linux-kernel - Re: [PATCH 2/2] iio: exynos-adc: add experimental touchscreen support

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Date:	Mon, 21 Jul 2014 07:44:42 -0700
From:	Dmitry Torokhov <dmitry.torokhov@...il.com>
To:	Arnd Bergmann <arnd@...db.de>
Cc:	Jonathan Cameron <jic23@...nel.org>,
	linux-arm-kernel@...ts.infradead.org,
	Chanwoo Choi <cw00.choi@...sung.com>, ch.naveen@...sung.com,
	mark.rutland@....com, devicetree@...r.kernel.org,
	kgene.kim@...sung.com, pawel.moll@....com,
	ijc+devicetree@...lion.org.uk, linux-iio@...r.kernel.org,
	t.figa@...sung.com, rdunlap@...radead.org,
	linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-samsung-soc@...r.kernel.org, kyungmin.park@...sung.com,
	robh+dt@...nel.org, galak@...eaurora.org, heiko.stuebner@...com,
	Ben Dooks <ben-linux@...ff.org>,
	linux-input <linux-input@...r.kernel.org>
Subject: Re: [PATCH 2/2] iio: exynos-adc: add experimental touchscreen support

On Mon, Jul 21, 2014 at 12:23:58PM +0200, Arnd Bergmann wrote:
> On Sunday 20 July 2014 13:28:42 Dmitry Torokhov wrote:
> > On Sun, Jul 20, 2014 at 02:51:37PM +0100, Jonathan Cameron wrote:
> > > >>+
> > > >>+    do {
> > > >>+        ret =exynos_read_s3c64xx_ts(dev, NULL, &x, &y, IIO_CHAN_INFO_RAW);
> > > >= exynos
> > > >>+        if (ret == -ETIMEDOUT)
> > > >>+            break;
> > > >>+
> > > >>+        pressed = x & y & ADC_DATX_PRESSED;
> > > >>+        if (!pressed)
> > > >>+            break;
> > > >>+
> > > >>+        input_report_abs(info->input, ABS_X, x & ADC_DATX_MASK);
> > > >>+        input_report_abs(info->input, ABS_Y, y & ADC_DATX_MASK);
> > > >>+        input_report_key(info->input, BTN_TOUCH, 1);
> > > >>+        input_sync(info->input);
> > > >>+
> > > >>+        msleep(1);
> > > >>+    } while (1);
> > 
> > It would be nice to actually close the device even if someone is
> > touching screen. Please implement open/close methods and have them set a
> > flag that you would check here.
> 
> Ok. I think it's even better to move the request_irq() into the open function,
> which will avoid the flag and defer the error handling into the actual opening,
> as well as syncing the running irq with the close function.

I do not quite like acquiring resources needed in open. I think drivers should
do all resource acquisition in probe() and leave open()/close() to
activate/quiesce devices.

> 
> > > >>+    /* data from s3c2410_ts driver */
> > > >>+    info->input->name = "S3C24xx TouchScreen";
> > > >>+    info->input->id.bustype = BUS_HOST;
> > > >>+    info->input->id.vendor = 0xDEAD;
> > > >>+    info->input->id.product = 0xBEEF;
> > 
> > You do not need to fill these entries with fake data.
> 
> Ok, I wondered about this, but didn't want to change too much from
> the old driver (I changed the version number).
> 
> > > >>+    info->input->id.version = 0x0200;
> 
> Do I need this?

Not really.

Thanks.

-- 
Dmitry
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