Philby John <pjohn@xxxxxxxxxxxxx> writes: > On Sun, 2010-01-24 at 15:07 +0000, Ben Dooks wrote: >> On Tue, Jan 12, 2010 at 04:47:16PM +0530, Philby John wrote: >> > >From 2565eeda807e49376298ec895a0d9a91a7668417 Mon Sep 17 00:00:00 2001 >> > From: Philby John <pjohn@xxxxxxxxxxxxx> >> > Date: Mon, 11 Jan 2010 22:39:44 +0530 >> > Subject: [PATCH 2/2] Davinci i2c bus recovery procedure to clear the bus >> > >> > Come out of i2c time out condition by following the >> > bus recovery procedure outlined in the i2c protocol v3 spec. >> > The kernel must be robust enough to gracefully recover >> > from i2c bus failure without having to reset the machine. >> > This is done by first NACKing the slave, pulsing the SCL >> > line 9 times and then sending the stop command. >> > >> > This patch has been tested on a DM6446 and DM355 >> >> Still not sure whether this can be included as a bug-fix or whether >> it comes under the new feature category. Also, since it has to get >> new data from the platform whose tree it should really go into. > > This fix is for the issue that was reported here > http://www.mail-archive.com/davinci-linux-open-source@xxxxxxxxxxxxxxxxxxxx/msg13560.html which IMHO is critical. The issue can be replicated easily and without it the user is left with no choice but to reset the target. > > Yes, it does depend on [PATCH 1/2] for platform dependent data, would > fail otherwise. Could you suggest what may I do in this circumstances? This patch looks OK to me, and I'm happy to merge it via DaVinci git for 2.6.34 since it has a compile dependency with PATCH 1/1. Ben, if you're OK with that, can I have your Ack and I can merge it? Thanks, Kevin > >> >> > Signed-off-by: Philby John <pjohn@xxxxxxxxxxxxx> >> > Signed-off-by: Srinivasan, Nageswari <nageswari@xxxxxx> >> > --- >> > drivers/i2c/busses/i2c-davinci.c | 57 +++++++++++++++++++++++++++++++++++-- >> > 1 files changed, 53 insertions(+), 4 deletions(-) >> > >> > diff --git a/drivers/i2c/busses/i2c-davinci.c b/drivers/i2c/busses/i2c-davinci.c >> > index 35f9daa..5459065 100644 >> > --- a/drivers/i2c/busses/i2c-davinci.c >> > +++ b/drivers/i2c/busses/i2c-davinci.c >> > @@ -36,6 +36,7 @@ >> > #include <linux/platform_device.h> >> > #include <linux/io.h> >> > #include <linux/cpufreq.h> >> > +#include <linux/gpio.h> >> > >> > #include <mach/hardware.h> >> > #include <mach/i2c.h> >> > @@ -43,6 +44,7 @@ >> > /* ----- global defines ----------------------------------------------- */ >> > >> > #define DAVINCI_I2C_TIMEOUT (1*HZ) >> > +#define DAVINCI_I2C_MAX_TRIES 2 >> > #define I2C_DAVINCI_INTR_ALL (DAVINCI_I2C_IMR_AAS | \ >> > DAVINCI_I2C_IMR_SCD | \ >> > DAVINCI_I2C_IMR_ARDY | \ >> > @@ -130,6 +132,44 @@ static inline u16 davinci_i2c_read_reg(struct davinci_i2c_dev *i2c_dev, int reg) >> > return __raw_readw(i2c_dev->base + reg); >> > } >> > >> > +/* Generate a pulse on the i2c clock pin. */ >> > +static void generic_i2c_clock_pulse(unsigned int scl_pin) >> > +{ >> > + u16 i; >> > + >> > + if (scl_pin) { >> > + /* Send high and low on the SCL line */ >> > + for (i = 0; i < 9; i++) { >> > + gpio_set_value(scl_pin, 0); >> > + udelay(20); >> > + gpio_set_value(scl_pin, 1); >> > + udelay(20); >> > + } >> > + } >> > +} >> > + >> > +/* This routine does i2c bus recovery as specified in the >> > + * i2c protocol Rev. 03 section 3.16 titled "Bus clear" >> > + */ >> > +static void i2c_recover_bus(struct davinci_i2c_dev *dev) >> > +{ >> > + u32 flag = 0; >> > + struct davinci_i2c_platform_data *pdata = dev->dev->platform_data; >> > + >> > + dev_err(dev->dev, "initiating i2c bus recovery\n"); >> > + /* Send NACK to the slave */ >> > + flag = davinci_i2c_read_reg(dev, DAVINCI_I2C_MDR_REG); >> > + flag |= DAVINCI_I2C_MDR_NACK; >> > + /* write the data into mode register */ >> > + davinci_i2c_write_reg(dev, DAVINCI_I2C_MDR_REG, flag); >> > + if (pdata) >> > + generic_i2c_clock_pulse(pdata->scl_pin); >> > + /* Send STOP */ >> > + flag = davinci_i2c_read_reg(dev, DAVINCI_I2C_MDR_REG); >> > + flag |= DAVINCI_I2C_MDR_STP; >> > + davinci_i2c_write_reg(dev, DAVINCI_I2C_MDR_REG, flag); >> > +} >> > + >> > static inline void davinci_i2c_reset_ctrl(struct davinci_i2c_dev *i2c_dev, >> > int val) >> > { >> > @@ -235,14 +275,22 @@ static int i2c_davinci_wait_bus_not_busy(struct davinci_i2c_dev *dev, >> > char allow_sleep) >> > { >> > unsigned long timeout; >> > + static u16 to_cnt; >> > >> > timeout = jiffies + dev->adapter.timeout; >> > while (davinci_i2c_read_reg(dev, DAVINCI_I2C_STR_REG) >> > & DAVINCI_I2C_STR_BB) { >> > - if (time_after(jiffies, timeout)) { >> > - dev_warn(dev->dev, >> > - "timeout waiting for bus ready\n"); >> > - return -ETIMEDOUT; >> > + if (to_cnt <= DAVINCI_I2C_MAX_TRIES) { >> > + if (time_after(jiffies, timeout)) { >> > + dev_warn(dev->dev, >> > + "timeout waiting for bus ready\n"); >> > + to_cnt++; >> > + return -ETIMEDOUT; >> > + } else { >> > + to_cnt = 0; >> > + i2c_recover_bus(dev); >> > + i2c_davinci_init(dev); >> > + } >> > } >> > if (allow_sleep) >> > schedule_timeout(1); >> > @@ -324,6 +372,7 @@ i2c_davinci_xfer_msg(struct i2c_adapter *adap, struct i2c_msg *msg, int stop) >> > dev->adapter.timeout); >> > if (r == 0) { >> > dev_err(dev->dev, "controller timed out\n"); >> > + i2c_recover_bus(dev); >> > i2c_davinci_init(dev); >> > dev->buf_len = 0; >> > return -ETIMEDOUT; >> > -- >> > 1.6.3.3.MVISTA >> > >> > >> > >> > -- >> > 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 >> > > _______________________________________________ > Davinci-linux-open-source mailing list > Davinci-linux-open-source@xxxxxxxxxxxxxxxxxxxx > http://linux.davincidsp.com/mailman/listinfo/davinci-linux-open-source -- 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
