Linux-Hwmon Archive on lore.kernel.org
 help / color / Atom feed
From: Serge Semin <Sergey.Semin@baikalelectronics.ru>
To: Jean Delvare <jdelvare@suse.com>,
	Guenter Roeck <linux@roeck-us.net>,
	Maxim Kaurkin <maxim.kaurkin@baikalelectronics.ru>
Cc: Serge Semin <Sergey.Semin@baikalelectronics.ru>,
	Serge Semin <fancer.lancer@gmail.com>,
	Maxim Kaurkin <Maxim.Kaurkin@baikalelectronics.ru>,
	Alexey Malahov <Alexey.Malahov@baikalelectronics.ru>,
	Pavel Parkhomenko <Pavel.Parkhomenko@baikalelectronics.ru>,
	<linux-mips@vger.kernel.org>, <linux-hwmon@vger.kernel.org>,
	<linux-kernel@vger.kernel.org>
Subject: [PATCH 3/3] hwmon: bt1-pvt: Wait for the completion with timeout
Date: Sun, 20 Sep 2020 14:09:23 +0300
Message-ID: <20200920110924.19741-4-Sergey.Semin@baikalelectronics.ru> (raw)
In-Reply-To: <20200920110924.19741-1-Sergey.Semin@baikalelectronics.ru>

If the PVT sensor is suddenly powered down while a caller is waiting for
the conversion completion, the request won't be finished and the task will
hang up on this procedure until the power is back up again. Let's call the
wait_for_completion_timeout() method instead to prevent that. The cached
timeout is exactly what we need to predict for how long conversion could
normally last.

Fixes: 87976ce2825d ("hwmon: Add Baikal-T1 PVT sensor driver")
Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
---
 drivers/hwmon/bt1-pvt.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/hwmon/bt1-pvt.c b/drivers/hwmon/bt1-pvt.c
index 2600426a3b21..3e1d56585b91 100644
--- a/drivers/hwmon/bt1-pvt.c
+++ b/drivers/hwmon/bt1-pvt.c
@@ -477,6 +477,7 @@ static int pvt_read_data(struct pvt_hwmon *pvt, enum pvt_sensor_type type,
 			 long *val)
 {
 	struct pvt_cache *cache = &pvt->cache[type];
+	unsigned long timeout;
 	u32 data;
 	int ret;
 
@@ -500,7 +501,14 @@ static int pvt_read_data(struct pvt_hwmon *pvt, enum pvt_sensor_type type,
 	pvt_update(pvt->regs + PVT_INTR_MASK, PVT_INTR_DVALID, 0);
 	pvt_update(pvt->regs + PVT_CTRL, PVT_CTRL_EN, PVT_CTRL_EN);
 
-	wait_for_completion(&cache->conversion);
+	/*
+	 * Wait with timeout since in case if the sensor is suddenly powered
+	 * down the request won't be completed and the caller will hang up on
+	 * this procedure until the power is back up again. Multiply the
+	 * timeout by the factor of two to prevent a false timeout.
+	 */
+	timeout = 2 * usecs_to_jiffies(ktime_to_us(pvt->timeout));
+	ret = wait_for_completion_timeout(&cache->conversion, timeout);
 
 	pvt_update(pvt->regs + PVT_CTRL, PVT_CTRL_EN, 0);
 	pvt_update(pvt->regs + PVT_INTR_MASK, PVT_INTR_DVALID,
@@ -510,6 +518,9 @@ static int pvt_read_data(struct pvt_hwmon *pvt, enum pvt_sensor_type type,
 
 	mutex_unlock(&pvt->iface_mtx);
 
+	if (!ret)
+		return -ETIMEDOUT;
+
 	if (type == PVT_TEMP)
 		*val = pvt_calc_poly(&poly_N_to_temp, data);
 	else
-- 
2.27.0


  parent reply index

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-20 11:09 [PATCH 0/3] hwmon: bt1-pvt: Fix PVT sensor being unpowered Serge Semin
2020-09-20 11:09 ` [PATCH 1/3] hwmon: bt1-pvt: Test sensor power supply on probe Serge Semin
2020-10-02 16:15   ` Guenter Roeck
2020-09-20 11:09 ` [PATCH 2/3] hwmon: bt1-pvt: Cache current update timeout Serge Semin
2020-10-02 16:15   ` Guenter Roeck
2020-09-20 11:09 ` Serge Semin [this message]
2020-10-02 16:15   ` [PATCH 3/3] hwmon: bt1-pvt: Wait for the completion with timeout Guenter Roeck

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20200920110924.19741-4-Sergey.Semin@baikalelectronics.ru \
    --to=sergey.semin@baikalelectronics.ru \
    --cc=Alexey.Malahov@baikalelectronics.ru \
    --cc=Pavel.Parkhomenko@baikalelectronics.ru \
    --cc=fancer.lancer@gmail.com \
    --cc=jdelvare@suse.com \
    --cc=linux-hwmon@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mips@vger.kernel.org \
    --cc=linux@roeck-us.net \
    --cc=maxim.kaurkin@baikalelectronics.ru \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-Hwmon Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-hwmon/0 linux-hwmon/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-hwmon linux-hwmon/ https://lore.kernel.org/linux-hwmon \
		linux-hwmon@vger.kernel.org
	public-inbox-index linux-hwmon

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-hwmon


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git