From d717ea73e36dd5659640fae82605ad85c4117f4d Mon Sep 17 00:00:00 2001 From: Geert Uytterhoeven Date: Wed, 13 Aug 2014 17:18:53 +0200 Subject: [PATCH] pwm: Fix period and polarity in pwm_get() for non-perfect matches If pwm_get() finds a look-up entry with a perfect match (both dev_id and con_id match), the loop is aborted, and "p" still points to the correct struct pwm_lookup. If only an entry with a matching dev_id or con_id is found, the loop terminates after traversing the whole list, and "p" now points to arbitrary memory, not part of the pwm_lookup list. Then pwm_set_period() and pwm_set_polarity() will set random values for period resp. polarity. To fix this, save period and polarity when finding a new best match, just like is done for chip (for the provider) and index. This fixes the LCD backlight on r8a7740/armadillo-legacy, which was fed period 0 and polarity -1068821144 instead of 33333 resp. 1. Fixes: 3796ce1d4d4b ("pwm: add period and polarity to struct pwm_lookup") Signed-off-by: Geert Uytterhoeven Cc: stable@vger.kernel.org Signed-off-by: Thierry Reding --- drivers/pwm/core.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c index 4b66bf09ee55..d2c35920ff08 100644 --- a/drivers/pwm/core.c +++ b/drivers/pwm/core.c @@ -606,6 +606,8 @@ struct pwm_device *pwm_get(struct device *dev, const char *con_id) unsigned int best = 0; struct pwm_lookup *p; unsigned int match; + unsigned int period; + enum pwm_polarity polarity; /* look up via DT first */ if (IS_ENABLED(CONFIG_OF) && dev && dev->of_node) @@ -653,6 +655,8 @@ struct pwm_device *pwm_get(struct device *dev, const char *con_id) if (match > best) { chip = pwmchip_find_by_name(p->provider); index = p->index; + period = p->period; + polarity = p->polarity; if (match != 3) best = match; @@ -668,8 +672,8 @@ struct pwm_device *pwm_get(struct device *dev, const char *con_id) if (IS_ERR(pwm)) return pwm; - pwm_set_period(pwm, p->period); - pwm_set_polarity(pwm, p->polarity); + pwm_set_period(pwm, period); + pwm_set_polarity(pwm, polarity); return pwm;