Patch "iio: adc: ti_am335x_adc: Increase timeout value waiting for ADC sample" has been added to the 4.7-stable tree

Patch "iio: adc: ti_am335x_adc: Increase timeout value waiting for ADC sample" has been added to the 4.7-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    iio: adc: ti_am335x_adc: Increase timeout value waiting for ADC sample

to the 4.7-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-adc-ti_am335x_adc-increase-timeout-value-waiting-for-adc-sample.patch
and it can be found in the queue-4.7 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 7175cce1c3f1d8c8840d2004f78f96a3904249b5 Mon Sep 17 00:00:00 2001
From: Vignesh R <vigneshr@ti.com>
Date: Wed, 17 Aug 2016 17:43:01 +0530
Subject: iio: adc: ti_am335x_adc: Increase timeout value waiting for ADC sample

From: Vignesh R <vigneshr@ti.com>

commit 7175cce1c3f1d8c8840d2004f78f96a3904249b5 upstream.

Now that open delay and sample delay for each channel is configurable
via DT, the default IDLE_TIMEOUT value is not enough as this is
calculated based on hardcoded macros. This results in driver returning
EBUSY sometimes. Fix this by increasing the timeout
value based on maximum value possible to open delay and sample delays
for each channel.

Fixes: 5dc11e810676e ("iio: adc: ti_am335x_adc: make sample delay, open delay, averaging DT parameters")
Signed-off-by: Vignesh R <vigneshr@ti.com>
Acked-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/iio/adc/ti_am335x_adc.c      |    2 +-
 include/linux/mfd/ti_am335x_tscadc.h |    8 ++++----
 2 files changed, 5 insertions(+), 5 deletions(-)

--- a/drivers/iio/adc/ti_am335x_adc.c
+++ b/drivers/iio/adc/ti_am335x_adc.c
@@ -382,7 +382,7 @@ static int tiadc_read_raw(struct iio_dev
 
 	am335x_tsc_se_set_once(adc_dev->mfd_tscadc, step_en);
 
-	timeout = jiffies + usecs_to_jiffies
+	timeout = jiffies + msecs_to_jiffies
 				(IDLE_TIMEOUT * adc_dev->channels);
 	/* Wait for Fifo threshold interrupt */
 	while (1) {
--- a/include/linux/mfd/ti_am335x_tscadc.h
+++ b/include/linux/mfd/ti_am335x_tscadc.h
@@ -138,16 +138,16 @@
 /*
  * time in us for processing a single channel, calculated as follows:
  *
- * num cycles = open delay + (sample delay + conv time) * averaging
+ * max num cycles = open delay + (sample delay + conv time) * averaging
  *
- * num cycles: 152 + (1 + 13) * 16 = 376
+ * max num cycles: 262143 + (255 + 13) * 16 = 266431
  *
  * clock frequency: 26MHz / 8 = 3.25MHz
  * clock period: 1 / 3.25MHz = 308ns
  *
- * processing time: 376 * 308ns = 116us
+ * max processing time: 266431 * 308ns = 83ms(approx)
  */
-#define IDLE_TIMEOUT 116 /* microsec */
+#define IDLE_TIMEOUT 83 /* milliseconds */
 
 #define TSCADC_CELLS		2
 


Patches currently in stable-queue which might be from vigneshr@ti.com are

queue-4.7/iio-adc-ti_am335x_adc-protect-fifo1-from-concurrent-access.patch
queue-4.7/iio-adc-ti_am335x_adc-increase-timeout-value-waiting-for-adc-sample.patch