Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934258AbcJMFyq (ORCPT ); Thu, 13 Oct 2016 01:54:46 -0400 Received: from mo178.mail-out.ovh.net ([178.32.228.178]:44193 "EHLO mo178.mail-out.ovh.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755215AbcJMFyc (ORCPT ); Thu, 13 Oct 2016 01:54:32 -0400 Date: Thu, 13 Oct 2016 06:58:12 +0200 From: Lukasz Majewski To: Stefan Agner Cc: Bhuvanchandra DV , shawnguo@kernel.org, thierry.reding@gmail.com, robh+dt@kernel.org, mark.rutland@arm.com, kernel@pengutronix.de, fabio.estevam@nxp.com, linux-pwm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Lothar Wassmann , boris.brezillon@free-electrons.com Subject: Re: [PATCH v3 3/6] pwm: imx: support output polarity inversion Message-ID: <20161013065812.0da91859@jawa> In-Reply-To: References: <20161007151129.6043-1-bhuvanchandra.dv@toradex.com> <20161007151129.6043-4-bhuvanchandra.dv@toradex.com> <5325a332099473a2d8382530f79c5a8e@agner.ch> <20161013001540.7f759158@jawa> X-Mailer: Claws Mail 3.11.1 (GTK+ 2.24.25; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; boundary="Sig_/zZgYt1EnnBs93JD5xfb7+3L"; protocol="application/pgp-signature" X-Ovh-Tracer-Id: 1475773304896078407 X-VR-SPAMSTATE: OK X-VR-SPAMSCORE: -100 X-VR-SPAMCAUSE: gggruggvucftvghtrhhoucdtuddrfeelvddrgeefgdelfecutefuodetggdotefrodftvfcurfhrohhfihhlvgemucfqggfjnecuuegrihhlohhuthemuceftddtnecusecvtfgvtghiphhivghnthhsucdlqddutddtmd Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 8935 Lines: 266 --Sig_/zZgYt1EnnBs93JD5xfb7+3L Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Hi Stefan, > On 2016-10-12 15:15, Lukasz Majewski wrote: > > Hi Stefan, > >=20 > >> On 2016-10-07 08:11, Bhuvanchandra DV wrote: > >> > From: Lothar Wassmann > >> > > >> > The i.MX pwm unit on i.MX27 and newer SoCs provides a > >> > configurable output polarity. This patch adds support to utilize > >> > this feature where available. > >> > > >> > Signed-off-by: Lothar Wa=C3=9Fmann > >> > Signed-off-by: Lukasz Majewski > >> > Signed-off-by: Bhuvanchandra DV > >> > Acked-by: Shawn Guo > >> > Reviewed-by: Sascha Hauer > >> > --- > >> > Documentation/devicetree/bindings/pwm/imx-pwm.txt | 6 +-- > >> > drivers/pwm/pwm-imx.c | 51 > >> > +++++++++++++++++++++-- 2 files changed, 51 insertions(+), 6 > >> > deletions(-) > >> > > >> > diff --git a/Documentation/devicetree/bindings/pwm/imx-pwm.txt > >> > b/Documentation/devicetree/bindings/pwm/imx-pwm.txt > >> > index e00c2e9..c61bdf8 100644 > >> > --- a/Documentation/devicetree/bindings/pwm/imx-pwm.txt > >> > +++ b/Documentation/devicetree/bindings/pwm/imx-pwm.txt > >> > @@ -6,8 +6,8 @@ Required properties: > >> > - "fsl,imx1-pwm" for PWM compatible with the one integrated on > >> > i.MX1 > >> > - "fsl,imx27-pwm" for PWM compatible with the one integrated > >> > on i.MX27 > >> > - reg: physical base address and length of the controller's > >> > registers -- #pwm-cells: should be 2. See pwm.txt in this > >> > directory for a description of > >> > - the cells format. > >> > +- #pwm-cells: 2 for i.MX1 and 3 for i.MX27 and newer SoCs. See > >> > pwm.txt > >> > + in this directory for a description of the cells format. > >> > - clocks : Clock specifiers for both ipg and per clocks. > >> > - clock-names : Clock names should include both "ipg" and "per" > >> > See the clock consumer binding, > >> > @@ -17,7 +17,7 @@ See the clock consumer binding, > >> > Example: > >> > > >> > pwm1: pwm@53fb4000 { > >> > - #pwm-cells =3D <2>; > >> > + #pwm-cells =3D <3>; > >> > compatible =3D "fsl,imx53-pwm", "fsl,imx27-pwm"; > >> > reg =3D <0x53fb4000 0x4000>; > >> > clocks =3D <&clks IMX5_CLK_PWM1_IPG_GATE>, > >> > diff --git a/drivers/pwm/pwm-imx.c b/drivers/pwm/pwm-imx.c > >> > index d600fd5..c37d223 100644 > >> > --- a/drivers/pwm/pwm-imx.c > >> > +++ b/drivers/pwm/pwm-imx.c > >> > @@ -38,6 +38,7 @@ > >> > #define MX3_PWMCR_DOZEEN (1 << 24) > >> > #define MX3_PWMCR_WAITEN (1 << 23) > >> > #define MX3_PWMCR_DBGEN (1 << 22) > >> > +#define MX3_PWMCR_POUTC (1 << 18) > >> > #define MX3_PWMCR_CLKSRC_IPG_HIGH (2 << 16) > >> > #define MX3_PWMCR_CLKSRC_IPG (1 << 16) > >> > #define MX3_PWMCR_SWR (1 << 3) > >> > @@ -180,6 +181,9 @@ static int imx_pwm_config_v2(struct pwm_chip > >> > *chip, if (enable) > >> > cr |=3D MX3_PWMCR_EN; > >> > > >> > + if (pwm->args.polarity =3D=3D PWM_POLARITY_INVERSED) > >> > + cr |=3D MX3_PWMCR_POUTC; > >> > + > >> > >> This seems wrong to me, the config callback is meant for > >> period/duty cycle only. > >=20 > > If it is meant only for that, then the polarity should be removed > > from it. > >=20 > > However after very quick testing, at least on my setup, it turns out > > that removing this lines causes polarity to _not_ being set (and the > > polarity is not inverted). > >=20 > > I will investigate this further on my setup and hopefully sent > > proper patch. > >=20 > >> The set_polarity callback should get called in case a > >> different polarity is requested. > >=20 > > On my setup the pwm2 is set from DT and pwm_backlight_probe() calls > > pwm_apply_args(), so everything should work. However, as I mentioned > > above there still is some problem with inversion setting. > >=20 > >> > >> > >> > writel(cr, imx->mmio_base + MX3_PWMCR); > >> > > >> > return 0; > >> > @@ -240,27 +244,62 @@ static void imx_pwm_disable(struct pwm_chip > >> > *chip, struct pwm_device *pwm) > >> > clk_disable_unprepare(imx->clk_per); > >> > } > >> > > >> > -static struct pwm_ops imx_pwm_ops =3D { > >> > +static int imx_pwm_set_polarity(struct pwm_chip *chip, struct > >> > pwm_device *pwm, > >> > + enum pwm_polarity polarity) > >> > +{ > >> > + struct imx_chip *imx =3D to_imx_chip(chip); > >> > + u32 val; > >> > + > >> > + if (polarity =3D=3D pwm->args.polarity) > >> > + return 0; > >> > >> I don't think that this is right. Today, pwm_apply_args (in > >> include/linux/pwm.h) copies the polarity from args to > >> state.polarity, which is then passed as polarity argument to this > >> function. So this will always return 0 afaict. > >=20 > > Yes, I've overlooked it (that the state is copied). > >=20 > > It can be dropped. >=20 > Did you do the above test with that line dropped? Yes. The above code has been also removed. Best regards, =C5=81ukasz Majewski >=20 > >=20 > >> > >> I would just drop that. > >> > >> There is probably one little problem in the current state of > >> affairs: If the bootloader makes use of a PWM channel with > >> inverted state, then the kernel would not know about that and > >> currently assume a wrong initial state... I guess at one point in > >> time we should implement the state retrieval callback and move to > >> the new atomic PWM API, which would mean to implement apply > >> callback. > >=20 > > Are there any patches on the horizon? > >=20 >=20 > Not that I know of... >=20 > -- > Stefan >=20 > >> > >> -- > >> Stefan > >> > >> > >> > + > >> > + val =3D readl(imx->mmio_base + MX3_PWMCR); > >> > + > >> > + if (polarity =3D=3D PWM_POLARITY_INVERSED) > >> > + val |=3D MX3_PWMCR_POUTC; > >> > + else > >> > + val &=3D ~MX3_PWMCR_POUTC; > >> > + > >> > + writel(val, imx->mmio_base + MX3_PWMCR); > >> > + > >> > + dev_dbg(imx->chip.dev, "%s: polarity set to %s\n", > >> > __func__, > >> > + polarity =3D=3D PWM_POLARITY_INVERSED ? "inverted" : > >> > "normal"); + > >> > + return 0; > >> > +} > >> > + > >> > +static struct pwm_ops imx_pwm_ops_v1 =3D { > >> > .enable =3D imx_pwm_enable, > >> > .disable =3D imx_pwm_disable, > >> > .config =3D imx_pwm_config, > >> > .owner =3D THIS_MODULE, > >> > }; > >> > > >> > +static struct pwm_ops imx_pwm_ops_v2 =3D { > >> > + .enable =3D imx_pwm_enable, > >> > + .disable =3D imx_pwm_disable, > >> > + .set_polarity =3D imx_pwm_set_polarity, > >> > + .config =3D imx_pwm_config, > >> > + .owner =3D THIS_MODULE, > >> > +}; > >> > + > >> > struct imx_pwm_data { > >> > int (*config)(struct pwm_chip *chip, > >> > struct pwm_device *pwm, int duty_ns, int > >> > period_ns); void (*set_enable)(struct pwm_chip *chip, bool > >> > enable); > >> > + struct pwm_ops *pwm_ops; > >> > }; > >> > > >> > static struct imx_pwm_data imx_pwm_data_v1 =3D { > >> > .config =3D imx_pwm_config_v1, > >> > .set_enable =3D imx_pwm_set_enable_v1, > >> > + .pwm_ops =3D &imx_pwm_ops_v1, > >> > }; > >> > > >> > static struct imx_pwm_data imx_pwm_data_v2 =3D { > >> > .config =3D imx_pwm_config_v2, > >> > .set_enable =3D imx_pwm_set_enable_v2, > >> > + .pwm_ops =3D &imx_pwm_ops_v2, > >> > }; > >> > > >> > static const struct of_device_id imx_pwm_dt_ids[] =3D { > >> > @@ -282,6 +321,8 @@ static int imx_pwm_probe(struct > >> > platform_device *pdev) if (!of_id) > >> > return -ENODEV; > >> > > >> > + data =3D of_id->data; > >> > + > >> > imx =3D devm_kzalloc(&pdev->dev, sizeof(*imx), > >> > GFP_KERNEL); if (imx =3D=3D NULL) > >> > return -ENOMEM; > >> > @@ -300,18 +341,22 @@ static int imx_pwm_probe(struct > >> > platform_device *pdev) return PTR_ERR(imx->clk_ipg); > >> > } > >> > > >> > - imx->chip.ops =3D &imx_pwm_ops; > >> > + imx->chip.ops =3D data->pwm_ops; > >> > imx->chip.dev =3D &pdev->dev; > >> > imx->chip.base =3D -1; > >> > imx->chip.npwm =3D 1; > >> > imx->chip.can_sleep =3D true; > >> > + if (data->pwm_ops->set_polarity) { > >> > + dev_dbg(&pdev->dev, "PWM supports output > >> > inversion\n"); > >> > + imx->chip.of_xlate =3D of_pwm_xlate_with_flags; > >> > + imx->chip.of_pwm_n_cells =3D 3; > >> > + } > >> > > >> > r =3D platform_get_resource(pdev, IORESOURCE_MEM, 0); > >> > imx->mmio_base =3D devm_ioremap_resource(&pdev->dev, r); > >> > if (IS_ERR(imx->mmio_base)) > >> > return PTR_ERR(imx->mmio_base); > >> > > >> > - data =3D of_id->data; > >> > imx->config =3D data->config; > >> > imx->set_enable =3D data->set_enable; > >> > >=20 > > Best regards, > >=20 > > =C5=81ukasz Majewski --Sig_/zZgYt1EnnBs93JD5xfb7+3L Content-Type: application/pgp-signature Content-Description: OpenPGP digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iEYEARECAAYFAlf/FGsACgkQf9/hG2YwgjFRDACfWKTs1fizQv11GaROZoL2hNGa ZisAn08iz//PakpkSYJi2OCAIaBiZHM5 =bWCK -----END PGP SIGNATURE----- --Sig_/zZgYt1EnnBs93JD5xfb7+3L--