Re: [PATCH v2 2/2] Input: atmel_mxt_ts - wake mXT1386 from deep-sleep mode

[Wang, Jiada]

Hi Dmitry

On 2020/09/20 4:49, Dmitry Osipenko wrote:
> 18.09.2020 18:55, Wang, Jiada пишет:
> ...
> > > >    +static void mxt_wake(struct mxt_data *data)
> > > > +{
> > > > +    struct i2c_client *client = data->client;
> > > > +    struct device *dev = &data->client->dev;
> > > > +    struct device_node *np = dev->of_node;
> > > > +    union i2c_smbus_data dummy;
> > > > +
> > > > +    if (!of_device_is_compatible(np, "atmel,mXT1386"))
> > > > +        return;
> > > I'm not sure whether you misses the previous answers from Dmitry
> > > Torokhov and Rob Herring, but they suggested to add a new device-tree
> > > property which should specify the atmel,wakeup-method.
> > I think Rob Herring prefers for the compatible solution than property.
>
> Actually, seems you're right. But I'm not sure now whether he just made
> a typo, because it's actually a board-specific option.
Right, I think since it is a board specific issue,
so "property" is the preferred way,
if I understand you correctly,
compatible combine with property is what you are suggesting, right?

> It could be more preferred to skip the i2c_smbus_xfer() for the NONE
> variant, but it also should be harmless in practice. I guess we indeed
> could keep the current variant of yours patch and then add a clarifying
> comment to the commit message and to the code, telling that
> i2c_smbus_xfer() is harmless in a case of the hardwired WAKE-LINE.
I will skip dummy read for "NONE" variant.

> > > There are 3 possible variants:
> > >
> > >     - NONE
> > >     - GPIO
> > >     - I2C-SCL
> > >
> > > Hence we should bail out from mxt_wake() if method is set to NONE or
> > > GPIO.
> > for "GPIO", we still need 25 ms sleep. but rather than a dummy read,
> > WAKE line need to be asserted before sleep.
>
> Correct, I just meant to bail out because GPIO is currently unsupported.

OK

> ...
> > > >    static int mxt_initialize(struct mxt_data *data)
> > > >    {
> > > >        struct i2c_client *client = data->client;
> > > >        int recovery_attempts = 0;
> > > >        int error;
> > > >    +    mxt_wake(data);
> > > > +
> > > >        while (1) {
> > >
> > > I assume the mxt_wake() should be placed here, since there is a 3
> > > seconds timeout in the end of the while-loop, meaning that device may
> > > get back into deep-sleep on a retry.
> > Can you elaborate a little more why exit from bootload mode after sleep
> > for 3 second could enter deep-sleep mode.
>
> The loop attempts to exit from bootload mode and then I suppose
> mxt_read_info_block() may fail if I2C "accidentally" fails, hence the
> deep-sleep mode still will be enabled on a retry.
>
> The datasheet says that there are 2 seconds since the time of the last
> I2C access before TS is put back into auto-sleep if deep-sleep mode is
> enabled. The wait-loop has msleep(3000).

OK, thanks for the clarification

Thanks,
Jiada
>