linux-kernel - RE: [PATCH v1] Input: elants_i2c: Add Elan touchscreen support

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Date:	Thu, 20 Nov 2014 20:25:15 +0800
From:	ELAN 劉嘉駿 <scott.liu@....com.tw>
To:	"'Oliver Neukum'" <oneukum@...e.de>,
	"'Dmitry Torokhov'" <dmitry.torokhov@...il.com>
Cc:	<linux-kernel@...r.kernel.org>, <linux-input@...r.kernel.org>,
	"'Vincent Wang'" <vincent.wang@....com.tw>,
	"'Jeff Chuang'" <jeff.chuang@....com.tw>,
	"'Benson Leung'" <bleung@...omium.org>,
	"'Benjamin Tissoires'" <benjamin.tissoires@...il.com>,
	"'Henrik Rydberg'" <rydberg@...omail.se>,
	"'David Herrmann'" <dh.herrmann@...il.com>
Subject: RE: [PATCH v1] Input: elants_i2c: Add Elan touchscreen support


Hi Oliver:

-----Original Message-----
From: Oliver Neukum [mailto:oneukum@...e.de] 
Sent: Thursday, November 20, 2014 6:32 PM
To: Dmitry Torokhov
Cc: scott; linux-kernel@...r.kernel.org; linux-input@...r.kernel.org; Vincent Wang; Jeff Chuang; Benson Leung; Benjamin Tissoires; Henrik Rydberg; David Herrmann
Subject: Re: [PATCH v1] Input: elants_i2c: Add Elan touchscreen support



> +static int elants_i2c_sw_reset(struct i2c_client *client) {
> +       const u8 soft_rst_cmd[] = { 0x77, 0x77, 0x77, 0x77 };
> +       int error;
> +
> +       error = elants_i2c_send(client, soft_rst_cmd,
> +                               sizeof(soft_rst_cmd));
> +       if (error) {
> +               dev_err(&client->dev, "software reset failed: %d\n",
> error);
> +               return error;
> +       }
> +
> +       /*
> +        * We should wait at least 10 msec (but no more than 40)
> before
> +        * sending fastboot or IAP command to the device.
> +        */
> +       msleep(30);

If timing is critical in both ways, you should take our guarantee if sufficient sleep. I suggest you sleep 11msecs.

Sorry, this is our firmware tricky but it should be sleep longer than 30ms. Actually 70ms.
(Dmitry, I need to modify this delay time to 70ms. Sorry for the changed over and over again; 
	because we consider big sensor solution which need to use more ICs and need more longer delay)

thanks,
Scott

> +static int elants_i2c_initialize(struct elants_data *ts) {
> +       struct i2c_client *client = ts->client;
> +       int error, retry_cnt;
> +       const u8 hello_packet[] = { 0x55, 0x55, 0x55, 0x55 };
> +       const u8 recov_packet[] = { 0x55, 0x55, 0x80, 0x80 };
> +       u8 buf[HEADER_SIZE];
> +

Strictly speaking you should disable preemption here.


> +       for (retry_cnt = 0; retry_cnt < MAX_RETRIES; retry_cnt++) {
> +               error = elants_i2c_sw_reset(client);
> +               if (error) {
> +                       /* Continue initializing if it's the last try
> */
> +                       if (retry_cnt < MAX_RETRIES - 1)
> +                               continue;
> +               }

	Regards
		Oliver

--
Oliver Neukum <oneukum@...e.de>


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