On Wed, 2009-09-30 at 19:36 +0300, Kevin Hilman wrote:
> Kalle Jokiniemi <kalle.jokiniemi@xxxxxxxxx> writes:
>
> > 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.
>
> Seems like the latency value should also be (optionally) passed in
> pdata so this can be experimented with per-platform.
Well, it kind of is already, since we pass the function that sets the
latency from platform code. And that function has the latency
hard-coded. My though was to use little #ifdeffery in defining the
function (and latency) for say omap3, and omap4 platforms.
If #ifdeffery is out of the question, we could define
omap3_i2c_set_mpu.. and omap4_i2c_set_mpu.. functions and pass one in
init according to some "if (cpu_is_omapxyz)" statement. I think omap1&2
don't need any latency constraints (and cannot use them as there is no
pm-layer implementation for those).
What do you think?
- Kalle
>
> Other than that looks ok to me.
>
> Do we have an official OMAP I2C maintainer who should signoff on this?
>
> Kevin
>
>
> > 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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