Hi Stefan, > On 2016-10-12 15:15, Lukasz Majewski wrote: > > Hi Stefan, > > > >> On 2016-10-07 08:11, Bhuvanchandra DV wrote: > >> > From: Lothar Wassmann <[email protected]> > >> > > >> > 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 Waßmann <[email protected]> > >> > Signed-off-by: Lukasz Majewski <[email protected]> > >> > Signed-off-by: Bhuvanchandra DV <[email protected]> > >> > Acked-by: Shawn Guo <[email protected]> > >> > Reviewed-by: Sascha Hauer <[email protected]> > >> > --- > >> > 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 = <2>; > >> > + #pwm-cells = <3>; > >> > compatible = "fsl,imx53-pwm", "fsl,imx27-pwm"; > >> > reg = <0x53fb4000 0x4000>; > >> > clocks = <&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 |= MX3_PWMCR_EN; > >> > > >> > + if (pwm->args.polarity == PWM_POLARITY_INVERSED) > >> > + cr |= MX3_PWMCR_POUTC; > >> > + > >> > >> This seems wrong to me, the config callback is meant for > >> period/duty cycle only. > > > > If it is meant only for that, then the polarity should be removed > > from it. > > > > 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). > > > > I will investigate this further on my setup and hopefully sent > > proper patch. > > > >> The set_polarity callback should get called in case a > >> different polarity is requested. > > > > 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. > > > >> > >> > >> > 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 = { > >> > +static int imx_pwm_set_polarity(struct pwm_chip *chip, struct > >> > pwm_device *pwm, > >> > + enum pwm_polarity polarity) > >> > +{ > >> > + struct imx_chip *imx = to_imx_chip(chip); > >> > + u32 val; > >> > + > >> > + if (polarity == 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. > > > > Yes, I've overlooked it (that the state is copied). > > > > It can be dropped. > > Did you do the above test with that line dropped?
Yes. The above code has been also removed.
Best regards,
Łukasz Majewski
>
> >
> >>
> >> 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.
> >
> > Are there any patches on the horizon?
> >
>
> Not that I know of...
>
> --
> Stefan
>
> >>
> >> --
> >> Stefan
> >>
> >>
> >> > +
> >> > + val = readl(imx->mmio_base + MX3_PWMCR);
> >> > +
> >> > + if (polarity == PWM_POLARITY_INVERSED)
> >> > + val |= MX3_PWMCR_POUTC;
> >> > + else
> >> > + val &= ~MX3_PWMCR_POUTC;
> >> > +
> >> > + writel(val, imx->mmio_base + MX3_PWMCR);
> >> > +
> >> > + dev_dbg(imx->chip.dev, "%s: polarity set to %s\n",
> >> > __func__,
> >> > + polarity == PWM_POLARITY_INVERSED ? "inverted" :
> >> > "normal"); +
> >> > + return 0;
> >> > +}
> >> > +
> >> > +static struct pwm_ops imx_pwm_ops_v1 = {
> >> > .enable = imx_pwm_enable,
> >> > .disable = imx_pwm_disable,
> >> > .config = imx_pwm_config,
> >> > .owner = THIS_MODULE,
> >> > };
> >> >
> >> > +static struct pwm_ops imx_pwm_ops_v2 = {
> >> > + .enable = imx_pwm_enable,
> >> > + .disable = imx_pwm_disable,
> >> > + .set_polarity = imx_pwm_set_polarity,
> >> > + .config = imx_pwm_config,
> >> > + .owner = 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 = {
> >> > .config = imx_pwm_config_v1,
> >> > .set_enable = imx_pwm_set_enable_v1,
> >> > + .pwm_ops = &imx_pwm_ops_v1,
> >> > };
> >> >
> >> > static struct imx_pwm_data imx_pwm_data_v2 = {
> >> > .config = imx_pwm_config_v2,
> >> > .set_enable = imx_pwm_set_enable_v2,
> >> > + .pwm_ops = &imx_pwm_ops_v2,
> >> > };
> >> >
> >> > static const struct of_device_id imx_pwm_dt_ids[] = {
> >> > @@ -282,6 +321,8 @@ static int imx_pwm_probe(struct
> >> > platform_device *pdev) if (!of_id)
> >> > return -ENODEV;
> >> >
> >> > + data = of_id->data;
> >> > +
> >> > imx = devm_kzalloc(&pdev->dev, sizeof(*imx),
> >> > GFP_KERNEL); if (imx == 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 = &imx_pwm_ops;
> >> > + imx->chip.ops = data->pwm_ops;
> >> > imx->chip.dev = &pdev->dev;
> >> > imx->chip.base = -1;
> >> > imx->chip.npwm = 1;
> >> > imx->chip.can_sleep = true;
> >> > + if (data->pwm_ops->set_polarity) {
> >> > + dev_dbg(&pdev->dev, "PWM supports output
> >> > inversion\n");
> >> > + imx->chip.of_xlate = of_pwm_xlate_with_flags;
> >> > + imx->chip.of_pwm_n_cells = 3;
> >> > + }
> >> >
> >> > r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> >> > imx->mmio_base = devm_ioremap_resource(&pdev->dev, r);
> >> > if (IS_ERR(imx->mmio_base))
> >> > return PTR_ERR(imx->mmio_base);
> >> >
> >> > - data = of_id->data;
> >> > imx->config = data->config;
> >> > imx->set_enable = data->set_enable;
> >>
> >
> > Best regards,
> >
> > Łukasz Majewski
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