From: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de> To: Lee Jones <lee.jones@linaro.org>, Michael Walle <michael@walle.cc>, Thierry Reding <thierry.reding@gmail.com> Cc: linux-pwm@vger.kernel.org, kernel@pengutronix.de Subject: [PATCH] pwm: sl28cpld: fix getting driver data in pwm callbacks Date: Tue, 24 Nov 2020 22:24:32 +0100 [thread overview] Message-ID: <20201124212432.3117322-1-u.kleine-koenig@pengutronix.de> (raw) Currently .get_state() and .apply() use dev_get_drvdata() on the struct device related to the pwm chip. This only works after .probe() called platform_set_drvdata() which in this driver happens only after pwmchip_add() and so comes possibly too late. Instead of setting the driver data earlier use the traditional container_of approach as this way the driver data is conceptually and computational nearer. Fixes: 9db33d221efc ("pwm: Add support for sl28cpld PWM controller") Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> --- Hello, in v4 of the driver Michael still used container_of and then changed to use dev_get_drvdata() as Lee suggested. I didn't notice this suggestion, otherwise I would have expressed my variance about this already earlier. I noticed this problem because Michael contacted me via irc and showed me the resulting oops, so I think applying this before 5.10 would be good. It's not entirely clear to me why .get_state() is called that early in his case, but the theory is clear: The callbacks can be called as soon as pwmchip_add() is called. Best regards Uwe drivers/pwm/pwm-sl28cpld.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/pwm/pwm-sl28cpld.c b/drivers/pwm/pwm-sl28cpld.c index 5046b6b7fd35..b4c651fc749c 100644 --- a/drivers/pwm/pwm-sl28cpld.c +++ b/drivers/pwm/pwm-sl28cpld.c @@ -84,12 +84,14 @@ struct sl28cpld_pwm { struct regmap *regmap; u32 offset; }; +#define sl28cpld_pwm_from_chip(_chip) \ + container_of(_chip, struct sl28cpld_pwm, pwm_chip) static void sl28cpld_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm, struct pwm_state *state) { - struct sl28cpld_pwm *priv = dev_get_drvdata(chip->dev); + struct sl28cpld_pwm *priv = sl28cpld_pwm_from_chip(chip); unsigned int reg; int prescaler; @@ -118,7 +120,7 @@ static void sl28cpld_pwm_get_state(struct pwm_chip *chip, static int sl28cpld_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, const struct pwm_state *state) { - struct sl28cpld_pwm *priv = dev_get_drvdata(chip->dev); + struct sl28cpld_pwm *priv = sl28cpld_pwm_from_chip(chip); unsigned int cycle, prescaler; bool write_duty_cycle_first; int ret; -- 2.29.2
next reply other threads:[~2020-11-24 21:25 UTC|newest] Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-11-24 21:24 Uwe Kleine-König [this message] 2020-11-24 22:22 ` Michael Walle 2020-11-25 6:48 ` Uwe Kleine-König 2020-11-30 8:17 ` Michael Walle 2020-11-30 14:58 ` Uwe Kleine-König
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