Kalle Jokiniemi <[email protected]> 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. 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 <[email protected]> > --- > 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 -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
