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From: Robert Hancock <robert.hancock@calian.com>
To: Jonathan Cameron <jic23@kernel.org>
Cc: Lars-Peter Clausen <lars@metafoo.de>,
	Michal Simek <michal.simek@amd.com>,
	Anand Ashok Dumbre <anandash@xilinx.com>,
	linux-iio@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	Robert Hancock <robert.hancock@calian.com>
Subject: [PATCH 1/2] iio: adc: xilinx-xadc: Don't clobber preset voltage/temperature thresholds
Date: Thu, 14 Sep 2023 15:24:31 -0600	[thread overview]
Message-ID: <20230914212432.2842010-2-robert.hancock@calian.com> (raw)
In-Reply-To: <20230914212432.2842010-1-robert.hancock@calian.com>

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.

Fixes: bdc8cda1d010 ("iio:adc: Add Xilinx XADC driver")
Signed-off-by: Robert Hancock <robert.hancock@calian.com>
---
 drivers/iio/adc/xilinx-xadc-core.c | 16 ----------------
 1 file changed, 16 deletions(-)

diff --git a/drivers/iio/adc/xilinx-xadc-core.c b/drivers/iio/adc/xilinx-xadc-core.c
index dba73300f894..88d523ac7881 100644
--- a/drivers/iio/adc/xilinx-xadc-core.c
+++ b/drivers/iio/adc/xilinx-xadc-core.c
@@ -1429,22 +1429,6 @@ static int xadc_probe(struct platform_device *pdev)
 	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);
 
-- 
2.41.0


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WARNING: multiple messages have this Message-ID (diff)
From: Robert Hancock <robert.hancock@calian.com>
To: Jonathan Cameron <jic23@kernel.org>
Cc: Lars-Peter Clausen <lars@metafoo.de>,
	Michal Simek <michal.simek@amd.com>,
	Anand Ashok Dumbre <anandash@xilinx.com>,
	linux-iio@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	Robert Hancock <robert.hancock@calian.com>
Subject: [PATCH 1/2] iio: adc: xilinx-xadc: Don't clobber preset voltage/temperature thresholds
Date: Thu, 14 Sep 2023 15:24:31 -0600	[thread overview]
Message-ID: <20230914212432.2842010-2-robert.hancock@calian.com> (raw)
In-Reply-To: <20230914212432.2842010-1-robert.hancock@calian.com>

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.

Fixes: bdc8cda1d010 ("iio:adc: Add Xilinx XADC driver")
Signed-off-by: Robert Hancock <robert.hancock@calian.com>
---
 drivers/iio/adc/xilinx-xadc-core.c | 16 ----------------
 1 file changed, 16 deletions(-)

diff --git a/drivers/iio/adc/xilinx-xadc-core.c b/drivers/iio/adc/xilinx-xadc-core.c
index dba73300f894..88d523ac7881 100644
--- a/drivers/iio/adc/xilinx-xadc-core.c
+++ b/drivers/iio/adc/xilinx-xadc-core.c
@@ -1429,22 +1429,6 @@ static int xadc_probe(struct platform_device *pdev)
 	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);
 
-- 
2.41.0


  reply	other threads:[~2023-09-14 21:25 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-09-14 21:24 [PATCH 0/2] Xilinx XADC fixes Robert Hancock
2023-09-14 21:24 ` Robert Hancock
2023-09-14 21:24 ` Robert Hancock [this message]
2023-09-14 21:24   ` [PATCH 1/2] iio: adc: xilinx-xadc: Don't clobber preset voltage/temperature thresholds Robert Hancock
2023-09-14 23:45   ` Robert Hancock
2023-09-14 23:45     ` Robert Hancock
2023-09-14 21:24 ` [PATCH 2/2] iio: adc: xilinx-xadc: Correct temperature offset/scale for UltraScale Robert Hancock
2023-09-14 21:24   ` Robert Hancock

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