Hi,
Few comments inlined.
Regards,
Chandra
----- Original Message -----
From: ""Högander" Jouni" <jouni.hogander@xxxxxxxxx>
To: "ext Rajendra Nayak" <rnayak@xxxxxx>
Cc: <linux-omap@xxxxxxxxxxxxxxx>
Sent: Thursday, September 11, 2008 3:34 PM
Subject: Re: [PATCH 04/12] I2C re-init for every cmd
"ext Rajendra Nayak" <rnayak@xxxxxx> writes:
This patch does i2c init/re-init for every transfer
Signed-off-by: Rajendra Nayak <rnayak@xxxxxx>
---
drivers/i2c/busses/i2c-omap.c | 2 ++
1 files changed, 2 insertions(+)
Index: linux-omap-2.6/drivers/i2c/busses/i2c-omap.c
===================================================================
--- linux-omap-2.6.orig/drivers/i2c/busses/i2c-omap.c 2008-09-01
18:11:28.000000000 +0530
+++ linux-omap-2.6/drivers/i2c/busses/i2c-omap.c 2008-09-01 18:11:52.000000000
+0530
@@ -496,6 +496,8 @@ omap_i2c_xfer(struct i2c_adapter *adap,
omap_i2c_unidle(dev);
+ omap_i2c_init(dev);
+
if ((r = omap_i2c_wait_for_bb(dev)) < 0)
goto out;
This is causing unacceptable delays on i2c transfers. This is because
occasionally reset loop in init function enters msleep. Is it
necessary to reset i2c controller after off-mode?
Any opinions on this:
diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c
index 3778735..4a27035 100644
--- a/drivers/i2c/busses/i2c-omap.c
+++ b/drivers/i2c/busses/i2c-omap.c
@@ -126,6 +126,14 @@
/* I2C System Configuration Register (OMAP_I2C_SYSC): */
#define OMAP_I2C_SYSC_SRST (1 << 1) /* Soft Reset */
+struct omap3_i2c_regs {
+ u16 sysc;
+ u16 psc;
+ u16 scll;
+ u16 sclh;
+ u16 buf;
+};
+
We can add this as a part of controller structure itself instaed of creating a
new structure. we will store this
psc, scll and others as a part of controller and just restore it. That way we
can do away with omap3_i2c_save_context every time in clk disable.
struct omap_i2c_dev {
struct device *dev;
void __iomem *base; /* virtual */
@@ -147,6 +155,9 @@ struct omap_i2c_dev {
unsigned b_hw:1; /* bad h/w fixes */
unsigned idle:1;
u16 iestate; /* Saved interrupt register */
+#ifdef CONFIG_ARCH_OMAP34XX
+ struct omap3_i2c_regs context;
+#endif
I guess this should work for all the platforms. at least for omap2/3 it should
work w/o any hiccups.
I2C_BUF is the only register which will require cpu check..so while restoring we
can put that check for 2430/34xx.
};
static inline void omap_i2c_write_reg(struct omap_i2c_dev *i2c_dev,
@@ -160,6 +171,26 @@ static inline u16 omap_i2c_read_reg(struct omap_i2c_dev
*i2c_dev, int reg)
return __raw_readw(i2c_dev->base + reg);
}
+#ifdef CONFIG_ARCH_OMAP34XX
+void omap3_i2c_save_context(struct omap_i2c_dev *dev)
+{
+ dev->context.sysc = omap_i2c_read_reg(dev, OMAP_I2C_SYSC_REG);
+ dev->context.psc = omap_i2c_read_reg(dev, OMAP_I2C_PSC_REG);
+ dev->context.scll = omap_i2c_read_reg(dev, OMAP_I2C_SCLL_REG);
+ dev->context.sclh = omap_i2c_read_reg(dev, OMAP_I2C_SCLH_REG);
+ dev->context.buf = omap_i2c_read_reg(dev, OMAP_I2C_BUF_REG);
+}
+
+void omap3_i2c_restore_context(struct omap_i2c_dev *dev)
+{
+ omap_i2c_write_reg(dev, OMAP_I2C_SYSC_REG, dev->context.sysc);
+ omap_i2c_write_reg(dev, OMAP_I2C_PSC_REG, dev->context.psc);
+ omap_i2c_write_reg(dev, OMAP_I2C_SCLL_REG, dev->context.scll);
+ omap_i2c_write_reg(dev, OMAP_I2C_SCLH_REG, dev->context.sclh);
+ omap_i2c_write_reg(dev, OMAP_I2C_BUF_REG, dev->context.buf);
+}
+#endif
+
static int __init omap_i2c_get_clocks(struct omap_i2c_dev *dev)
{
if (cpu_is_omap16xx() || cpu_class_is_omap2()) {
@@ -210,6 +241,10 @@ static void omap_i2c_unidle(struct omap_i2c_dev *dev)
clk_enable(dev->iclk);
clk_enable(dev->fclk);
dev->idle = 0;
+
+ if (cpu_is_omap34xx())
+ omap3_i2c_restore_context(dev);
+
if (dev->iestate)
omap_i2c_write_reg(dev, OMAP_I2C_IE_REG, dev->iestate);
}
@@ -344,6 +379,10 @@ static int omap_i2c_init(struct omap_i2c_dev *dev)
OMAP_I2C_IE_ARDY | OMAP_I2C_IE_NACK |
OMAP_I2C_IE_AL) | ((dev->fifo_size) ?
(OMAP_I2C_IE_RDR | OMAP_I2C_IE_XDR) : 0));
+
+ if (cpu_is_omap34xx())
+ omap3_i2c_save_context(dev);
+
this will become redundant as data will be part of controller structure.
return 0;
}
@@ -496,8 +535,6 @@ omap_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg
msgs[], int num)
omap_i2c_unidle(dev);
- omap_i2c_init(dev);
-
instead of calling restore from clk_enable we can replace omap_i2c_init by
omap3_i2c_restore_context. that way clock enable code will be clean.
if ((r = omap_i2c_wait_for_bb(dev)) < 0)
goto out;
--
Jouni Högander
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