linux-kernel - [PATCH 2/3] gnss: sirf: force hibernate mode on probe

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Message-Id: <20190122172255.17944-3-johan@kernel.org>
Date:   Tue, 22 Jan 2019 18:22:54 +0100
From:   Johan Hovold <johan@...nel.org>
To:     linux-kernel@...r.kernel.org
Cc:     Andreas Kemnade <andreas@...nade.info>,
        Johan Hovold <johan@...nel.org>
Subject: [PATCH 2/3] gnss: sirf: force hibernate mode on probe

Make sure to put the receiver in hibernate mode in case it is already
active during probe in order to avoid wasting power until first open or
suspend.

This can happen, for example, after a reset or non-clean shutdown, and
possibly also due to glitches during power-on.

Reported-by: Andreas Kemnade <andreas@...nade.info>
Signed-off-by: Johan Hovold <johan@...nel.org>
---
 drivers/gnss/sirf.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/drivers/gnss/sirf.c b/drivers/gnss/sirf.c
index 8e3f6a776e02..f9a9d00dec98 100644
--- a/drivers/gnss/sirf.c
+++ b/drivers/gnss/sirf.c
@@ -320,6 +320,11 @@ static int sirf_probe(struct serdev_device *serdev)
 	}
 
 	if (data->wakeup) {
+		ret = gpiod_get_value_cansleep(data->wakeup);
+		if (ret < 0)
+			goto err_disable_vcc;
+		data->active = ret;
+
 		ret = gpiod_to_irq(data->wakeup);
 		if (ret < 0)
 			goto err_disable_vcc;
@@ -332,6 +337,18 @@ static int sirf_probe(struct serdev_device *serdev)
 			goto err_disable_vcc;
 	}
 
+	if (data->on_off) {
+		/* Force hibernate mode if already active. */
+		if (data->active) {
+			ret = sirf_set_active(data, false);
+			if (ret) {
+				dev_err(dev, "failed to set hibernate mode: %d\n",
+						ret);
+				goto err_free_irq;
+			}
+		}
+	}
+
 	if (IS_ENABLED(CONFIG_PM)) {
 		pm_runtime_set_suspended(dev);	/* clear runtime_error flag */
 		pm_runtime_enable(dev);
-- 
2.20.1