Re: [PATCH v3 2/7] i2c: bcm2835: Protect against unexpected TXW/RXR interrupts

[Noralf TrÃnnes]

Den 29.09.2016 00:00, skrev Eric Anholt:
> Noralf TrÃnnes <noralf@xxxxxxxxxxx> writes:
>
> > If an unexpected TXW or RXR interrupt occurs (msg_buf_remaining == 0),
> > the driver has no way to fill/drain the FIFO to stop the interrupts.
> > In this case the controller has to be disabled and the transfer
> > completed to avoid hang.
> >
> > (CLKT | ERR) and DONE interrupts are completed in their own paths, and
> > the controller is disabled in the transfer function after completion.
> > Unite the code paths and do disabling inside the interrupt routine.
> >
> > Clear interrupt status bits in the united completion path instead of
> > trying to do it on every interrupt which isn't necessary.
> > Only CLKT, ERR and DONE can be cleared that way.
> >
> > Add the status value to the error value in case of TXW/RXR errors to
> > distinguish them from the other S_LEN error.
> I was surprised that not writing the TXW/RXR bits on handling their
> interrupts was OK, given that we were doing so before, but it's a level
> interrupt and those bits are basically ignored on write.
>
> This patch and 3, 4, and 6 are:
>
> Reviewed-by: Eric Anholt <eric@xxxxxxxxxx>
>
> Patch 5 is:
>
> Acked-by: Eric Anholt <eric@xxxxxxxxxx>
>
> Note for future debug: The I2C_C_CLEAR on errors will take some time to
> resolve -- if you were in non-idle state and I2C_C_READ, it sets an
> abort_rx flag and runs through the state machine to send a NACK and a
> STOP, I think.  Since we're setting CLEAR without I2CEN, that NACK will
> be hanging around queued up for next time we start the engine.

Maybe you're able to explain the issues I had with reset:
https://github.com/raspberrypi/linux/issues/1653

Should we put your note into the commit message?
It will most likely be lost if it just stays in this email.

Noralf.