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From:   Miaoqian Lin <linmq006@gmail.com>
To:     Jonathan Cameron <jic23@kernel.org>,
        Lars-Peter Clausen <lars@metafoo.de>,
        Maxime Coquelin <mcoquelin.stm32@gmail.com>,
        Alexandre Torgue <alexandre.torgue@foss.st.com>,
        Miaoqian Lin <linmq006@gmail.com>,
        Kees Cook <keescook@chromium.org>,
        Philippe Schenker <philippe.schenker@toradex.com>,
        linux-iio@vger.kernel.org,
        linux-stm32@st-md-mailman.stormreply.com,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: [PATCH v3] iio: adc: stmpe-adc: Fix wait_for_completion_timeout return value check
Date:   Tue, 12 Apr 2022 06:51:45 +0000
Message-Id: <20220412065150.14486-1-linmq006@gmail.com>
In-Reply-To: <PH0PR03MB6786157EDA63137DF0071D1F99ED9@PH0PR03MB6786.namprd03.prod.outlook.com>
References: <PH0PR03MB6786157EDA63137DF0071D1F99ED9@PH0PR03MB6786.namprd03.prod.outlook.com>
Precedence: bulk

wait_for_completion_timeout() returns unsigned long not long.
it returns 0 if timed out, and positive if completed.
The check for <= 0 is ambiguous and should be == 0 here
indicating timeout which is the only error case

Fixes: e813dde6f833 ("iio: stmpe-adc: Use wait_for_completion_timeout")
Signed-off-by: Miaoqian Lin <linmq006@gmail.com>
---
changes in v2:
- Fix same issue in stmpe_read_temp.
---
changes in v3:
- update the patch subject.
---
 drivers/iio/adc/stmpe-adc.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/iio/adc/stmpe-adc.c b/drivers/iio/adc/stmpe-adc.c
index d2d405388499..83e0ac4467ca 100644
--- a/drivers/iio/adc/stmpe-adc.c
+++ b/drivers/iio/adc/stmpe-adc.c
@@ -61,7 +61,7 @@ struct stmpe_adc {
 static int stmpe_read_voltage(struct stmpe_adc *info,
 		struct iio_chan_spec const *chan, int *val)
 {
-	long ret;
+	unsigned long ret;
 
 	mutex_lock(&info->lock);
 
@@ -79,7 +79,7 @@ static int stmpe_read_voltage(struct stmpe_adc *info,
 
 	ret = wait_for_completion_timeout(&info->completion, STMPE_ADC_TIMEOUT);
 
-	if (ret <= 0) {
+	if (ret == 0) {
 		stmpe_reg_write(info->stmpe, STMPE_REG_ADC_INT_STA,
 				STMPE_ADC_CH(info->channel));
 		mutex_unlock(&info->lock);
@@ -96,7 +96,7 @@ static int stmpe_read_voltage(struct stmpe_adc *info,
 static int stmpe_read_temp(struct stmpe_adc *info,
 		struct iio_chan_spec const *chan, int *val)
 {
-	long ret;
+	unsigned long ret;
 
 	mutex_lock(&info->lock);
 
@@ -114,7 +114,7 @@ static int stmpe_read_temp(struct stmpe_adc *info,
 
 	ret = wait_for_completion_timeout(&info->completion, STMPE_ADC_TIMEOUT);
 
-	if (ret <= 0) {
+	if (ret == 0) {
 		mutex_unlock(&info->lock);
 		return -ETIMEDOUT;
 	}
-- 
2.17.1