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authorGeert Uytterhoeven <geert+renesas@glider.be>2014-08-13 19:18:53 +0400
committerThierry Reding <thierry.reding@gmail.com>2014-08-18 12:58:43 +0400
commitd717ea73e36dd5659640fae82605ad85c4117f4d (patch)
tree2711ec749bf955f152b4852a0c4e11eb41726386 /drivers/pwm
parent7d1311b93e58ed55f3a31cc8f94c4b8fe988a2b9 (diff)
downloadlinux-d717ea73e36dd5659640fae82605ad85c4117f4d.tar.xz
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 <geert+renesas@glider.be> Cc: stable@vger.kernel.org Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
Diffstat (limited to 'drivers/pwm')
-rw-r--r--drivers/pwm/core.c8
1 files 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;