On Thu, Aug 23, 2012 at 04:51:41PM +0530, Shubhrajyoti wrote:
> On Thursday 23 August 2012 12:12 AM, Felipe Balbi wrote:
> >> > if (_dev->flags & OMAP_I2C_FLAG_RESET_REGS_POSTIDLE) {
> >> > omap_i2c_write_reg(_dev, OMAP_I2C_CON_REG, 0);
> >> > @@ -1266,6 +1267,15 @@ static int omap_i2c_runtime_resume(struct device *dev)
> >> > omap_i2c_write_reg(_dev, OMAP_I2C_CON_REG, OMAP_I2C_CON_EN);
> >> > }
> >> >
> >> > + while (!(omap_i2c_read_reg(_dev, OMAP_I2C_SYSS_REG) &
> >> > + SYSS_RESETDONE_MASK)) {
> >> > + if (time_after(jiffies, timeout)) {
> >> > + dev_warn(dev, "timeout waiting for controller reset\n");
> >> > + return -ETIMEDOUT;
> >> > + }
> >> > + msleep(1);
> >> > + }
> >> > +
> >> > /*
> >> > * Don't write to this register if the IE state is 0 as it can
> >> > * cause deadlock.
> > That's weird. i2c has SYSS_HAS_RESET_STATUS set, so hwmod framework
> > should be checking that for us. And, in fact, SYSS_HAS_RESET_STATUS is
> > set on all *data.c files.
> Felipe just like writing to sysc reset.
>
> writing
>
> omap_i2c_write_reg(_dev, OMAP_I2C_CON_REG, 0);
>
> [...]
>
> omap_i2c_write_reg(_dev, OMAP_I2C_CON_REG, OMAP_I2C_CON_EN);
>
> is also a reset() and the hwmod is not aware of that.
>
> 1.Hardware reset: A system bus reset (PIRSTNA = 0).
> A device reset causes the system bus reset.
>
> 2. Software reset: A software reset by setting the
> SRST bit in the I2C_SYSC register. This bit has exactly the same
> action on the module logic as the system bus reset.
>
> 3. Partial reset or controller reset. The I2C_EN bit in the I2C_CON
> register can also reset a part of the I^2 C module. When
> the system bus reset is removed (PIRSTNA = 1), I2C_EN = 0 keeps the
> functional part of I^2 C module in reset state and all
> configuration registers can be accessed.
>
>
> Since the case 3 is true in my case I am checking and hwmod is not aware
> of this.
>
> This read-only bit indicates the state of the reset in case of hardware
> reset, global software reset (I2C_SYSC.SRST) or partial software reset
> (I2C_CON.I2C_EN).
>
> I am checking for case 3.
aha, ok. Very nice finding :-) I wasn't aware of that. Maybe that's all
we need then ?? But why only on a few boards ? probably some
timing-related behavior, who knows ;-)
--
balbi
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