Hi, I add Cyrille for FIFO part. On Mon, Jan 30, 2017 at 06:25:33PM +0100, Alexandre Belloni wrote: > When going to suspend, the I2C registers may be lost because the power to > VDDcore is cut. Save them and restore them when resuming. > > Signed-off-by: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxxxxxxxxx> > --- > drivers/i2c/busses/i2c-at91.c | 24 ++++++++++++++++++++++++ > 1 file changed, 24 insertions(+) > > diff --git a/drivers/i2c/busses/i2c-at91.c b/drivers/i2c/busses/i2c-at91.c > index 0b86c6173e07..633bdd899952 100644 > --- a/drivers/i2c/busses/i2c-at91.c > +++ b/drivers/i2c/busses/i2c-at91.c > @@ -140,6 +140,12 @@ struct at91_twi_dev { > unsigned transfer_status; > struct i2c_adapter adapter; > unsigned twi_cwgr_reg; > + struct { > + u32 mmr; > + u32 imr; > + u32 fmr; > + u32 fimr; > + } cache; Do we really need it? For instance MMR is only written in at91_twi_xfer(). I am not sure we can continue the transfer when resuming. I assume we will need to perform a new transfer from a proper state. Moreover at91_init_twi_bus() is called on resume, it will perform a reset and it seems it can lead to strange behaviors: "Note that issuing a software while transmitting might leave a slave in an unknown state holding the TWD line. In such case, a Bus Clear Command will allow to make the slave release the TWD line (the first frame sent afterwards might not be received properly by the slave)." I think fimr is useless, AT91_TWI_FIER and AT91_TWI_FIDR are not used in the current code. Regards Ludovic > struct at91_twi_pdata *pdata; > bool use_dma; > bool use_alt_cmd; > @@ -1172,6 +1178,15 @@ static int at91_twi_runtime_resume(struct device *dev) > > static int at91_twi_suspend_noirq(struct device *dev) > { > + struct at91_twi_dev *twi_dev = dev_get_drvdata(dev); > + > + twi_dev->cache.mmr = at91_twi_read(twi_dev, AT91_TWI_MMR); > + twi_dev->cache.imr = at91_twi_read(twi_dev, AT91_TWI_IMR); > + if (twi_dev->fifo_size) { > + twi_dev->cache.fmr = at91_twi_read(twi_dev, AT91_TWI_FMR); > + twi_dev->cache.fimr = at91_twi_read(twi_dev, AT91_TWI_FIMR); > + } > + > if (!pm_runtime_status_suspended(dev)) > at91_twi_runtime_suspend(dev); > > @@ -1180,6 +1195,7 @@ static int at91_twi_suspend_noirq(struct device *dev) > > static int at91_twi_resume_noirq(struct device *dev) > { > + struct at91_twi_dev *twi_dev = dev_get_drvdata(dev); > int ret; > > if (!pm_runtime_status_suspended(dev)) { > @@ -1191,6 +1207,14 @@ static int at91_twi_resume_noirq(struct device *dev) > pm_runtime_mark_last_busy(dev); > pm_request_autosuspend(dev); > > + at91_init_twi_bus(twi_dev); > + at91_twi_write(twi_dev, AT91_TWI_MMR, twi_dev->cache.mmr); > + at91_twi_write(twi_dev, AT91_TWI_IER, twi_dev->cache.imr); > + if (twi_dev->fifo_size) { > + at91_twi_write(twi_dev, AT91_TWI_FMR, twi_dev->cache.fmr); > + at91_twi_write(twi_dev, AT91_TWI_FIER, twi_dev->cache.fimr); > + } > + > return 0; > } > > -- > 2.11.0 > -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html