Re: [PATCH] i2c: spacemit: fix detect issue

Aurelien Jarno
2025-11-06T18:17:16Z

Hi,

On 2025-11-06 13:38, Troy Mitchell wrote:
> On Thu, Nov 06, 2025 at 06:34:26AM +0100, Aurelien Jarno wrote:
> > Hi,
> >
> > On 2025-11-06 09:05, Troy Mitchell wrote:
> > > On Wed, Nov 05, 2025 at 11:44:00PM +0100, Aurelien Jarno wrote:
> > > > Hi,
> > > >
> > > > On 2025-11-03 15:06, Troy Mitchell wrote:
> > > [...]
> > > > > if (i2c->status & (SPACEMIT_SR_BED | SPACEMIT_SR_ALD)) {
> > > > > spacemit_i2c_reset(i2c);
> > > > > - return -EAGAIN;
> > > > > + if (i2c->status & SPACEMIT_SR_ALD)
> > > > > + return -EAGAIN;
> > > > > }
> > > >
> > > > This makes the resulting code, while correct, complex to understand as
> > > > it is now two really different errors, as you explained well in the
> > > > commit message.
> > > >
> > > > I therefore suggest to organize the code as:
> > > >
> > > > /* Arbitration Loss Detected */
> > > > if (i2c->status & SPACEMIT_SR_ALD) {
> > > > spacemit_i2c_reset(i2c);
> > > > return -EAGAIN;
> > > > }
> > > >
> > > > /* Bus Error No ACK/NAK */
> > > > if (i2c->status & SPACEMIT_SR_BED) {
> > > > spacemit_i2c_reset(i2c);
> > > > }
> > > Thanks. I'll fix it in the next version.
> > > >
> > > >
> > > > > return i2c->status & SPACEMIT_SR_ACKNAK ? -ENXIO : -EIO;
> > > > > @@ -491,6 +492,8 @@ static int spacemit_i2c_xfer(struct i2c_adapter *adapt, struct i2c_msg *msgs, in
> > > > >
> > > > > spacemit_i2c_init(i2c);
> > > > >
> > > > > + spacemit_i2c_clear_int_status(i2c, SPACEMIT_I2C_INT_STATUS_MASK);
> > > > > +
> > > >
> > > > This sounds good to start the transfer with a clean interrupt state. I
> > > > just wonder if it should be moved to spacemit_i2c_init(), ie where the
> > > > corresponding interrupts are enabled.
> > > Uh, We can move it actually. But is it essentail?
> >
> > For me ensuring that the interrupt status is in a clean state after
> > enabling the interrupt is part of the initialization.
> Yes, I agree that.
> > Furthermore if
> > spacemit_i2c_init() has to be called from another place, it's very
> > likely that it's also needed to get interrupt status in a clean state.
> Why we need to call init() in other place?
> Could you give me a cese?

Currently there is no need to do that. However if the driver is extended
(e.g. to add new features) and spacemit_i2c_init() needs to be called
from another place, it is likely that a reset of the interrupt status
should also be included. Therefore it's better to just include it
directly in spacemit_i2c_init().

Regards
Aurelien

--
Aurelien Jarno GPG: 4096R/1DDD8C9B
aurelien@aurel32.net http://aurel32.net