RE: [PATCH 1/2] input: egalax_ts: switch to i2c interface before wake up

[BOUGH CHEN <haibo.chen@nxp.com>]

> -----Original Message-----
> From: Dmitry Torokhov <dmitry.torokhov@gmail.com>
> Sent: 2020年3月10日 12:22
> To: BOUGH CHEN <haibo.chen@nxp.com>
> Cc: linux-input@vger.kernel.org; dl-linux-imx <linux-imx@nxp.com>
> Subject: Re: [PATCH 1/2] input: egalax_ts: switch to i2c interface before
> wake up
> 
> Hi Haibo,
> 
> On Tue, Feb 11, 2020 at 04:41:11PM +0800, haibo.chen@nxp.com wrote:
> > From: Haibo Chen <haibo.chen@nxp.com>
> >
> > For HannStar (HSD100PXN1 Rev: 1-A00C11 F/W:0634) LVDS touch screen,
> it
> > has a special request for the EETI touch controller. The host needs to
> > trigger I2C event to device FW at booting first, and then the FW can
> > switch to I2C interface. Otherwise, the FW can’t  work with I2C
> > interface, and can't generate any interrupt when touch the screen.
> >
> > This patch send an I2C command before the device wake up, make sure
> > the device switch to I2C interface first.
> >
> > Signed-off-by: Haibo Chen <haibo.chen@nxp.com>
> > ---
> >  drivers/input/touchscreen/egalax_ts.c | 14 ++++++++++++++
> >  1 file changed, 14 insertions(+)
> >
> > diff --git a/drivers/input/touchscreen/egalax_ts.c
> > b/drivers/input/touchscreen/egalax_ts.c
> > index 83ac8c128192..5e35ca5edc7b 100644
> > --- a/drivers/input/touchscreen/egalax_ts.c
> > +++ b/drivers/input/touchscreen/egalax_ts.c
> > @@ -183,6 +183,20 @@ static int egalax_ts_probe(struct i2c_client
> *client,
> >  	ts->client = client;
> >  	ts->input_dev = input_dev;
> >
> > +	/* HannStar (HSD100PXN1 Rev: 1-A00C11 F/W:0634) LVDS touch
> > +	 * screen needs to trigger I2C event to device FW at booting
> > +	 * first, and then the FW can switch to I2C interface.
> > +	 * Otherwise, the FW can’t  work with I2C interface. So here
> > +	 * just use the exist function egalax_firmware_version() to
> > +	 * send a I2C command to the device, make sure the device FW
> > +	 * switch to I2C interface.
> > +	 */
> > +	error = egalax_firmware_version(client);
> > +	if (error) {
> > +		dev_err(&client->dev, "Failed to switch to I2C interface\n");
> > +		return error;
> > +	}
> > +
> >  	/* controller may be in sleep, wake it up. */
> >  	error = egalax_wake_up_device(client);
> >  	if (error) {
> 
> I think this should be part of egalax_wake_up_device(), in case where we do
> not have dedicated reset gpio. Also, instead of abusing firmware read, would
> a dummy byte read be enough (i2c_probe_func_quick_read)?

That's reasonable, I will move the change to egalax_wake_up_device(). I will have a try whether a dummy byte read can work.
Really thanks for your suggestion!

Regards,
Haibo Chen
> Thanks.
> 
> --
> Dmitry