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 > >> > > >> > 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 > >> > 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 = <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