From mboxrd@z Thu Jan 1 00:00:00 1970 From: boris.brezillon@free-electrons.com (Boris Brezillon) Date: Tue, 17 May 2016 14:08:03 +0200 Subject: [PATCH] pwm: atmel-hlcdc: Fix default PWM polarity In-Reply-To: <20160517110005.GA26166@ulmo.ba.sec> References: <1463476352-7485-1-git-send-email-boris.brezillon@free-electrons.com> <20160517110005.GA26166@ulmo.ba.sec> Message-ID: <20160517140803.078e3f5e@bbrezillon> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi Thierry, On Tue, 17 May 2016 13:00:05 +0200 Thierry Reding wrote: > On Tue, May 17, 2016 at 11:12:32AM +0200, Boris Brezillon wrote: > > The PWM device exposed by the HLCDC IP is configured with an inverted > > polarity by default. Registering the PWM chip with the normal polarity > > was not a problem before commit 42e8992c58d4 ("pwm: Add core > > infrastructure to allow atomic updates") because the ->set_polarity() > > hook was called no matter the current polarity state, but this is no longer > > the case. > > > > Signed-off-by: Boris Brezillon > > Fixes: 42e8992c58d4 ("pwm: Add core infrastructure to allow atomic updates") > > That's not technically correct, because it's the driver that has the > bug. The core change merely exposes it. How about if I sort this into > the pwm-atomic branch and reword the commit message accordingly? That > way things should all stay bisectible. > > Then again, given the breakage caused by the pwm_args patch I suppose > it doesn't matter much because that's part of a stable branch that I > can't rebase. If I understood correctly, you plan to rebase your pwm-atomic branch to insert this commit before commit 42e8992c58d4 ("pwm: Add core infrastructure to allow atomic updates"). Could you consider taking the following commit (or something similar if you already have a fix) as the first commit of your pwm-atomic branch? Sorry for the mess around the introduction of pwm_args and pwm_state (that's not an excuse, but I've reworked this series so many time that I forgot to check bisectibility on the last versions :-(). --- >>From ad73fa3a56c7320979425d64ab54c09b9d83d4cf Mon Sep 17 00:00:00 2001 From: Boris Brezillon Date: Tue, 17 May 2016 13:55:02 +0200 Subject: [PATCH] pwm: Fix pwm_apply_args() call sites pwm_apply_args() is supposed to initialize a PWM device according to the arguments provided by the DT or the PWM lookup, but this function was called inside pwm_device_request(), which in turn was called before the core had a chance to initialize the pwm->args fields. Fix that by calling pwm_apply_args directly in pwm_get() and of_pwm_get() after initializing pwm->args field. This commit also fixes an invalid pointer dereference introduced by commit e39c0df1be5a ("pwm: Introduce the pwm_args concept"). Signed-off-by: Boris Brezillon Fixes: e39c0df1be5a ("pwm: Introduce the pwm_args concept") --- drivers/pwm/core.c | 27 +++++++++++++++++---------- 1 file changed, 17 insertions(+), 10 deletions(-) diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c index 680fbc7..22cf395 100644 --- a/drivers/pwm/core.c +++ b/drivers/pwm/core.c @@ -128,13 +128,6 @@ static int pwm_device_request(struct pwm_device *pwm, const char *label) set_bit(PWMF_REQUESTED, &pwm->flags); pwm->label = label; - /* - * FIXME: This should be removed once all PWM users properly make use - * of struct pwm_args to initialize the PWM device. As long as this is - * here, the PWM state and hardware state can get out of sync. - */ - pwm_apply_args(pwm); - return 0; } @@ -627,6 +620,13 @@ struct pwm_device *of_pwm_get(struct device_node *np, const char *con_id) pwm->label = con_id; + /* + * FIXME: This should be removed once all PWM users properly make use + * of struct pwm_args to initialize the PWM device. As long as this is + * here, the PWM state and hardware state can get out of sync. + */ + pwm_apply_args(pwm); + put: of_node_put(args.np); @@ -754,13 +754,20 @@ struct pwm_device *pwm_get(struct device *dev, const char *con_id) if (!chip) goto out; - pwm->args.period = chosen->period; - pwm->args.polarity = chosen->polarity; - pwm = pwm_request_from_chip(chip, chosen->index, con_id ?: dev_id); if (IS_ERR(pwm)) goto out; + pwm->args.period = chosen->period; + pwm->args.polarity = chosen->polarity; + + /* + * FIXME: This should be removed once all PWM users properly make use + * of struct pwm_args to initialize the PWM device. As long as this is + * here, the PWM state and hardware state can get out of sync. + */ + pwm_apply_args(pwm); + out: mutex_unlock(&pwm_lookup_lock); return pwm;