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
>
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