Re: [PATCH 1/3] i2c: imx: Fix reset of I2SR_IAL flag

[Christian Eggers]

Hello Uwe,

On Thursday, 17 September 2020, 16:02:35 CEST, Uwe Kleine-König wrote:
> Hello,
> 
> On Thu, Sep 17, 2020 at 02:20:27PM +0200, Christian Eggers wrote:
> ...
> >  		/* check for arbitration lost */
> >  		if (temp & I2SR_IAL) {
> >  			temp &= ~I2SR_IAL;
> > +			temp |= (i2c_imx->hwdata->i2sr_clr_opcode & I2SR_IAL);
> >  			imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2SR);
> >  			return -EAGAIN;
> ...

> This looks strange. First the flag is cleared and then it is (in some
> cases) set again.
i.MX controllers require writing a 0 to clear these bits. Vybrid controllers
need writing a 1 for the same.

> If I2SR_IIF is set in temp you ack this irq without handling it. (Which
> might happen if atomic is set and irqs are off?!)
This patch is only about using the correct processor specific value for 
acknowledging an IRQ... But I think that returning EAGAIN (which aborts the
transfer) should be handling enough. At the next transfer, the controller will
be set back to master mode.

> I see this idiom is used in a few more places in the driver already, I
> didn't check but these might have the same problem maybe?

Best regards
Christian