Patch "iio: adc: xilinx-xadc: Don't clobber preset voltage/temperature thresholds" has been added to the 5.10-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

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

    iio: adc: xilinx-xadc: Don't clobber preset voltage/temperature thresholds

to the 5.10-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-xilinx-xadc-don-t-clobber-preset-voltage-tem.patch
and it can be found in the queue-5.10 subdirectory.

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



commit 9c2528f8b330dda82ad8f1d021edc591e6fa95c3
Author: Robert Hancock <robert.hancock@xxxxxxxxxx>
Date:   Thu Sep 14 18:10:18 2023 -0600

    iio: adc: xilinx-xadc: Don't clobber preset voltage/temperature thresholds
    
    [ Upstream commit 8d6b3ea4d9eaca80982442b68a292ce50ce0a135 ]
    
    In the probe function, the driver was reading out the thresholds already
    set in the core, which can be configured by the user in the Vivado tools
    when the FPGA image is built. However, it later clobbered those values
    with zero or maximum values. In particular, the overtemperature shutdown
    threshold register was overwritten with the max value, which effectively
    prevents the FPGA from shutting down when the desired threshold was
    eached, potentially risking hardware damage in that case.
    
    Remove this code to leave the preconfigured default threshold values
    intact.
    
    The code was also disabling all alarms regardless of what enable state
    they were left in by the FPGA image, including the overtemperature
    shutdown feature. Leave these bits in their original state so they are
    not unconditionally disabled.
    
    Fixes: bdc8cda1d010 ("iio:adc: Add Xilinx XADC driver")
    Signed-off-by: Robert Hancock <robert.hancock@xxxxxxxxxx>
    Acked-by: O'Griofa, Conall <conall.ogriofa@xxxxxxx>
    Tested-by: O'Griofa, Conall <conall.ogriofa@xxxxxxx>
    Link: https://lore.kernel.org/r/20230915001019.2862964-2-robert.hancock@xxxxxxxxxx
    Cc: <Stable@xxxxxxxxxxxxxxx>
    Signed-off-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/iio/adc/xilinx-xadc-core.c b/drivers/iio/adc/xilinx-xadc-core.c
index fec266682e91d..30b5a17ce41a7 100644
--- a/drivers/iio/adc/xilinx-xadc-core.c
+++ b/drivers/iio/adc/xilinx-xadc-core.c
@@ -1334,28 +1334,6 @@ static int xadc_probe(struct platform_device *pdev)
 	if (ret)
 		return ret;
 
-	/* Disable all alarms */
-	ret = xadc_update_adc_reg(xadc, XADC_REG_CONF1, XADC_CONF1_ALARM_MASK,
-				  XADC_CONF1_ALARM_MASK);
-	if (ret)
-		return ret;
-
-	/* Set thresholds to min/max */
-	for (i = 0; i < 16; i++) {
-		/*
-		 * Set max voltage threshold and both temperature thresholds to
-		 * 0xffff, min voltage threshold to 0.
-		 */
-		if (i % 8 < 4 || i == 7)
-			xadc->threshold[i] = 0xffff;
-		else
-			xadc->threshold[i] = 0;
-		ret = xadc_write_adc_reg(xadc, XADC_REG_THRESHOLD(i),
-			xadc->threshold[i]);
-		if (ret)
-			return ret;
-	}
-
 	/* Go to non-buffered mode */
 	xadc_postdisable(indio_dev);