From: Dan Carpenter <dan.carpenter@linaro.org>
To: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
Cc: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>,
Alim Akhtar <alim.akhtar@samsung.com>,
Thierry Reding <thierry.reding@gmail.com>,
linux-arm-kernel@lists.infradead.org,
linux-samsung-soc@vger.kernel.org, linux-pwm@vger.kernel.org,
kernel-janitors@vger.kernel.org
Subject: [PATCH] pwm: samsung: Fix a bit test
Date: Tue, 17 Oct 2023 17:04:08 +0300 [thread overview]
Message-ID: <917e3890-7895-4b1c-bcee-4eecb3b7fe09@moroto.mountain> (raw)
This code has two problems. First, it passes the wrong bit parameter to
test_bit(). Second, it mixes using PWMF_REQUESTED in test_bit() and in
open coded bit tests.
The test_bit() function takes a bit number. In other words,
"if (test_bit(0, &flags))" is the equivalent of "if (flags & (1 << 0))".
Passing (1 << 0) to test_bit() is like writing BIT(BIT(0)). It's a
double shift bug.
In pwm_samsung_resume() these issues mean that the flag is never set and
the function is essentially a no-op.
Fixes: 4c9548d24c0d ("pwm: samsung: Put per-channel data into driver data")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
---
From static analysis and not tested.
drivers/pwm/pwm-samsung.c | 2 +-
include/linux/pwm.h | 4 ++--
2 files changed, 3 insertions(+), 3 deletions(-)
diff --git a/drivers/pwm/pwm-samsung.c b/drivers/pwm/pwm-samsung.c
index 10fe2c13cd80..acf4a0d8d990 100644
--- a/drivers/pwm/pwm-samsung.c
+++ b/drivers/pwm/pwm-samsung.c
@@ -630,7 +630,7 @@ static int pwm_samsung_resume(struct device *dev)
struct pwm_device *pwm = &chip->pwms[i];
struct samsung_pwm_channel *chan = &our_chip->channel[i];
- if (!(pwm->flags & PWMF_REQUESTED))
+ if (!test_bit(PWMF_REQUESTED, &pwm->flags))
continue;
if (our_chip->variant.output_mask & BIT(i))
diff --git a/include/linux/pwm.h b/include/linux/pwm.h
index e3b437587b32..3eee5bf367fb 100644
--- a/include/linux/pwm.h
+++ b/include/linux/pwm.h
@@ -41,8 +41,8 @@ struct pwm_args {
};
enum {
- PWMF_REQUESTED = 1 << 0,
- PWMF_EXPORTED = 1 << 1,
+ PWMF_REQUESTED = 0,
+ PWMF_EXPORTED = 1,
};
/*
--
2.39.2
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next reply other threads:[~2023-10-17 14:04 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-17 14:04 Dan Carpenter [this message]
2023-10-24 21:11 ` [PATCH] pwm: samsung: Fix a bit test Uwe Kleine-König
2023-10-25 4:18 ` Dan Carpenter
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