linux-kernel - [PATCH] iio: adc: rockchip_saradc: Explicitly disable ADC on probe

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Message-Id: <1469475540-26855-1-git-send-email-linux@roeck-us.net>
Date:	Mon, 25 Jul 2016 12:39:00 -0700
From:	Guenter Roeck <linux@...ck-us.net>
To:	Jonathan Cameron <jic23@...nel.org>
Cc:	Heiko Stuebner <heiko@...ech.de>, linux-iio@...r.kernel.org,
	linux-rockchip@...ts.infradead.org, linux-kernel@...r.kernel.org,
	Caesar Wang <wxt@...k-chips.com>, dianders@...omium.org,
	Guenter Roeck <linux@...ck-us.net>
Subject: [PATCH] iio: adc: rockchip_saradc: Explicitly disable ADC on probe

If the ADC is read for the first time, the caller gets a timeout error,
and the kernel log shows

read channel() error: -110

The ADC may be enabled on boot, and needs to be explicitly disabled
for a read sequence to work (otherwise there is no completion interrupt).
Disaple it explicitly in the probe function.

Fixes: 44d6f2ef94f9 ("iio: adc: add driver for Rockchip saradc")
Signed-off-by: Guenter Roeck <linux@...ck-us.net>
---
 drivers/iio/adc/rockchip_saradc.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/iio/adc/rockchip_saradc.c b/drivers/iio/adc/rockchip_saradc.c
index f9ad6c2d6821..6aa3271d86b5 100644
--- a/drivers/iio/adc/rockchip_saradc.c
+++ b/drivers/iio/adc/rockchip_saradc.c
@@ -280,6 +280,9 @@ static int rockchip_saradc_probe(struct platform_device *pdev)
 		goto err_pclk;
 	}
 
+	/* Make sure ADC is disabled */
+	writel_relaxed(0, info->regs + SARADC_CTRL);
+
 	platform_set_drvdata(pdev, indio_dev);
 
 	indio_dev->name = dev_name(&pdev->dev);
-- 
2.5.0