From mboxrd@z Thu Jan 1 00:00:00 1970 From: "A.S. Dong" Subject: RE: [PATCH 2/2] pinctrl: pinctrl-imx: do not assume mux 0 is gpio Date: Thu, 18 May 2017 07:00:00 +0000 Message-ID: References: <1494830906-6442-1-git-send-email-aisheng.dong@nxp.com> <1494830906-6442-3-git-send-email-aisheng.dong@nxp.com> <6d47abc0527ae6f2214a9b37dfbeb154@agner.ch> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Content-Language: en-US List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=m.gmane.org@lists.infradead.org To: Stefan Agner Cc: Alexandre Courbot , Andy Duan , Jacky Bai , "linus.walleij@linaro.org" , "linux-gpio@vger.kernel.org" , "kernel@pengutronix.de" , "shawnguo@kernel.org" , "linux-arm-kernel@lists.infradead.org" List-Id: linux-gpio@vger.kernel.org > -----Original Message----- > From: Stefan Agner [mailto:stefan@agner.ch] > Sent: Thursday, May 18, 2017 2:16 AM > To: A.S. Dong > Cc: linux-gpio@vger.kernel.org; linux-arm-kernel@lists.infradead.org; > linus.walleij@linaro.org; shawnguo@kernel.org; Jacky Bai; Andy Duan; > kernel@pengutronix.de; Alexandre Courbot > Subject: Re: [PATCH 2/2] pinctrl: pinctrl-imx: do not assume mux 0 is gpio > > On 2017-05-17 00:18, A.S. Dong wrote: > >> -----Original Message----- > >> From: Stefan Agner [mailto:stefan@agner.ch] > >> Sent: Tuesday, May 16, 2017 1:27 AM > >> To: A.S. Dong > >> Cc: linux-gpio@vger.kernel.org; linux-arm-kernel@lists.infradead.org; > >> linus.walleij@linaro.org; shawnguo@kernel.org; Jacky Bai; Andy Duan; > >> kernel@pengutronix.de; Alexandre Courbot > >> Subject: Re: [PATCH 2/2] pinctrl: pinctrl-imx: do not assume mux 0 is > >> gpio > >> > >> On 2017-05-14 23:48, Dong Aisheng wrote: > >> > Do not assume MUX 0 is GPIO function in core driver as a different > >> > SoC may have different value. e.g. MX7ULP Mux 1 is GPIO. > >> > > >> > Cc: Linus Walleij > >> > Cc: Alexandre Courbot > >> > Cc: Shawn Guo > >> > Cc: Stefan Agner > >> > Cc: Fugang Duan > >> > Cc: Bai Ping > >> > Signed-off-by: Dong Aisheng > >> > --- > >> > drivers/pinctrl/freescale/pinctrl-imx.c | 3 ++- > >> > 1 file changed, 2 insertions(+), 1 deletion(-) > >> > > >> > diff --git a/drivers/pinctrl/freescale/pinctrl-imx.c > >> > b/drivers/pinctrl/freescale/pinctrl-imx.c > >> > index 0d6aaca..ed8ea32 100644 > >> > --- a/drivers/pinctrl/freescale/pinctrl-imx.c > >> > +++ b/drivers/pinctrl/freescale/pinctrl-imx.c > >> > @@ -281,7 +281,7 @@ static int imx_pmx_gpio_request_enable(struct > >> > pinctrl_dev *pctldev, > >> > continue; > >> > for (pin = 0; pin < grp->num_pins; pin++) { > >> > imx_pin = &((struct imx_pin *)(grp->data))[pin]; > >> > - if (imx_pin->pin == offset && !imx_pin->mux_mode) > >> > + if (imx_pin->pin == offset) > >> > goto mux_pin; > >> > >> The reason I added that check was to make sure we pick a mux option > >> which is GPIO... With this change, any pinmux might be picked... > >> > > > > First of all, this seems to be wrong to me that GPIO mux mode is SoC > > Dependant and should not be put in pinctrl-imx core driver. > > Hm, agree, we should consider to move > imx_pmx_gpio_request_enable/disable_free and imx_pmx_gpio_set_direction > into pinctrl-vf610.c > IMX7ULP may want to use imx_pmx_gpio_set_direction as well to support dynamically change GPIO from output to input. > > > > Secondly, I think we may be over worried and it's not quite necessary > > As we did not do the sanity check for both raw config and mux data > > read From Device tree, why only do it for GPIO? > > > > We may trust the data in device tree. > > In Vybrid, there is no need to explicitly assign a pinmux to use a pin as > GPIO. So the pinmux could be anything... The implemented semantics for > Vyrbid is really different than i.MX, see below. > Strange, I do see Vybrid assigning pinmux to GPIO in device tree. e.g. arch/arm/boot/dts/vf-colibri.dtsi pinctrl_esdhc1: esdhc1grp { fsl,pins = < VF610_PAD_PTA24__ESDHC1_CLK 0x31ef VF610_PAD_PTA25__ESDHC1_CMD 0x31ef VF610_PAD_PTA26__ESDHC1_DAT0 0x31ef VF610_PAD_PTA27__ESDHC1_DAT1 0x31ef VF610_PAD_PTA28__ESDHC1_DATA2 0x31ef VF610_PAD_PTA29__ESDHC1_DAT3 0x31ef VF610_PAD_PTB20__GPIO_42 0x219d >; }; > > > >> > } > >> > } > >> > @@ -292,6 +292,7 @@ static int imx_pmx_gpio_request_enable(struct > >> > pinctrl_dev *pctldev, > >> > reg = readl(ipctl->base + pin_reg->mux_reg); > >> > reg &= ~info->mux_mask; > >> > reg |= imx_pin->config; > >> > + reg |= imx_pin->mux_mode << info->mux_shift; > >> > >> ... and muxed... > >> > >> Not sure if we want that. > >> > >> I had to control GPIO output/input through pinctrl since Vybrid does > >> not allow to control that from the GPIO block. > >> > >> However, according to your GPIO patchset, the i.MX 7ULP has a new > >> register GPIO_PDDR to control output from the GPIO block. Is > >> controlling the output driver from IOMUXC still required? > > > > Yes, it's still required. > > > > That sounds weird, what is the GPIO_PDDR for then? Sure I need to enable > the output driver to drive the pin, but can I disable output just using > GPIO_PDDR? No, to fully disable a output, you must disable OBE as well. > > Maybe we have a miss understanding here: > > Lets assume we want to switch a GPIO between output and input: > > echo "output" > /sys/class/gpio/gpioN/direction .. > echo "input" > /sys/class/gpio/gpioN/direction > > Do I need to disable the output driver in the IOMUXC or can we just > disable GPIO_PDDR and use the pin as input? > OBE should also be disabled. Otherwise the input may not function well. > If we can disable the output driver just using GPIO_PDDR, we can avoid the > gpio_set_direction cross call. > > > >> If not, I really would just not use all that "find pinctrl config" > >> hackery... e.g. add a new flag, USE_IOMUXC_FOR_GPIO_OUTPUT, and set > >> that only for Vybrid. > >> > >> This would also align much better with the other i.MX devices, where > >> pinmuxing and GPIO is completely orthogonal. > >> > > > > Actually this patch came only because to make the exist code not break > > MX7ULP. > > > > Actually I'm wondering why we need implement > > imx_pmx_gpio_request_enable function? > > > > Per my understanding, IMX binding already set GPIO mux by Parsing MUX > > mode from device tree, so why need gpio_request_enable which looks > > like is duplicated. > > > > Can you help explain it? > > I suggest to read this clarification email wrt to pinctrl/gpio from Linus > Walleij: > https://lkml.org/lkml/2016/10/10/87 > > To summarize: We have different semantics in Vybrid: The GPIO subsystem > automatically mux the GPIO for you. So in Vybrid, you do not have to mux a > GPIO (but a valid entry in your device tree is needed, but does not > assigned to any node). Okay, Clearer now. But I do see the users of GPIO pads in Vybrid dts. Above is an example which make me confuse at first. > > Is what the driver is doing for Vybrid wrong? It is different from i.MX, > but afaik, it is not really wrong... Its a valid implementation according > to the currently defined semantics... Due to the *need* to touch pinctrl > for direction, I had to implement cross calls anyway, so I thought I might > as well go full mile and also mux the GPIO on request... > It's not strickly wrong. Just a bit confuse that gpio_request_enable seems not quite necessary As we actually already and must define GPIO mux in device tree according To standard IMX binding format. e.g. VF610_PAD_PTB20__GPIO_42 in above sd pad group. That means pinctrl already does the GPIO mux when enable sd function. > So the question is, what semantic do we want for i.MX 7ULP? Since it is a > i.MX device, we probably want the same semantics as i.MX 6/7 is already > using for the sake of consistency. So in this case the > gpio_request_enable/disable callbacks are not needed... > > This is how I hope we can do the implementation for i.MX 7ULP: > - Do not use gpio_request_enable/disable Yes, we do want that. > - Do not use gpio_set_direction either Not, ULP needs it to support GPIO direction switch. > - Users using a GPIO should enable output driver in IOMUXC (just use a pin > configuration where output driver is enabled) Users still need configure OBE/IBE in devicetree for statically assignment. > - The GPIO driver only enables/disables the output driver using its > GPIO_PDDR register depending on GPIO direction No, same reason as the second question. So, finnaly, I think the solution may be: 1. If Vybrid does not use gpio_request_enable/disable, we can simply remove it. Both driver keeps using pinctrl gpio_set_direction. Or. 2. Make gpio_request_enable/disable and gpio_set_direction As pinctrl-imx core driver callbacks. And only assign gpio_set_direction For IMX7ULP platform driver while assign both for Vybrid. Which one would you prefer? Regards Dong Aisheng From mboxrd@z Thu Jan 1 00:00:00 1970 From: aisheng.dong@nxp.com (A.S. Dong) Date: Thu, 18 May 2017 07:00:00 +0000 Subject: [PATCH 2/2] pinctrl: pinctrl-imx: do not assume mux 0 is gpio In-Reply-To: References: <1494830906-6442-1-git-send-email-aisheng.dong@nxp.com> <1494830906-6442-3-git-send-email-aisheng.dong@nxp.com> <6d47abc0527ae6f2214a9b37dfbeb154@agner.ch> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org > -----Original Message----- > From: Stefan Agner [mailto:stefan at agner.ch] > Sent: Thursday, May 18, 2017 2:16 AM > To: A.S. Dong > Cc: linux-gpio at vger.kernel.org; linux-arm-kernel at lists.infradead.org; > linus.walleij at linaro.org; shawnguo at kernel.org; Jacky Bai; Andy Duan; > kernel at pengutronix.de; Alexandre Courbot > Subject: Re: [PATCH 2/2] pinctrl: pinctrl-imx: do not assume mux 0 is gpio > > On 2017-05-17 00:18, A.S. Dong wrote: > >> -----Original Message----- > >> From: Stefan Agner [mailto:stefan at agner.ch] > >> Sent: Tuesday, May 16, 2017 1:27 AM > >> To: A.S. Dong > >> Cc: linux-gpio at vger.kernel.org; linux-arm-kernel at lists.infradead.org; > >> linus.walleij at linaro.org; shawnguo at kernel.org; Jacky Bai; Andy Duan; > >> kernel at pengutronix.de; Alexandre Courbot > >> Subject: Re: [PATCH 2/2] pinctrl: pinctrl-imx: do not assume mux 0 is > >> gpio > >> > >> On 2017-05-14 23:48, Dong Aisheng wrote: > >> > Do not assume MUX 0 is GPIO function in core driver as a different > >> > SoC may have different value. e.g. MX7ULP Mux 1 is GPIO. > >> > > >> > Cc: Linus Walleij > >> > Cc: Alexandre Courbot > >> > Cc: Shawn Guo > >> > Cc: Stefan Agner > >> > Cc: Fugang Duan > >> > Cc: Bai Ping > >> > Signed-off-by: Dong Aisheng > >> > --- > >> > drivers/pinctrl/freescale/pinctrl-imx.c | 3 ++- > >> > 1 file changed, 2 insertions(+), 1 deletion(-) > >> > > >> > diff --git a/drivers/pinctrl/freescale/pinctrl-imx.c > >> > b/drivers/pinctrl/freescale/pinctrl-imx.c > >> > index 0d6aaca..ed8ea32 100644 > >> > --- a/drivers/pinctrl/freescale/pinctrl-imx.c > >> > +++ b/drivers/pinctrl/freescale/pinctrl-imx.c > >> > @@ -281,7 +281,7 @@ static int imx_pmx_gpio_request_enable(struct > >> > pinctrl_dev *pctldev, > >> > continue; > >> > for (pin = 0; pin < grp->num_pins; pin++) { > >> > imx_pin = &((struct imx_pin *)(grp->data))[pin]; > >> > - if (imx_pin->pin == offset && !imx_pin->mux_mode) > >> > + if (imx_pin->pin == offset) > >> > goto mux_pin; > >> > >> The reason I added that check was to make sure we pick a mux option > >> which is GPIO... With this change, any pinmux might be picked... > >> > > > > First of all, this seems to be wrong to me that GPIO mux mode is SoC > > Dependant and should not be put in pinctrl-imx core driver. > > Hm, agree, we should consider to move > imx_pmx_gpio_request_enable/disable_free and imx_pmx_gpio_set_direction > into pinctrl-vf610.c > IMX7ULP may want to use imx_pmx_gpio_set_direction as well to support dynamically change GPIO from output to input. > > > > Secondly, I think we may be over worried and it's not quite necessary > > As we did not do the sanity check for both raw config and mux data > > read From Device tree, why only do it for GPIO? > > > > We may trust the data in device tree. > > In Vybrid, there is no need to explicitly assign a pinmux to use a pin as > GPIO. So the pinmux could be anything... The implemented semantics for > Vyrbid is really different than i.MX, see below. > Strange, I do see Vybrid assigning pinmux to GPIO in device tree. e.g. arch/arm/boot/dts/vf-colibri.dtsi pinctrl_esdhc1: esdhc1grp { fsl,pins = < VF610_PAD_PTA24__ESDHC1_CLK 0x31ef VF610_PAD_PTA25__ESDHC1_CMD 0x31ef VF610_PAD_PTA26__ESDHC1_DAT0 0x31ef VF610_PAD_PTA27__ESDHC1_DAT1 0x31ef VF610_PAD_PTA28__ESDHC1_DATA2 0x31ef VF610_PAD_PTA29__ESDHC1_DAT3 0x31ef VF610_PAD_PTB20__GPIO_42 0x219d >; }; > > > >> > } > >> > } > >> > @@ -292,6 +292,7 @@ static int imx_pmx_gpio_request_enable(struct > >> > pinctrl_dev *pctldev, > >> > reg = readl(ipctl->base + pin_reg->mux_reg); > >> > reg &= ~info->mux_mask; > >> > reg |= imx_pin->config; > >> > + reg |= imx_pin->mux_mode << info->mux_shift; > >> > >> ... and muxed... > >> > >> Not sure if we want that. > >> > >> I had to control GPIO output/input through pinctrl since Vybrid does > >> not allow to control that from the GPIO block. > >> > >> However, according to your GPIO patchset, the i.MX 7ULP has a new > >> register GPIO_PDDR to control output from the GPIO block. Is > >> controlling the output driver from IOMUXC still required? > > > > Yes, it's still required. > > > > That sounds weird, what is the GPIO_PDDR for then? Sure I need to enable > the output driver to drive the pin, but can I disable output just using > GPIO_PDDR? No, to fully disable a output, you must disable OBE as well. > > Maybe we have a miss understanding here: > > Lets assume we want to switch a GPIO between output and input: > > echo "output" > /sys/class/gpio/gpioN/direction .. > echo "input" > /sys/class/gpio/gpioN/direction > > Do I need to disable the output driver in the IOMUXC or can we just > disable GPIO_PDDR and use the pin as input? > OBE should also be disabled. Otherwise the input may not function well. > If we can disable the output driver just using GPIO_PDDR, we can avoid the > gpio_set_direction cross call. > > > >> If not, I really would just not use all that "find pinctrl config" > >> hackery... e.g. add a new flag, USE_IOMUXC_FOR_GPIO_OUTPUT, and set > >> that only for Vybrid. > >> > >> This would also align much better with the other i.MX devices, where > >> pinmuxing and GPIO is completely orthogonal. > >> > > > > Actually this patch came only because to make the exist code not break > > MX7ULP. > > > > Actually I'm wondering why we need implement > > imx_pmx_gpio_request_enable function? > > > > Per my understanding, IMX binding already set GPIO mux by Parsing MUX > > mode from device tree, so why need gpio_request_enable which looks > > like is duplicated. > > > > Can you help explain it? > > I suggest to read this clarification email wrt to pinctrl/gpio from Linus > Walleij: > https://lkml.org/lkml/2016/10/10/87 > > To summarize: We have different semantics in Vybrid: The GPIO subsystem > automatically mux the GPIO for you. So in Vybrid, you do not have to mux a > GPIO (but a valid entry in your device tree is needed, but does not > assigned to any node). Okay, Clearer now. But I do see the users of GPIO pads in Vybrid dts. Above is an example which make me confuse at first. > > Is what the driver is doing for Vybrid wrong? It is different from i.MX, > but afaik, it is not really wrong... Its a valid implementation according > to the currently defined semantics... Due to the *need* to touch pinctrl > for direction, I had to implement cross calls anyway, so I thought I might > as well go full mile and also mux the GPIO on request... > It's not strickly wrong. Just a bit confuse that gpio_request_enable seems not quite necessary As we actually already and must define GPIO mux in device tree according To standard IMX binding format. e.g. VF610_PAD_PTB20__GPIO_42 in above sd pad group. That means pinctrl already does the GPIO mux when enable sd function. > So the question is, what semantic do we want for i.MX 7ULP? Since it is a > i.MX device, we probably want the same semantics as i.MX 6/7 is already > using for the sake of consistency. So in this case the > gpio_request_enable/disable callbacks are not needed... > > This is how I hope we can do the implementation for i.MX 7ULP: > - Do not use gpio_request_enable/disable Yes, we do want that. > - Do not use gpio_set_direction either Not, ULP needs it to support GPIO direction switch. > - Users using a GPIO should enable output driver in IOMUXC (just use a pin > configuration where output driver is enabled) Users still need configure OBE/IBE in devicetree for statically assignment. > - The GPIO driver only enables/disables the output driver using its > GPIO_PDDR register depending on GPIO direction No, same reason as the second question. So, finnaly, I think the solution may be: 1. If Vybrid does not use gpio_request_enable/disable, we can simply remove it. Both driver keeps using pinctrl gpio_set_direction. Or. 2. Make gpio_request_enable/disable and gpio_set_direction As pinctrl-imx core driver callbacks. And only assign gpio_set_direction For IMX7ULP platform driver while assign both for Vybrid. Which one would you prefer? Regards Dong Aisheng