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authorKalle Jokiniemi2010-05-11 11:35:08 -0700
committerBen Dooks2010-05-20 00:18:59 +0100
commit20c9d2c4ab8243a1c311248232954b2c1da3ba75 (patch)
treee035de70d7b89618bb0e6923272849df7d1acb9a /drivers/i2c
parentf38e66e0077659e5d2ca3858fdb26fc9b1765b9f (diff)
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. Updates by Kevin as requested by Tony: - Remove omap_set_i2c_constraint_func() in favor of conditionally adding the flag in omap_i2c_add_bus() in order to keep all the OMAP conditional checking in a single location. - Update set_mpu_wkup_lat prototypes to match OMAP PM layer so OMAP PM function can be used directly in pdata. Cc: Moiz Sonasath <m-sonasath@ti.com> Cc: Jarkko Nikula <jhnikula@gmail.com> Cc: Paul Walmsley <paul@pwsan.com> Cc: Nishanth Menon <nm@ti.com> Signed-off-by: Kalle Jokiniemi <kalle.jokiniemi@digia.com> Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com> Signed-off-by: Tony Lindgren <tony@atomide.com> Signed-off-by: Ben Dooks <ben-linux@fluff.org>
Diffstat (limited to 'drivers/i2c')
-rw-r--r--drivers/i2c/busses/i2c-omap.c24
1 files changed, 20 insertions, 4 deletions
diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c
index 46111ff18133..42c0b9108c7f 100644
--- a/drivers/i2c/busses/i2c-omap.c
+++ b/drivers/i2c/busses/i2c-omap.c
@@ -38,6 +38,7 @@
#include <linux/clk.h>
#include <linux/io.h>
#include <linux/slab.h>
+#include <linux/i2c-omap.h>
/* I2C controller revisions */
#define OMAP_I2C_REV_2 0x20
@@ -175,6 +176,9 @@ 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,
+ long latency);
u32 speed; /* Speed of bus in Khz */
u16 cmd_err;
u8 *buf;
@@ -603,8 +607,12 @@ 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;
@@ -927,6 +935,7 @@ 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;
@@ -956,10 +965,13 @@ 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 */