On Sun, Mar 22, 2020 at 03:30:04PM +0100, Wolfram Sang wrote: > > > + /* FIXME: only single write request supported to 7-bit addr */ > > Hmm, this is quite limited. Would it be very hard to support multiple > messages? Or reads? 10 bits don't matter. I don't expect this to be used for much more than a simple write to PMIC to kill the power. So this patch is tailor made for exactly this purpose. Though, if you would go for full support of atomic transfers, then I would suggest to hack the non-atomic path to be usable in atomic mode instead (some I2C drivers do just that, eg. i2c-tegra). BTW, I found this comment in i2c-core.h: * We only allow atomic transfers for very late communication, e.g. to send * the powerdown command to a PMIC. Atomic transfers are a corner case and not * for generic use! I think this covers the idea. > > + if (!dev->pdata->has_alt_cmd) > > + return -EOPNOTSUPP; > > We should handle this in probe(), I think: > > if (dev->pdata->has_alt_cmd) > at91_twi_algorithm.master_xfer_atomic = at91_twi_xfer_atomic; This would mean writable ops structure - something I try hard to avoid. We can use another copy of i2c_algorithm structure if needed, though. Best Regards Michał Mirosław
