From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thierry Reding Subject: Re: [PATCH v3 3/3] pwm: core: add consumer device link Date: Wed, 13 Feb 2019 13:53:53 +0100 Message-ID: <20190213125353.GI647@ulmo> References: <1550055012-23348-1-git-send-email-fabrice.gasnier@st.com> <1550055012-23348-4-git-send-email-fabrice.gasnier@st.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="jaTU8Y2VLE5tlY1O" Return-path: Content-Disposition: inline In-Reply-To: <1550055012-23348-4-git-send-email-fabrice.gasnier@st.com> Sender: linux-kernel-owner@vger.kernel.org To: Fabrice Gasnier Cc: robh+dt@kernel.org, u.kleine-koenig@pengutronix.de, tduszyns@gmail.com, mark.rutland@arm.com, alexandre.torgue@st.com, mcoquelin.stm32@gmail.com, devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-pwm@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com List-Id: devicetree@vger.kernel.org --jaTU8Y2VLE5tlY1O Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Feb 13, 2019 at 11:50:12AM +0100, Fabrice Gasnier wrote: > Add a device link between the PWM consumer and the PWM provider. This > enforces the PWM user to get suspended before the PWM provider. It > allows proper synchronization of suspend/resume sequences: the PWM user > is responsible for properly stopping PWM, before the provider gets > suspended: see [1]. Add the device link in: > - of_pwm_get() > - pwm_get() > - devm_ variants > as it requires a reference to the device for the PWM consumer. >=20 > [1] https://lkml.org/lkml/2019/2/5/770 >=20 > Suggested-by: Thierry Reding > Signed-off-by: Fabrice Gasnier > --- > Changes in v3: > - add struct device to of_get_pwm() arguments to handle device link from > there. > --- > drivers/pwm/core.c | 14 +++++++++++--- > include/linux/pwm.h | 6 ++++-- > 2 files changed, 15 insertions(+), 5 deletions(-) >=20 > diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c > index 1581f6a..8cb5d4bc 100644 > --- a/drivers/pwm/core.c > +++ b/drivers/pwm/core.c > @@ -638,6 +638,7 @@ static struct pwm_chip *of_node_to_pwmchip(struct dev= ice_node *np) > =20 > /** > * of_pwm_get() - request a PWM via the PWM framework > + * @dev: device for PWM consumer > * @np: device node to get the PWM from > * @con_id: consumer name > * > @@ -655,7 +656,8 @@ static struct pwm_chip *of_node_to_pwmchip(struct dev= ice_node *np) > * Returns: A pointer to the requested PWM device or an ERR_PTR()-encoded > * error code on failure. > */ > -struct pwm_device *of_pwm_get(struct device_node *np, const char *con_id) > +struct pwm_device *of_pwm_get(struct device *dev, struct device_node *np, > + const char *con_id) > { > struct pwm_device *pwm =3D NULL; > struct of_phandle_args args; > @@ -689,6 +691,9 @@ struct pwm_device *of_pwm_get(struct device_node *np,= const char *con_id) > if (IS_ERR(pwm)) > goto put; > =20 > + if (!device_link_add(dev, pwm->chip->dev, DL_FLAG_AUTOREMOVE_CONSUMER)) > + pr_debug("%s(): device link not added\n", __func__); I think it's better to turn this into dev_dbg(dev, ...) and maybe mention which supplier it failed to link to, something like: if (!device_link_add(...)) dev_dbg(dev, "failed to create device link to %s\n", pwm->chip->dev); Also, I wonder if this should perhaps be dev_err(). Under what circumstances does this fail? > + > /* > * If a consumer name was not given, try to look it up from the > * "pwm-names" property if it exists. Otherwise use the name of > @@ -771,7 +776,7 @@ struct pwm_device *pwm_get(struct device *dev, const = char *con_id) > =20 > /* look up via DT first */ > if (IS_ENABLED(CONFIG_OF) && dev && dev->of_node) > - return of_pwm_get(dev->of_node, con_id); > + return of_pwm_get(dev, dev->of_node, con_id); > =20 > /* > * We look up the provider in the static table typically provided by > @@ -851,6 +856,9 @@ struct pwm_device *pwm_get(struct device *dev, const = char *con_id) > pwm->args.period =3D chosen->period; > pwm->args.polarity =3D chosen->polarity; > =20 > + if (!device_link_add(dev, pwm->chip->dev, DL_FLAG_AUTOREMOVE_CONSUMER)) > + pr_debug("%s(): device link not added\n", __func__); Same here. Also: not sure if we really need to include __func__ in the message. > + > return pwm; > } > EXPORT_SYMBOL_GPL(pwm_get); > @@ -939,7 +947,7 @@ struct pwm_device *devm_of_pwm_get(struct device *dev= , struct device_node *np, > if (!ptr) > return ERR_PTR(-ENOMEM); > =20 > - pwm =3D of_pwm_get(np, con_id); > + pwm =3D of_pwm_get(dev, np, con_id); > if (!IS_ERR(pwm)) { > *ptr =3D pwm; > devres_add(dev, ptr); > diff --git a/include/linux/pwm.h b/include/linux/pwm.h > index d5199b5..895e074 100644 > --- a/include/linux/pwm.h > +++ b/include/linux/pwm.h > @@ -406,7 +406,8 @@ struct pwm_device *of_pwm_xlate_with_flags(struct pwm= _chip *pc, > const struct of_phandle_args *args); > =20 > struct pwm_device *pwm_get(struct device *dev, const char *con_id); > -struct pwm_device *of_pwm_get(struct device_node *np, const char *con_id= ); > +struct pwm_device *of_pwm_get(struct device *dev, struct device_node *np, > + const char *con_id); I'm slightly concerned about this. I think one of the reasons why this was introduced was to allow code to get at the PWM if they didn't have a struct device * available. However, it doesn't seem like there are any users of that function, so this seems fine. Thierry > void pwm_put(struct pwm_device *pwm); > =20 > struct pwm_device *devm_pwm_get(struct device *dev, const char *con_id); > @@ -494,7 +495,8 @@ static inline struct pwm_device *pwm_get(struct devic= e *dev, > return ERR_PTR(-ENODEV); > } > =20 > -static inline struct pwm_device *of_pwm_get(struct device_node *np, > +static inline struct pwm_device *of_pwm_get(struct device *dev, > + struct device_node *np, > const char *con_id) > { > return ERR_PTR(-ENODEV); > --=20 > 1.9.1 >=20 --jaTU8Y2VLE5tlY1O Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAABCAAdFiEEiOrDCAFJzPfAjcif3SOs138+s6EFAlxkE2EACgkQ3SOs138+ s6GFRw//WfjZ4WWaTh2RR5S6JcMl98NKiUpTDAtZrDp3x9nyj+mesyPf/U3BI5Sw cwccTz3axsu6UNGzSICWnFIFNFgkcprhzHSohDpTWfliLY9qDF2jGpE+GxnZlOmq /jC6fWdZLU364U3AoZSlRGb4EP4soclPdkRN4GOUhLrc/RkvsWgXF8FyO9Ey/5/R hZoLMgmsgoP200DcVFVcDp2ef43Q0NHKIvwxv2l7Khp1Yt+3jJ4QQkbijGbCLqNP bFROfS1ycHYk19bQcAhzpUWfxkU2ITZ9MnV9AX8CQIveO4ircvxqUiC8kplED7jf YOSz3+KNM72er/deev5gLOnmGF1RUM85PPCUbYDW9POHxdjRCyITyEix0zeTeDMc nW8s7qmaaAaVnKlDx4r2SPrj1/KrMUs82iODOp1ceRsGX6lSLckmIlaZyz1yYTqQ jRMUiu6bgb4YFODQ4LKLbZYicCmlTO1hXH9c7HbSmwiwk8Rl8t1i0qJctH2+hKct a5JGR7XmV0QsLgq6kBHB0eFAtfxY21iolcSI1A+I1bxRPyEe+p2vsDd78cO9X+4f 9ApI2rAGWxK7fdLIHBMPwixuDfTtjVps4ku2ZcP8Bkhijfx/Yt5efc0JN2dhdmZQ JmXhtskNozXeJvO3E9B86lr2Rgx8Ns79iNA15Ha17j3SpbDn8H0= =+1n7 -----END PGP SIGNATURE----- --jaTU8Y2VLE5tlY1O--