From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joshua Clayton Subject: Re: [PATCH 1/6] binding-doc: power: pwrseq-generic: add binding doc for generic power sequence library Date: Thu, 7 Jul 2016 16:53:07 -0700 Message-ID: <577EEB63.3020007@gmail.com> References: <1467882892-27589-1-git-send-email-peter.chen@nxp.com> <1467882892-27589-2-git-send-email-peter.chen@nxp.com> <1467884834.4236.36.camel@pengutronix.de> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1467884834.4236.36.camel-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Philipp Zabel , Peter Chen Cc: mark.rutland-5wv7dgnIgG8@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, ulf.hansson-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org, stephen.boyd-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org, oscar-Bdbr4918Nnnk1uMJSBkQmQ@public.gmane.org, arnd-r2nGTMty4D4@public.gmane.org, pawel.moll-5wv7dgnIgG8@public.gmane.org, linux-pm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, gregkh-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r@public.gmane.org, k.kozlowski-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org, linux-usb-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, sre-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, mail-APzI5cXaD1zVlRWJc41N0YvC60bnQu0Y@public.gmane.org, broonie-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, stern-nwvwT67g6+6dFdvTe/nMLpVzexx5G7lz@public.gmane.org, festevam-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, troy.kisky-Q5RJGjKts06CY9SHAMCTRUEOCMrvLtNR@public.gmane.org, shawnguo-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, s.hauer-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org List-Id: devicetree@vger.kernel.org On 07/07/2016 02:47 AM, Philipp Zabel wrote: > Am Donnerstag, den 07.07.2016, 17:14 +0800 schrieb Peter Chen: >> Add binding doc for generic power sequence library. >> >> Signed-off-by: Peter Chen >> --- >> .../bindings/power/pwrseq/pwrseq-generic.txt | 56 ++++++++++++++++++++++ >> 1 file changed, 56 insertions(+) >> create mode 100644 Documentation/devicetree/bindings/power/pwrseq/pwrseq-generic.txt >> >> diff --git a/Documentation/devicetree/bindings/power/pwrseq/pwrseq-generic.txt b/Documentation/devicetree/bindings/power/pwrseq/pwrseq-generic.txt >> new file mode 100644 >> index 0000000..4b23834 >> --- /dev/null >> +++ b/Documentation/devicetree/bindings/power/pwrseq/pwrseq-generic.txt >> @@ -0,0 +1,56 @@ >> +The generic power sequence library >> + >> +Some hard-wired USB/MMC devices need to do power sequence to let the >> +device work normally, the typical power sequence like: enable USB >> +PHY clock, toggle reset pin, etc. But current Linux USB driver >> +lacks of such code to do it, it may cause some hard-wired USB devices >> +works abnormal or can't be recognized by controller at all. The >> +power sequence will be done before this device can be found at USB >> +bus. >> + >> +The power sequence properties is under the device node. >> + >> +Required properties: >> +- power-sequence: this device needs to do power sequence before enumeration >> + >> +Optional properties: >> +- clocks: the input clock for device. >> +- clock-name: must be "pwrseq-clk" > The "-clk" in the clock name is redundant. > >> +- pwrseq-reset-gpios: Should specify the GPIO for reset. >> +- pwrseq-reset-duration-us: the duration in microsecond for assert reset signal. > I understand you want to make it explicit that this GPIO is for the > pwrseq library, but are we really gaining anything over just calling > these reset-gpios and reset-duration-us? > The same applies to the clock name above. using reset-gpios makes sense to me too. The above "power-sequence" might then be better called "reset-on-init", But really, if a device has a reset gpio shouldn't the default behavior be to reset it on boot and when coming back from sleep? Is a special property even needed? > >> +Below is the example of USB power sequence properties on USB device >> +nodes which have two level USB hubs. >> + >> +&usbotg1 { >> + vbus-supply = <®_usb_otg1_vbus>; >> + pinctrl-names = "default"; >> + pinctrl-0 = <&pinctrl_usb_otg1_id>; >> + status = "okay"; >> + >> + #address-cells = <1>; >> + #size-cells = <0>; >> + hub: genesys@1 { >> + compatible = "usb5e3,608"; >> + reg = <1>; >> + >> + power-sequence; >> + clocks = <&clks IMX6SX_CLK_CKO>; >> + clock-names = "pwrseq-clk"; >> + pwrseq-reset-gpios = <&gpio4 5 GPIO_ACTIVE_LOW>; /* hub reset pin */ >> + pwrseq-reset-duration-us = <10>; >> + >> + #address-cells = <1>; >> + #size-cells = <0>; >> + ethernet: asix@1 { >> + compatible = "usbb95,1708"; >> + reg = <1>; >> + >> + power-sequence; >> + clocks = <&clks IMX6SX_CLK_IPG>; >> + clock-names = "pwrseq-clk"; >> + pwrseq-reset-gpios = <&gpio4 6 GPIO_ACTIVE_LOW>; /* ethernet_rst */ >> + pwrseq-reset-duration-us = <15>; >> + }; > This looks weird. The hub and ethernet chips don't have "pwrseq" clock > and reset input pins. I'd remove the clock-names and pwrseq- reset > prefix. > > regards > Philipp > > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html