Tony Lindgren <tony@xxxxxxxxxxx> writes:
[...]
>>
>> Here's another one to add to omap-testing then.
>>
>> This one has been submitted to linux-i2c a couple times and been in
>> the OMAP PM branch for a while.
>
> OK, let's add that to omap-testing after we're done with the initial
> fixes. This does not currently apply on top of omap-testing, BTW.
Here's an updated version that applies on omap-testing.
Kevin
>From 5e5fcf4322b04e27698f1ae48d12ae788969ea49 Mon Sep 17 00:00:00 2001
From: Kalle Jokiniemi <kalle.jokiniemi@xxxxxxxxx>
Date: Wed, 21 Oct 2009 14:51:21 +0300
Subject: [PATCH] i2c-omap: add mpu wake up latency constraint in i2c
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.
Created a mechanism for passing and using the
constraint setting function in driver code. The used
mpu wake up latency constraints are now set individually
per bus, and they are calculated based on clock rate
and fifo size.
Thanks to Jarkko Nikula, Moiz Sonasath, Paul Walmsley,
and Nishanth Menon for tuning out the details of
this patch.
Cc: Moiz Sonasath <m-sonasath@xxxxxx>
Cc: Jarkko Nikula <jhnikula@xxxxxxxxx>
Cc: Paul Walmsley <paul@xxxxxxxxx>
Cc: Nishanth Menon <nm@xxxxxx>
Signed-off-by: Kalle Jokiniemi <kalle.jokiniemi@xxxxxxxxx>
Signed-off-by: Kevin Hilman <khilman@xxxxxxxxxxxxxxxxxxx>
---
arch/arm/plat-omap/i2c.c | 55 ++++++++++++++++++++++++++++++++---------
drivers/i2c/busses/i2c-omap.c | 24 +++++++++++++++---
include/linux/i2c-omap.h | 9 ++++++
3 files changed, 72 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 624e262..36011a1 100644
--- a/arch/arm/plat-omap/i2c.c
+++ b/arch/arm/plat-omap/i2c.c
@@ -26,9 +26,12 @@
#include <linux/kernel.h>
#include <linux/platform_device.h>
#include <linux/i2c.h>
+#include <linux/i2c-omap.h>
+
#include <mach/irqs.h>
#include <plat/mux.h>
#include <plat/i2c.h>
+#include <plat/omap-pm.h>
#define OMAP_I2C_SIZE 0x3f
#define OMAP1_I2C_BASE 0xfffb3800
@@ -70,19 +73,44 @@ 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_OMAP2) || defined(CONFIG_ARCH_OMAP3)
- 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_OMAP3)
- I2C_DEV_BUILDER(3, i2c_resources[2], &i2c_rate[2]),
+ I2C_DEV_BUILDER(3, i2c_resources[2], &i2c_pdata[2]),
#endif
};
#define OMAP_I2C_CMDLINE_SETUP (BIT(31))
+#ifdef CONFIG_ARCH_OMAP3
+/*
+ * omap_i2c_set_wfc_mpu_wkup_lat - sets mpu wake up constraint
+ * @dev: i2c bus device pointer
+ * @val: latency constraint to set, -1 to disable constraint
+ *
+ * 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.
+ */
+static void omap_i2c_set_wfc_mpu_wkup_lat(struct device *dev, int val)
+{
+ omap_pm_set_max_mpu_wakeup_lat(dev, val);
+}
+#endif
+
+static void __init omap_set_i2c_constraint_func(
+ struct omap_i2c_bus_platform_data *pd)
+{
+ if (cpu_is_omap34xx())
+ pd->set_mpu_wkup_lat = omap_i2c_set_wfc_mpu_wkup_lat;
+ else
+ pd->set_mpu_wkup_lat = NULL;
+}
+
static int __init omap_i2c_nr_ports(void)
{
int ports = 0;
@@ -146,8 +174,8 @@ 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;
}
@@ -161,9 +189,10 @@ 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;
+ omap_set_i2c_constraint_func(&i2c_pdata[i]);
err = omap_i2c_add_bus(i + 1);
if (err)
goto out;
@@ -197,9 +226,11 @@ 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;
+
+ omap_set_i2c_constraint_func(&i2c_pdata[bus_id - 1]);
+ 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 f2019d2..7a80b00 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
@@ -174,6 +175,9 @@ struct omap_i2c_dev {
struct clk *fclk; /* Functional clock */
struct completion cmd_complete;
struct resource *ioarea;
+ u32 latency; /* maximum mpu wkup latency */
+ void (*set_mpu_wkup_lat)(struct device *dev,
+ int latency);
u32 speed; /* Speed of bus in Khz */
u16 cmd_err;
u8 *buf;
@@ -602,8 +606,12 @@ 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.
*/
+ if (dev->set_mpu_wkup_lat != NULL)
+ dev->set_mpu_wkup_lat(dev->dev, dev->latency);
r = wait_for_completion_timeout(&dev->cmd_complete,
OMAP_I2C_TIMEOUT);
+ if (dev->set_mpu_wkup_lat != NULL)
+ dev->set_mpu_wkup_lat(dev->dev, -1);
dev->buf_len = 0;
if (r < 0)
return r;
@@ -926,6 +934,7 @@ 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;
@@ -955,10 +964,13 @@ 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;
@@ -1011,6 +1023,10 @@ omap_i2c_probe(struct platform_device *pdev)
dev->fifo_size = (dev->fifo_size / 2);
dev->b_hw = 1; /* Enable hardware fixes */
}
+ /* calculate wakeup latency constraint for MPU */
+ if (dev->set_mpu_wkup_lat != NULL)
+ dev->latency = (1000000 * dev->fifo_size) /
+ (1000 * speed / 8);
}
/* reset ASAP, clearing any IRQs */
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
--
1.7.0.2
--
To unsubscribe from this list: send the line "unsubscribe linux-i2c" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
