While waiting for completion of the i2c transfer, the
MPU could hit OFF mode and cause several msecs of
delay that made i2c transfers fail more often. The
extra delays and subsequent re-trys cause i2c clocks
to be active more often. This has also an negative
effect on power consumption.
Added a constraint that allows MPU to wake up in few
hundred usecs, which is roughly the average i2c wait
period.
The constraint function is passed as platform data from
plat-omap/i2c.c and applied only on OMAP34XX devices.
Signed-off-by: Kalle Jokiniemi <kalle.jokiniemi@xxxxxxxxx>
---
arch/arm/plat-omap/i2c.c | 49 +++++++++++++++++++++++++++++++----------
drivers/i2c/busses/i2c-omap.c | 17 +++++++++++---
include/linux/i2c-omap.h | 9 +++++++
3 files changed, 59 insertions(+), 16 deletions(-)
create mode 100644 include/linux/i2c-omap.h
diff --git a/arch/arm/plat-omap/i2c.c b/arch/arm/plat-omap/i2c.c
index 8b84839..d43d0ad 100644
--- a/arch/arm/plat-omap/i2c.c
+++ b/arch/arm/plat-omap/i2c.c
@@ -26,8 +26,10 @@
#include <linux/kernel.h>
#include <linux/platform_device.h>
#include <linux/i2c.h>
+#include <linux/i2c-omap.h>
#include <mach/irqs.h>
#include <mach/mux.h>
+#include <mach/omap-pm.h>
#define OMAP_I2C_SIZE 0x3f
#define OMAP1_I2C_BASE 0xfffb3800
@@ -69,14 +71,14 @@ static struct resource i2c_resources[][2] = {
}, \
}
-static u32 i2c_rate[ARRAY_SIZE(i2c_resources)];
+static struct omap_i2c_bus_platform_data i2c_pdata[ARRAY_SIZE(i2c_resources)];
static struct platform_device omap_i2c_devices[] = {
- I2C_DEV_BUILDER(1, i2c_resources[0], &i2c_rate[0]),
+ I2C_DEV_BUILDER(1, i2c_resources[0], &i2c_pdata[0]),
#if defined(CONFIG_ARCH_OMAP24XX) || defined(CONFIG_ARCH_OMAP34XX)
- I2C_DEV_BUILDER(2, i2c_resources[1], &i2c_rate[1]),
+ I2C_DEV_BUILDER(2, i2c_resources[1], &i2c_pdata[1]),
#endif
#if defined(CONFIG_ARCH_OMAP34XX)
- I2C_DEV_BUILDER(3, i2c_resources[2], &i2c_rate[2]),
+ I2C_DEV_BUILDER(3, i2c_resources[2], &i2c_pdata[2]),
#endif
};
@@ -100,6 +102,25 @@ static const int omap34xx_pins[][2] = {};
#define OMAP_I2C_CMDLINE_SETUP (BIT(31))
+/**
+ * omap_i2c_set_wfc_mpu_wkup_lat - sets mpu wake up constraint
+ * @dev: i2c bus device pointer
+ * @set: set or clear constraints
+ *
+ * When waiting for completion of a i2c transfer, we need to set a wake up
+ * latency constraint for the MPU. This is to ensure quick enough wakeup
+ * from idle, when transfer completes.
+ */
+#ifdef CONFIG_ARCH_OMAP34XX
+static void omap_i2c_set_wfc_mpu_wkup_lat(struct device *dev, int set)
+{
+ omap_pm_set_max_mpu_wakeup_lat(dev, set ? 500 : -1);
+}
+#else
+static inline void omap_i2c_set_wfc_mpu_wkup_lat(struct device *dev, int set)
+{; }
+#endif
+
static void __init omap_i2c_mux_pins(int bus)
{
int scl, sda;
@@ -180,8 +201,8 @@ static int __init omap_i2c_bus_setup(char *str)
get_options(str, 3, ints);
if (ints[0] < 2 || ints[1] < 1 || ints[1] > ports)
return 0;
- i2c_rate[ints[1] - 1] = ints[2];
- i2c_rate[ints[1] - 1] |= OMAP_I2C_CMDLINE_SETUP;
+ i2c_pdata[ints[1] - 1].clkrate = ints[2];
+ i2c_pdata[ints[1] - 1].clkrate |= OMAP_I2C_CMDLINE_SETUP;
return 1;
}
@@ -195,9 +216,11 @@ static int __init omap_register_i2c_bus_cmdline(void)
{
int i, err = 0;
- for (i = 0; i < ARRAY_SIZE(i2c_rate); i++)
- if (i2c_rate[i] & OMAP_I2C_CMDLINE_SETUP) {
- i2c_rate[i] &= ~OMAP_I2C_CMDLINE_SETUP;
+ for (i = 0; i < ARRAY_SIZE(i2c_pdata); i++)
+ if (i2c_pdata[i].clkrate & OMAP_I2C_CMDLINE_SETUP) {
+ i2c_pdata[i].clkrate &= ~OMAP_I2C_CMDLINE_SETUP;
+ i2c_pdata[i].set_mpu_wkup_lat =
+ omap_i2c_set_wfc_mpu_wkup_lat;
err = omap_i2c_add_bus(i + 1);
if (err)
goto out;
@@ -231,9 +254,11 @@ int __init omap_register_i2c_bus(int bus_id, u32 clkrate,
return err;
}
- if (!i2c_rate[bus_id - 1])
- i2c_rate[bus_id - 1] = clkrate;
- i2c_rate[bus_id - 1] &= ~OMAP_I2C_CMDLINE_SETUP;
+ if (!i2c_pdata[bus_id - 1].clkrate)
+ i2c_pdata[bus_id - 1].clkrate = clkrate;
+
+ i2c_pdata[bus_id - 1].set_mpu_wkup_lat = omap_i2c_set_wfc_mpu_wkup_lat;
+ i2c_pdata[bus_id - 1].clkrate &= ~OMAP_I2C_CMDLINE_SETUP;
return omap_i2c_add_bus(bus_id);
}
diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c
index 75bf3ad..da6d276 100644
--- a/drivers/i2c/busses/i2c-omap.c
+++ b/drivers/i2c/busses/i2c-omap.c
@@ -37,6 +37,7 @@
#include <linux/platform_device.h>
#include <linux/clk.h>
#include <linux/io.h>
+#include <linux/i2c-omap.h>
/* I2C controller revisions */
#define OMAP_I2C_REV_2 0x20
@@ -165,6 +166,8 @@ struct omap_i2c_dev {
struct clk *fclk; /* Functional clock */
struct completion cmd_complete;
struct resource *ioarea;
+ void (*set_mpu_wkup_lat)(struct device *dev,
+ int set);
u32 speed; /* Speed of bus in Khz */
u16 cmd_err;
u8 *buf;
@@ -526,8 +529,10 @@ static int omap_i2c_xfer_msg(struct i2c_adapter *adap,
* REVISIT: We should abort the transfer on signals, but the bus goes
* into arbitration and we're currently unable to recover from it.
*/
+ dev->set_mpu_wkup_lat(dev->dev, 1);
r = wait_for_completion_timeout(&dev->cmd_complete,
OMAP_I2C_TIMEOUT);
+ dev->set_mpu_wkup_lat(dev->dev, 0);
dev->buf_len = 0;
if (r < 0)
return r;
@@ -844,6 +849,7 @@ omap_i2c_probe(struct platform_device *pdev)
struct omap_i2c_dev *dev;
struct i2c_adapter *adap;
struct resource *mem, *irq, *ioarea;
+ struct omap_i2c_bus_platform_data *pdata = pdev->dev.platform_data;
irq_handler_t isr;
int r;
u32 speed = 0;
@@ -873,10 +879,13 @@ omap_i2c_probe(struct platform_device *pdev)
goto err_release_region;
}
- if (pdev->dev.platform_data != NULL)
- speed = *(u32 *)pdev->dev.platform_data;
- else
- speed = 100; /* Defualt speed */
+ if (pdata != NULL) {
+ speed = pdata->clkrate;
+ dev->set_mpu_wkup_lat = pdata->set_mpu_wkup_lat;
+ } else {
+ speed = 100; /* Default speed */
+ dev->set_mpu_wkup_lat = NULL;
+ }
dev->speed = speed;
dev->idle = 1;
diff --git a/include/linux/i2c-omap.h b/include/linux/i2c-omap.h
new file mode 100644
index 0000000..1362fba
--- /dev/null
+++ b/include/linux/i2c-omap.h
@@ -0,0 +1,9 @@
+#ifndef __I2C_OMAP_H__
+#define __I2C_OMAP_H__
+
+struct omap_i2c_bus_platform_data {
+ u32 clkrate;
+ void (*set_mpu_wkup_lat)(struct device *dev, int set);
+};
+
+#endif
--
1.5.4.3
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