RE: [PATCH v10] i2c: designware: fix controller is holding SCL low while ENABLE bit is disabled

[Liu Kimriver/刘金河]

> -----Original Message-----
> From: Andi Shyti <andi.shyti@xxxxxxxxxx> 
> Sent: 2024年9月13日 0:36
> To: Andy Shevchenko <andy.shevchenko@xxxxxxxxx>
> Cc: Liu Kimriver/刘金河 <kimriver.liu@xxxxxxxxxxxx>; jarkko.nikula@xxxxxxxxxxxxxxx; andriy.shevchenko@xxxxxxxxxxxxxxx; mika.westerberg@xxxxxxxxxxxxxxx; jsd@xxxxxxxxxxxx; linux-i2c@xxxxxxxxxxxxxxx; linux-> kernel@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH v10] i2c: designware: fix controller is holding SCL low while ENABLE bit is disabled

> On Thu, Sep 12, 2024 at 06:32:48PM GMT, Andy Shevchenko wrote:
> > Thu, Sep 12, 2024 at 02:11:12PM +0800, Kimriver Liu kirjoitti:
> > > It was observed that issuing ABORT bit (IC_ENABLE[1]) will not work 
> > > when IC_ENABLE is already disabled.
> > > 
> > > Check if ENABLE bit (IC_ENABLE[0]) is disabled when the controller 
> > > is holding SCL low. If ENABLE bit is disabled, the software need

> /need/needs/

> > > to enable it before trying to issue ABORT bit. otherwise,

> /ABORT/the ABORT/

> > > the controller ignores any write to ABORT bit.
>>  > 
>>  > These kernel logs show up whenever an I2C transaction is attempted 
>>  > after this failure.
>>  > i2c_designware e95e0000.i2c: timeout waiting for bus ready 
>>  > i2c_designware e95e0000.i2c: timeout in disabling adapter
> > 
>>  > The patch can be fix the controller cannot be disabled while SCL is 
>>  > held low in ENABLE bit is already disabled.
>>  
> > There are English words but a complete nonsense together.

> We could reword this to:

> The patch fixes the issue where the controller cannot be disabled while SCL is held low if the ENABLE bit is already disabled.

> >   Fix the condition when controller cannot be disabled while SCL

> /when/where/

> >   is held low and ENABLE bit is already disabled.

> /ENABLE/the ENABLE/

> If you agree with the changes, I can apply them before merging.

> > 
> > Reviewed-by: Andy Shevchenko <andy@xxxxxxxxxx>

> Thanks a lot, Andy! I really appreciate your reviews!

> > ...
> > 
> > > +		if (!(enable & DW_IC_ENABLE_ENABLE)) {
> > > +			regmap_write(dev->map, DW_IC_ENABLE, DW_IC_ENABLE_ENABLE);
> > > +			/*
>> > +			 * Wait 10 times the signaling period of the highest I2C
>> > +			 * transfer supported by the driver (for 400KHz this is
> > > +			 * 25us) to ensure the I2C ENABLE bit is already set
> > > +			 * as described in the DesignWare I2C databook.
> > > +			 */
> > > +			fsleep(DIV_ROUND_CLOSEST_ULL(10 * MICRO, t->bus_freq_hz));
> > 
> > > +			/* Keep ENABLE bit is already set before Setting ABORT.*/
>>  
>>  			/* Set ENABLE bit before setting ABORT */
>>  
>>  
>> > +			enable |= DW_IC_ENABLE_ENABLE;
>> > +		}
> > 
>>
> > 
> > > +/*
> > > + * This functions waits controller idling before disabling I2C
> > 
> > s/functions/function/

> I can fix it before merging.

OK，I agree with your fixing it before merging. Thanks for your review!

> > > + * When the controller is not in the IDLE state,
> > > + * MST_ACTIVITY bit (IC_STATUS[5]) is set.
> > > + * Values:
> > > + * 0x1 (ACTIVE): Controller not idle
>>  > + * 0x0 (IDLE): Controller is idle
>>  > + * The function is called after returning the end of the current 
>>  > +transfer
>>  > + * Returns:
> > > + * False when controller is in IDLE state.
>>  > + * True when controller is in ACTIVE state.
> > > + */
> > > +static bool i2c_dw_is_controller_active(struct dw_i2c_dev *dev) {
> > > +	u32 status;
> > > +
>>  > +	regmap_read(dev->map, DW_IC_STATUS, &status);
> > > +	if (!(status & DW_IC_STATUS_MASTER_ACTIVITY))
> > > +		return false;
>>  > +
>>  > +	return regmap_read_poll_timeout(dev->map, DW_IC_STATUS, status,
>>  > +				       !(status & DW_IC_STATUS_MASTER_ACTIVITY),
>>  > +					1100, 20000) != 0;
> > 
> > 	return regmap_read_poll_timeout(dev->map, DW_IC_STATUS, status,
>>  					!(status & DW_IC_STATUS_MASTER_ACTIVITY),
> > 					1100, 20000) != 0;
> 
> > (in the second line replaced 7 spaces by a single TAB to fix the 
>>  indentation)

> I can fix it before merging.

> Kimriver, if you agree, i can merge this and queue it for the next week's fixes merge request.
>Andi

 OK，I agree. 
  Do I still need to update to patch V11? Or you fix it before merging

 Thanks for taking the time to review the patch,  I have learned a lot of knowledge .

> > +}
> 
> ...
> 
> > +	/*
> > +	 * This happens rarely (~1:500) and is hard to reproduce. Debug trace
> > +	 * showed that IC_STATUS had value of 0x23 when STOP_DET occurred,
> > +	 * if disable IC_ENABLE.ENABLE immediately that can result in
> > +	 * IC_RAW_INTR_STAT.MASTER_ON_HOLD holding SCL low. Check if
> > +	 * controller is still ACTIVE before disabling I2C.
> > +	 */
> > +	if (i2c_dw_is_controller_active(dev))
> > +		dev_err(dev->dev, "controller active\n");
> 
> --
> With Best Regards,
> Andy Shevchenko
> 
> 

------------------------------------------
Best Regards
Kimriver Liu