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| author | Geert Uytterhoeven <geert+renesas@glider.be> | 2014-08-13 17:18:53 +0200 |
|---|---|---|
| committer | Thierry Reding <thierry.reding@gmail.com> | 2014-08-18 10:58:43 +0200 |
| commit | d717ea73e36dd5659640fae82605ad85c4117f4d (patch) | |
| tree | 2711ec749bf955f152b4852a0c4e11eb41726386 /drivers/pwm | |
| parent | 7d1311b93e58ed55f3a31cc8f94c4b8fe988a2b9 (diff) | |
| download | linux-stable-d717ea73e36dd5659640fae82605ad85c4117f4d.tar.gz linux-stable-d717ea73e36dd5659640fae82605ad85c4117f4d.tar.bz2 linux-stable-d717ea73e36dd5659640fae82605ad85c4117f4d.zip | |
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.c | 8 |
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; |