stop;
}
+/**
+ * s3c2410_nand_clk_set_state - Enable, disable or suspend NAND clock.
+ * @info: The controller instance.
+ * @state: State to which clock should be set.
+ */
+static void s3c2410_nand_clk_set_state(struct s3c2410_nand_info *info,
+ int new_state)
+{
+ if (!allow_clk_suspend(info) && new_state == CLOCK_SUSPEND)
+ return;
+
+ if (clock_state == CLOCK_ENABLE) {
+ if (new_state != CLOCK_ENABLE)
+ clk_disable(info->clk);
+ } else {
+ if (new_state == CLOCK_ENABLE)
+ clk_enable(info->clk);
+ }
+
+ clock_state = new_state;
+}
+
/* timing calculations */
#define NS_IN_KHZ 1000000
@@ -333,8 +361,8 @@ static void s3c2410_nand_select_chip(struct mtd_info *mtd, int chip)
nmtd = this->priv;
info = nmtd->info;
- if (chip != -1 && allow_clk_stop(info))
- clk_enable(info->clk);
+ if (chip != -1)
+ s3c2410_nand_clk_set_state(info, CLOCK_ENABLE);
cur = readl(info->sel_reg);
@@ -356,8 +384,8 @@ static void s3c2410_nand_select_chip(struct mtd_info *mtd, int chip)
writel(cur, info->sel_reg);
- if (chip == -1 && allow_clk_stop(info))
- clk_disable(info->clk);
+ if (chip == -1)
+ s3c2410_nand_clk_set_state(info, CLOCK_SUSPEND);
}
/* s3c2410_nand_hwcontrol
@@ -694,8 +722,7 @@ static int s3c24xx_nand_remove(struct platform_device *pdev)
/* free the common resources */
if (info->clk != NULL && !IS_ERR(info->clk)) {
- if (!allow_clk_stop(info))
- clk_disable(info->clk);
+ s3c2410_nand_clk_set_state(info, CLOCK_DISABLE);
clk_put(info->clk);
}
@@ -947,7 +974,7 @@ static int s3c24xx_nand_probe(struct platform_device *pdev)
goto exit_error;
}
- clk_enable(info->clk);
+ s3c2410_nand_clk_set_state(info, CLOCK_ENABLE);
/* allocate and map the resource */
@@ -1026,9 +1053,9 @@ static int s3c24xx_nand_probe(struct platform_device *pdev)
goto exit_error;
}
- if (allow_clk_stop(info)) {
+ if (allow_clk_suspend(info)) {
dev_info(&pdev->dev, "clock idle support enabled\n");
- clk_disable(info->clk);
+ s3c2410_nand_clk_set_state(info, CLOCK_SUSPEND);
}
pr_debug("initialised ok\n");
@@ -1059,8 +1086,7 @@ static int s3c24xx_nand_suspend(struct platform_device *dev, pm_message_t pm)
writel(info->save_sel | info->sel_bit, info->sel_reg);
- if (!allow_clk_stop(info))
- clk_disable(info->clk);
+ s3c2410_nand_clk_set_state(info, CLOCK_DISABLE);
}
return 0;
@@ -1072,7 +1098,7 @@ static int s3c24xx_nand_resume(struct platform_device *dev)
unsigned long sel;
if (info) {
- clk_enable(info->clk);
+ s3c2410_nand_clk_set_state(info, CLOCK_ENABLE);
s3c2410_nand_inithw(info);
/* Restore the state of the nFCE line. */
@@ -1082,8 +1108,7 @@ static int s3c24xx_nand_resume(struct platform_device *dev)
sel |= info->save_sel & info->sel_bit;
writel(sel, info->sel_reg);
- if (allow_clk_stop(info))
- clk_disable(info->clk);
+ s3c2410_nand_clk_set_state(info, CLOCK_SUSPEND);
}
return 0;
--
1.7.4.4
--
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