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

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Message-ID: <5158672.dMAnnUQc7Z@wuerfel>
Date:	Mon, 21 Jul 2014 12:23:58 +0200
From:	Arnd Bergmann <arnd@...db.de>
To:	Dmitry Torokhov <dmitry.torokhov@...il.com>
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 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.

> > >>+    /* 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?

> > >>@@ -576,6 +728,11 @@ static int exynos_adc_probe(struct platform_device *pdev)
> > >>  err_of_populate:
> > >>      device_for_each_child(&indio_dev->dev, NULL,
> > >>                  exynos_adc_remove_devices);
> > >>+    if (has_ts) {
> > >>+        input_unregister_device(info->input);
> > >>+        free_irq(info->tsirq, info);
> 
> Are we sure that device is quiesced here and interrupt won't arrive
> between input_unregister_device() and free_irq()? I guess if you
> properly implement open/close it won't matter.
 
Should be fixed now.

> > >>+err_iio:
> > >>      iio_device_unregister(indio_dev);
> > >>  err_irq:
> > >>      free_irq(info->irq, info);
> > >>@@ -595,9 +752,12 @@ static int exynos_adc_remove(struct platform_device *pdev)
> > >>      struct iio_dev *indio_dev = platform_get_drvdata(pdev);
> > >>      struct exynos_adc *info = iio_priv(indio_dev);
> > >>
> > >>+    input_free_device(info->input);
> 
> Should be unregister, not free.

Ok.

Thanks a lot for the review! I'll send out the new version after some build testing.

	Arnd
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