[3.16.y-ckt stable] Patch "iio: mxs-lradc: make ADC reads not disable touchscreen interrupts" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    iio: mxs-lradc: make ADC reads not disable touchscreen interrupts

to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.16.y-queue

This patch is scheduled to be released in version 3.16.7-ckt9.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

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>From 6a820979b500ff5fb94c3f719bc168b30d9525f6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Kristina=20Mart=C5=A1enko?= <kristina.martsenko at gmail.com>
Date: Sun, 25 Jan 2015 18:28:20 +0200
Subject: iio: mxs-lradc: make ADC reads not disable touchscreen interrupts
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

commit 86bf7f3ef7e961e91e16dceb31ae0f583483b204 upstream.

Reading a channel through sysfs, or starting a buffered capture, will
currently turn off the touchscreen. This is because the read_raw() and
buffer preenable()/postdisable() callbacks disable interrupts for all
LRADC channels, including those the touchscreen uses.

So make the callbacks only disable interrupts for the channels they use.
This means channel 0 for read_raw() and channels 0-5 for the buffer (if
the touchscreen is enabled). Since the touchscreen uses different
channels (6 and 7), it no longer gets turned off.

Note that only i.MX28 is affected by this issue, i.MX23 should be fine.

Signed-off-by: Kristina Martšenko <kristina.martsenko at gmail.com>
Reviewed-by: Marek Vasut <marex at denx.de>
Signed-off-by: Jonathan Cameron <jic23 at kernel.org>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/staging/iio/adc/mxs-lradc.c | 20 +++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)

diff --git a/drivers/staging/iio/adc/mxs-lradc.c b/drivers/staging/iio/adc/mxs-lradc.c
index 0704291ec1e9..74c4a2d057af 100644
--- a/drivers/staging/iio/adc/mxs-lradc.c
+++ b/drivers/staging/iio/adc/mxs-lradc.c
@@ -220,6 +220,9 @@ struct mxs_lradc {
 	 */
 #define TOUCHSCREEN_VCHANNEL1		7
 #define TOUCHSCREEN_VCHANNEL2		6
+#define BUFFER_VCHANS_LIMITED		0x3f
+#define BUFFER_VCHANS_ALL		0xff
+	u8			buffer_vchans;

 	/*
 	 * Furthermore, certain LRADC channels are shared between touchscreen
@@ -824,7 +827,7 @@ static int mxs_lradc_read_single(struct iio_dev *iio_dev, int chan, int *val)
 	 * used if doing raw sampling.
 	 */
 	if (lradc->soc == IMX28_LRADC)
-		mxs_lradc_reg_clear(lradc, LRADC_CTRL1_MX28_LRADC_IRQ_EN_MASK,
+		mxs_lradc_reg_clear(lradc, LRADC_CTRL1_LRADC_IRQ_EN(0),
 			LRADC_CTRL1);
 	mxs_lradc_reg_clear(lradc, 0xff, LRADC_CTRL0);

@@ -1271,8 +1274,9 @@ static int mxs_lradc_buffer_preenable(struct iio_dev *iio)
 	}

 	if (lradc->soc == IMX28_LRADC)
-		mxs_lradc_reg_clear(lradc, LRADC_CTRL1_MX28_LRADC_IRQ_EN_MASK,
-							LRADC_CTRL1);
+		mxs_lradc_reg_clear(lradc,
+			lradc->buffer_vchans << LRADC_CTRL1_LRADC_IRQ_EN_OFFSET,
+			LRADC_CTRL1);
 	mxs_lradc_reg_clear(lradc, 0xff, LRADC_CTRL0);

 	for_each_set_bit(chan, iio->active_scan_mask, LRADC_MAX_TOTAL_CHANS) {
@@ -1308,8 +1312,9 @@ static int mxs_lradc_buffer_postdisable(struct iio_dev *iio)

 	mxs_lradc_reg_clear(lradc, 0xff, LRADC_CTRL0);
 	if (lradc->soc == IMX28_LRADC)
-		mxs_lradc_reg_clear(lradc, LRADC_CTRL1_MX28_LRADC_IRQ_EN_MASK,
-					LRADC_CTRL1);
+		mxs_lradc_reg_clear(lradc,
+			lradc->buffer_vchans << LRADC_CTRL1_LRADC_IRQ_EN_OFFSET,
+			LRADC_CTRL1);

 	kfree(lradc->buffer);
 	mutex_unlock(&lradc->lock);
@@ -1546,6 +1551,11 @@ static int mxs_lradc_probe(struct platform_device *pdev)

 	touch_ret = mxs_lradc_probe_touchscreen(lradc, node);

+	if (touch_ret == 0)
+		lradc->buffer_vchans = BUFFER_VCHANS_LIMITED;
+	else
+		lradc->buffer_vchans = BUFFER_VCHANS_ALL;
+
 	/* Grab all IRQ sources */
 	for (i = 0; i < of_cfg->irq_count; i++) {
 		lradc->irq[i] = platform_get_irq(pdev, i);