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

[Dmitry Torokhov <dmitry.torokhov@gmail.com>]

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)?

Thanks.

-- 
Dmitry