Re: [PATCH] Input: goodix: Add support for capacitive home button found on some x86 tablets

["Sergei A. Trusov" <sergei.a.trusov@ya.ru>]

On Tuesday, 20 June 2017 19:29:01 +10 Bastien Nocera wrote:
> On Tue, 2017-06-20 at 19:26 +1000, Sergei A. Trusov wrote:
> > 
> <snip>
> > Thank you for this point. Now I see all the changes above are
> > redundant:
> > we can use a value returned in the *data buffer. It is enough to add 
> > only two lines of code to achieve the behaviour of this entire patch.
> 
> A bit more with a comment explaining the reason behind those 2 lines,
> but shorter patches get my vote ;)

Current goodix_ts_read_input_report() function puts data from hardware
into point_data buffer. Then in masks high niblle of the first byte and 
returns it as touch_num. We need this masked nibble to check, so I was 
trying to remove mask operation. After your comment I just realized that
proposed patch should be much shorter. I have included more context lines
to make cleaner my attempts to explain (as I am affraid my English is not
so good):

---
diff --git a/drivers/input/touchscreen/goodix.c b/drivers/input/touchscreen/goodix.c
index 240b16f3ee97..0c3825c39288 100644
--- a/drivers/input/touchscreen/goodix.c
+++ b/drivers/input/touchscreen/goodix.c
@@ -262,16 +262,18 @@ static void goodix_process_events(struct goodix_ts_data *ts)
 	u8  point_data[1 + GOODIX_CONTACT_SIZE * GOODIX_MAX_CONTACTS];
 	int touch_num;
 	int i;
 
 	touch_num = goodix_ts_read_input_report(ts, point_data);
 	if (touch_num < 0)
 		return;
 
+	input_report_key(ts->input_dev, KEY_LEFTMETA, !!(point_data[0] & 0x10));
+
 	for (i = 0; i < touch_num; i++)
 		goodix_ts_report_touch(ts,
 				&point_data[1 + GOODIX_CONTACT_SIZE * i]);
 
 	input_mt_sync_frame(ts->input_dev);
 	input_sync(ts->input_dev);
 }
 
@@ -607,16 +609,18 @@ static int goodix_request_input_dev(struct goodix_ts_data *ts)
 
 	ts->input_dev->name = "Goodix Capacitive TouchScreen";
 	ts->input_dev->phys = "input/ts";
 	ts->input_dev->id.bustype = BUS_I2C;
 	ts->input_dev->id.vendor = 0x0416;
 	ts->input_dev->id.product = ts->id;
 	ts->input_dev->id.version = ts->version;
 
+	input_set_capability(ts->input_dev, EV_KEY, KEY_LEFTMETA);
+
 	error = input_register_device(ts->input_dev);
 	if (error) {
 		dev_err(&ts->client->dev,
 			"Failed to register input device: %d", error);
 		return error;
 	}
 
 	return 0;