Philby John <pj...@in.mvista.com> 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 <pj...@in.mvista.com>
>> > 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@linux.davincidsp.com/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 <pj...@in.mvista.com>
>> > Signed-off-by: Srinivasan, Nageswari <nagesw...@ti.com>
>> > ---
>> > 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 majord...@vger.kernel.org
>> > More majordomo info at http://vger.kernel.org/majordomo-info.html
>>
>
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