From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752567AbdCEMNm (ORCPT ); Sun, 5 Mar 2017 07:13:42 -0500 Received: from saturn.retrosnub.co.uk ([178.18.118.26]:59992 "EHLO saturn.retrosnub.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752523AbdCEMNj (ORCPT ); Sun, 5 Mar 2017 07:13:39 -0500 Subject: Re: [PATCH v3 1/6] dt-bindings: iio: introduce trigger providers, consumers To: Rob Herring , Fabrice Gasnier References: <1488300679-3259-1-git-send-email-fabrice.gasnier@st.com> <1488300679-3259-2-git-send-email-fabrice.gasnier@st.com> <20170303062126.5bewa5u6o7wu7sy4@rob-hp-laptop> <948e5b96-7a8f-406d-6d03-d129d1b2ce54@kernel.org> Cc: linux@armlinux.org.uk, linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-iio@vger.kernel.org, mark.rutland@arm.com, mcoquelin.stm32@gmail.com, alexandre.torgue@st.com, lars@metafoo.de, knaack.h@gmx.de, pmeerw@pmeerw.net, benjamin.gaignard@linaro.org, benjamin.gaignard@st.com, linus.walleij@linaro.org From: Jonathan Cameron Message-ID: <12a6a2f8-9ff6-a4f0-c9a2-c7de037019ef@kernel.org> Date: Sun, 5 Mar 2017 12:13:36 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.7.0 MIME-Version: 1.0 In-Reply-To: <948e5b96-7a8f-406d-6d03-d129d1b2ce54@kernel.org> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/03/17 11:43, Jonathan Cameron wrote: > On 03/03/17 06:21, Rob Herring wrote: >> On Tue, Feb 28, 2017 at 05:51:14PM +0100, Fabrice Gasnier wrote: >>> Document iio provider and consumer bindings. >>> >>> Signed-off-by: Fabrice Gasnier >>> --- >>> .../devicetree/bindings/iio/iio-bindings.txt | 38 ++++++++++++++++++++++ >>> 1 file changed, 38 insertions(+) >>> >>> diff --git a/Documentation/devicetree/bindings/iio/iio-bindings.txt b/Documentation/devicetree/bindings/iio/iio-bindings.txt >>> index 68d6f8c..01765e9 100644 >>> --- a/Documentation/devicetree/bindings/iio/iio-bindings.txt >>> +++ b/Documentation/devicetree/bindings/iio/iio-bindings.txt >>> @@ -95,3 +95,41 @@ vdd channel is connected to output 0 of the &ref device. >>> io-channels = <&adc 10>, <&adc 11>; >>> io-channel-names = "adc1", "adc2"; >>> }; >>> + >>> +==IIO trigger providers== >>> +Sources of IIO triggers can be represented by any node in the device >>> +tree. Those nodes are designated as IIO trigger providers. IIO trigger >>> +consumer uses a phandle and an IIO trigger specifier to connect to an >>> +IIO trigger provider. >>> +An IIO trigger specifier is an array of one or more cells identifying >>> +the IIO trigger output on a device. The length of an IIO trigger >>> +specifier is defined by the value of a #io-trigger-cells property in >>> +the IIO trigger provider node. >>> + >>> +Required properties: >>> +#io-trigger-cells: >>> + Number of cells in an IIO trigger specifier; Typically >>> + 0 for nodes with a simple IIO trigger output. >>> + >>> +Example: >>> + trig0: interrupt-trigger0 { >>> + #io-trigger-cells = <0>; >>> + compatible = "interrupt-trigger"; >>> + interrupts = <11 0>; >>> + interrupt-parent = <&gpioa>; >>> + } >>> + >>> +==IIO trigger consumers== >>> +Required properties: >>> +- io-triggers: List of phandle representing the IIO trigger specifier. >>> + >>> +Optional properties: >>> +- io-trigger-names : >>> + List of IIO trigger name strings that matches elements >>> + in 'io-triggers' list property. >>> + >>> +Example: >>> + some_trigger_consumer { >>> + io-triggers = <&trig0>; >>> + io-trigger-names = "mytrig"; >>> + } >> >> I have some reservations about this. We could just as easily add the >> interrupt directly to the consumer node and use "trigger" for a standard >> interrupt name. So the question is whether this extra level of >> indirection is needed? > > First thing to note here, is that Fabrice's use of the generic interrupt > trigger is an extremely 'unusual' one! Normal use case is that we have > a random gpio pin providing interrupts to driver triggering on random > devices - there need be no association between the two whatsoever. > So what we are doing here is 'allowing' an interrupt to provide a trigger. > It's not necessarily the one going to be used by any particular device > driver. The decision of which trigger to use is definitely one for > userspace, not something that should be configured in to the device tree. > > For this particular case you could in theory just do it by using an interrupt > as you describe. Ultimately though we should be able to play more complex > games with this device and having it able to handle any trigger - which > includes those not using the direct hardware route. It'll be up to the > driver to figure out when it can use the fast method and when it can't. > > Conversely, even when we are using this hardware route to drive the > triggering it should be possible to hang off a device to be triggered > by the interrupt via the kernel rather than directly. > > So from a device tree point of view we are just describing the fact that > there is a pin, which may be used to trigger something. What that something > is, is a question for userspace not the device tree. > Ah, I'm half asleep this morning. Clearly there is a more general follow up question. If we are arguing these are generic, why are we setting up the mapping in device tree? My gut feeling is we shouldn't be. So I think we need the first chunk above but the latter part should be a job for userspace not the devicetree. Jonathan > Jonathan >> >> Rob >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-iio" in >> the body of a message to majordomo@vger.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html >> > > -- > To unsubscribe from this list: send the line "unsubscribe linux-iio" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > From mboxrd@z Thu Jan 1 00:00:00 1970 From: jic23@kernel.org (Jonathan Cameron) Date: Sun, 5 Mar 2017 12:13:36 +0000 Subject: [PATCH v3 1/6] dt-bindings: iio: introduce trigger providers, consumers In-Reply-To: <948e5b96-7a8f-406d-6d03-d129d1b2ce54@kernel.org> References: <1488300679-3259-1-git-send-email-fabrice.gasnier@st.com> <1488300679-3259-2-git-send-email-fabrice.gasnier@st.com> <20170303062126.5bewa5u6o7wu7sy4@rob-hp-laptop> <948e5b96-7a8f-406d-6d03-d129d1b2ce54@kernel.org> Message-ID: <12a6a2f8-9ff6-a4f0-c9a2-c7de037019ef@kernel.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 05/03/17 11:43, Jonathan Cameron wrote: > On 03/03/17 06:21, Rob Herring wrote: >> On Tue, Feb 28, 2017 at 05:51:14PM +0100, Fabrice Gasnier wrote: >>> Document iio provider and consumer bindings. >>> >>> Signed-off-by: Fabrice Gasnier >>> --- >>> .../devicetree/bindings/iio/iio-bindings.txt | 38 ++++++++++++++++++++++ >>> 1 file changed, 38 insertions(+) >>> >>> diff --git a/Documentation/devicetree/bindings/iio/iio-bindings.txt b/Documentation/devicetree/bindings/iio/iio-bindings.txt >>> index 68d6f8c..01765e9 100644 >>> --- a/Documentation/devicetree/bindings/iio/iio-bindings.txt >>> +++ b/Documentation/devicetree/bindings/iio/iio-bindings.txt >>> @@ -95,3 +95,41 @@ vdd channel is connected to output 0 of the &ref device. >>> io-channels = <&adc 10>, <&adc 11>; >>> io-channel-names = "adc1", "adc2"; >>> }; >>> + >>> +==IIO trigger providers== >>> +Sources of IIO triggers can be represented by any node in the device >>> +tree. Those nodes are designated as IIO trigger providers. IIO trigger >>> +consumer uses a phandle and an IIO trigger specifier to connect to an >>> +IIO trigger provider. >>> +An IIO trigger specifier is an array of one or more cells identifying >>> +the IIO trigger output on a device. The length of an IIO trigger >>> +specifier is defined by the value of a #io-trigger-cells property in >>> +the IIO trigger provider node. >>> + >>> +Required properties: >>> +#io-trigger-cells: >>> + Number of cells in an IIO trigger specifier; Typically >>> + 0 for nodes with a simple IIO trigger output. >>> + >>> +Example: >>> + trig0: interrupt-trigger0 { >>> + #io-trigger-cells = <0>; >>> + compatible = "interrupt-trigger"; >>> + interrupts = <11 0>; >>> + interrupt-parent = <&gpioa>; >>> + } >>> + >>> +==IIO trigger consumers== >>> +Required properties: >>> +- io-triggers: List of phandle representing the IIO trigger specifier. >>> + >>> +Optional properties: >>> +- io-trigger-names : >>> + List of IIO trigger name strings that matches elements >>> + in 'io-triggers' list property. >>> + >>> +Example: >>> + some_trigger_consumer { >>> + io-triggers = <&trig0>; >>> + io-trigger-names = "mytrig"; >>> + } >> >> I have some reservations about this. We could just as easily add the >> interrupt directly to the consumer node and use "trigger" for a standard >> interrupt name. So the question is whether this extra level of >> indirection is needed? > > First thing to note here, is that Fabrice's use of the generic interrupt > trigger is an extremely 'unusual' one! Normal use case is that we have > a random gpio pin providing interrupts to driver triggering on random > devices - there need be no association between the two whatsoever. > So what we are doing here is 'allowing' an interrupt to provide a trigger. > It's not necessarily the one going to be used by any particular device > driver. The decision of which trigger to use is definitely one for > userspace, not something that should be configured in to the device tree. > > For this particular case you could in theory just do it by using an interrupt > as you describe. Ultimately though we should be able to play more complex > games with this device and having it able to handle any trigger - which > includes those not using the direct hardware route. It'll be up to the > driver to figure out when it can use the fast method and when it can't. > > Conversely, even when we are using this hardware route to drive the > triggering it should be possible to hang off a device to be triggered > by the interrupt via the kernel rather than directly. > > So from a device tree point of view we are just describing the fact that > there is a pin, which may be used to trigger something. What that something > is, is a question for userspace not the device tree. > Ah, I'm half asleep this morning. Clearly there is a more general follow up question. If we are arguing these are generic, why are we setting up the mapping in device tree? My gut feeling is we shouldn't be. So I think we need the first chunk above but the latter part should be a job for userspace not the devicetree. Jonathan > Jonathan >> >> Rob >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-iio" in >> the body of a message to majordomo at vger.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html >> > > -- > To unsubscribe from this list: send the line "unsubscribe linux-iio" in > the body of a message to majordomo at vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >