This is a note to let you know that I've just added the patch titled
iio: mxs-lradc: make ADC reads not unschedule touchscreen conversions
to the 3.19-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
iio-mxs-lradc-make-adc-reads-not-unschedule-touchscreen-conversions.patch
and it can be found in the queue-3.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 6abe0300a1d5242f4ff89257197f284679af1a06 Mon Sep 17 00:00:00 2001
From: Kristina Martšenko <kristina.martsenko@xxxxxxxxx>
Date: Sun, 25 Jan 2015 18:28:21 +0200
Subject: iio: mxs-lradc: make ADC reads not unschedule touchscreen conversions
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From: Kristina Martšenko <kristina.martsenko@xxxxxxxxx>
commit 6abe0300a1d5242f4ff89257197f284679af1a06 upstream.
Reading a channel through sysfs, or starting a buffered capture, can
occasionally turn off the touchscreen.
This is because the read_raw() and buffer preenable()/postdisable()
callbacks unschedule current conversions on all channels. If a delay
channel happens to schedule a touchscreen conversion at the same time,
the conversion gets cancelled and the touchscreen sequence stops.
This is probably related to this note from the reference manual:
"If a delay group schedules channels to be sampled and a manual
write to the schedule field in CTRL0 occurs while the block is
discarding samples, the LRADC will switch to the new schedule
and will not sample the channels that were previously scheduled.
The time window for this to happen is very small and lasts only
while the LRADC is discarding samples."
So make the callbacks only unschedule conversions 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.
This is tested and fixes the issue on i.MX28, but hasn't been tested on
i.MX23.
Signed-off-by: Kristina Martšenko <kristina.martsenko@xxxxxxxxx>
Reviewed-by: Marek Vasut <marex@xxxxxxx>
Signed-off-by: Jonathan Cameron <jic23@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/staging/iio/adc/mxs-lradc.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
--- a/drivers/staging/iio/adc/mxs-lradc.c
+++ b/drivers/staging/iio/adc/mxs-lradc.c
@@ -824,7 +824,7 @@ static int mxs_lradc_read_single(struct
if (lradc->soc == IMX28_LRADC)
mxs_lradc_reg_clear(lradc, LRADC_CTRL1_LRADC_IRQ_EN(0),
LRADC_CTRL1);
- mxs_lradc_reg_clear(lradc, 0xff, LRADC_CTRL0);
+ mxs_lradc_reg_clear(lradc, 0x1, LRADC_CTRL0);
/* Enable / disable the divider per requirement */
if (test_bit(chan, &lradc->is_divided))
@@ -1272,7 +1272,7 @@ static int mxs_lradc_buffer_preenable(st
mxs_lradc_reg_clear(lradc,
lradc->buffer_vchans << LRADC_CTRL1_LRADC_IRQ_EN_OFFSET,
LRADC_CTRL1);
- mxs_lradc_reg_clear(lradc, 0xff, LRADC_CTRL0);
+ mxs_lradc_reg_clear(lradc, lradc->buffer_vchans, LRADC_CTRL0);
for_each_set_bit(chan, iio->active_scan_mask, LRADC_MAX_TOTAL_CHANS) {
ctrl4_set |= chan << LRADC_CTRL4_LRADCSELECT_OFFSET(ofs);
@@ -1305,7 +1305,7 @@ static int mxs_lradc_buffer_postdisable(
mxs_lradc_reg_clear(lradc, LRADC_DELAY_TRIGGER_LRADCS_MASK |
LRADC_DELAY_KICK, LRADC_DELAY(0));
- mxs_lradc_reg_clear(lradc, 0xff, LRADC_CTRL0);
+ mxs_lradc_reg_clear(lradc, lradc->buffer_vchans, LRADC_CTRL0);
if (lradc->soc == IMX28_LRADC)
mxs_lradc_reg_clear(lradc,
lradc->buffer_vchans << LRADC_CTRL1_LRADC_IRQ_EN_OFFSET,
Patches currently in stable-queue which might be from kristina.martsenko@xxxxxxxxx are
queue-3.19/iio-mxs-lradc-separate-touchscreen-and-buffer-virtual-channels.patch
queue-3.19/iio-mxs-lradc-make-adc-reads-not-disable-touchscreen-interrupts.patch
queue-3.19/iio-mxs-lradc-make-adc-reads-not-unschedule-touchscreen-conversions.patch
queue-3.19/iio-mxs-lradc-only-update-the-buffer-when-its-conversions-have-finished.patch
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