From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753751AbbIOQHH (ORCPT ); Tue, 15 Sep 2015 12:07:07 -0400 Received: from fw-tnat.cambridge.arm.com ([217.140.96.140]:52620 "EHLO cam-smtp0.cambridge.arm.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752395AbbIOQHD (ORCPT ); Tue, 15 Sep 2015 12:07:03 -0400 From: Punit Agrawal To: "Jon Medhurst \(Tixy\)" Cc: Mark Rutland , "devicetree\@vger.kernel.org" , "linux-pm\@vger.kernel.org" , Liviu Dudau , "linux-kernel\@vger.kernel.org" , "lm-sensors\@lm-sensors.org" , "edubezval\@gmail.com" , "robh+dt\@kernel.org" , "linux\@roeck-us.net" , Sudeep Holla , "linux-arm-kernel\@lists.infradead.org" Subject: Re: [PATCH v3 1/5] Documentation: add DT bindings for ARM SCPI sensors References: <1442235619-4029-1-git-send-email-punit.agrawal@arm.com> <1442235619-4029-2-git-send-email-punit.agrawal@arm.com> <20150914131448.GC7002@leverpostej> <9hhh9mxf7lg.fsf@e105922-lin.cambridge.arm.com> <20150914134949.GE7002@leverpostej> <9hhk2rtdq1f.fsf@e105922-lin.cambridge.arm.com> <1442251092.2850.53.camel@linaro.org> <9hhy4g89g64.fsf@e105922-lin.cambridge.arm.com> <1442313962.2917.25.camel@linaro.org> Date: Tue, 15 Sep 2015 17:04:48 +0100 In-Reply-To: <1442313962.2917.25.camel@linaro.org> (Jon Medhurst's message of "Tue, 15 Sep 2015 11:46:02 +0100") Message-ID: <9hheghzvfbz.fsf@e105922-lin.cambridge.arm.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.5 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org "Jon Medhurst (Tixy)" writes: > On Tue, 2015-09-15 at 10:37 +0100, Punit Agrawal wrote: >> "Jon Medhurst (Tixy)" writes: >> >> > On Mon, 2015-09-14 at 15:38 +0100, Punit Agrawal wrote: >> >> Mark Rutland writes: >> >> > [...] >> >> The way the SCP interface is defined, the sensor identifiers are >> >> contiguous, >> > >> > Is there any documentation other than DUI0922A? [1] From what I can seen >> > that just says it's a 16-bit value and doesn't put any particular >> > constraints on its value. >> >> Although not explicitly stated, if you look at the Get Sensor Capability >> [2] and Get Sensor Info [3] commands you can indirectly infer that the >> Sensor IDs are contiguous. > > I personally wouldn't even indirectly infer they are contiguous from > what the document says. If I were implementing the firmware I would feel > quite in my rights to, for example, use the top 8 bits of the ID for a > sensor type and the bottom 8 for an index, if that made dispatching of > requests more efficient. Or if some optional hardware was detected as > missing, leaving some holes in ID space. True. And without a command to convey the list of valid IDs, the consumer of the API would have to iterate over the entire 16bit space to locate valid IDs. > > As a specification of a 'standard' the document seems to be rather > lacking. So, Sensor ID should be documented as being "an unsigned > integer less than then number of sensors returned by the Get Sensor > Capability command", or something like that. I guess clocks and other > devices suffer from similar lack of specificity. I was thinking of suggesting something similar as an update. > >> Not the strongest guarantee I know. >> >> All platforms currently using SCP (Juno R0 and R1) do indeed expose >> contiguous identifiers. > > IMO, Linux drivers should be coded to the standard or written > specification (where they are available) not the particular > implementations available. > >> > >> > [1] http://community.arm.com/servlet/JiveServlet/download/8401-40-18262/DUI0922A_scp_message_interface.pdf >> [2] http://arminfo.emea.arm.com/help/index.jsp?topic=/com.arm.doc.dui0922b/ch03s02s21.html >> [3] http://arminfo.emea.arm.com/help/index.jsp?topic=/com.arm.doc.dui0922b/BABCCCJJ.html > > I think those links are on ARM's intranet, they return NXDOMAIN for me. Apologies, the below should work. [2] http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.dui0922b/ch03s02s21.html [3] http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.dui0922b/BABCCCJJ.html From mboxrd@z Thu Jan 1 00:00:00 1970 From: Punit Agrawal Subject: Re: [PATCH v3 1/5] Documentation: add DT bindings for ARM SCPI sensors Date: Tue, 15 Sep 2015 17:04:48 +0100 Message-ID: <9hheghzvfbz.fsf@e105922-lin.cambridge.arm.com> References: <1442235619-4029-1-git-send-email-punit.agrawal@arm.com> <1442235619-4029-2-git-send-email-punit.agrawal@arm.com> <20150914131448.GC7002@leverpostej> <9hhh9mxf7lg.fsf@e105922-lin.cambridge.arm.com> <20150914134949.GE7002@leverpostej> <9hhk2rtdq1f.fsf@e105922-lin.cambridge.arm.com> <1442251092.2850.53.camel@linaro.org> <9hhy4g89g64.fsf@e105922-lin.cambridge.arm.com> <1442313962.2917.25.camel@linaro.org> Mime-Version: 1.0 Content-Type: text/plain Return-path: In-Reply-To: <1442313962.2917.25.camel@linaro.org> (Jon Medhurst's message of "Tue, 15 Sep 2015 11:46:02 +0100") Sender: linux-pm-owner@vger.kernel.org To: "Jon Medhurst (Tixy)" Cc: Mark Rutland , "devicetree@vger.kernel.org" , "linux-pm@vger.kernel.org" , Liviu Dudau , "linux-kernel@vger.kernel.org" , "lm-sensors@lm-sensors.org" , "edubezval@gmail.com" , "robh+dt@kernel.org" , "linux@roeck-us.net" , Sudeep Holla , "linux-arm-kernel@lists.infradead.org" List-Id: devicetree@vger.kernel.org "Jon Medhurst (Tixy)" writes: > On Tue, 2015-09-15 at 10:37 +0100, Punit Agrawal wrote: >> "Jon Medhurst (Tixy)" writes: >> >> > On Mon, 2015-09-14 at 15:38 +0100, Punit Agrawal wrote: >> >> Mark Rutland writes: >> >> > [...] >> >> The way the SCP interface is defined, the sensor identifiers are >> >> contiguous, >> > >> > Is there any documentation other than DUI0922A? [1] From what I can seen >> > that just says it's a 16-bit value and doesn't put any particular >> > constraints on its value. >> >> Although not explicitly stated, if you look at the Get Sensor Capability >> [2] and Get Sensor Info [3] commands you can indirectly infer that the >> Sensor IDs are contiguous. > > I personally wouldn't even indirectly infer they are contiguous from > what the document says. If I were implementing the firmware I would feel > quite in my rights to, for example, use the top 8 bits of the ID for a > sensor type and the bottom 8 for an index, if that made dispatching of > requests more efficient. Or if some optional hardware was detected as > missing, leaving some holes in ID space. True. And without a command to convey the list of valid IDs, the consumer of the API would have to iterate over the entire 16bit space to locate valid IDs. > > As a specification of a 'standard' the document seems to be rather > lacking. So, Sensor ID should be documented as being "an unsigned > integer less than then number of sensors returned by the Get Sensor > Capability command", or something like that. I guess clocks and other > devices suffer from similar lack of specificity. I was thinking of suggesting something similar as an update. > >> Not the strongest guarantee I know. >> >> All platforms currently using SCP (Juno R0 and R1) do indeed expose >> contiguous identifiers. > > IMO, Linux drivers should be coded to the standard or written > specification (where they are available) not the particular > implementations available. > >> > >> > [1] http://community.arm.com/servlet/JiveServlet/download/8401-40-18262/DUI0922A_scp_message_interface.pdf >> [2] http://arminfo.emea.arm.com/help/index.jsp?topic=/com.arm.doc.dui0922b/ch03s02s21.html >> [3] http://arminfo.emea.arm.com/help/index.jsp?topic=/com.arm.doc.dui0922b/BABCCCJJ.html > > I think those links are on ARM's intranet, they return NXDOMAIN for me. Apologies, the below should work. [2] http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.dui0922b/ch03s02s21.html [3] http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.dui0922b/BABCCCJJ.html From mboxrd@z Thu Jan 1 00:00:00 1970 From: punit.agrawal@arm.com (Punit Agrawal) Date: Tue, 15 Sep 2015 17:04:48 +0100 Subject: [PATCH v3 1/5] Documentation: add DT bindings for ARM SCPI sensors In-Reply-To: <1442313962.2917.25.camel@linaro.org> (Jon Medhurst's message of "Tue, 15 Sep 2015 11:46:02 +0100") References: <1442235619-4029-1-git-send-email-punit.agrawal@arm.com> <1442235619-4029-2-git-send-email-punit.agrawal@arm.com> <20150914131448.GC7002@leverpostej> <9hhh9mxf7lg.fsf@e105922-lin.cambridge.arm.com> <20150914134949.GE7002@leverpostej> <9hhk2rtdq1f.fsf@e105922-lin.cambridge.arm.com> <1442251092.2850.53.camel@linaro.org> <9hhy4g89g64.fsf@e105922-lin.cambridge.arm.com> <1442313962.2917.25.camel@linaro.org> Message-ID: <9hheghzvfbz.fsf@e105922-lin.cambridge.arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org "Jon Medhurst (Tixy)" writes: > On Tue, 2015-09-15 at 10:37 +0100, Punit Agrawal wrote: >> "Jon Medhurst (Tixy)" writes: >> >> > On Mon, 2015-09-14 at 15:38 +0100, Punit Agrawal wrote: >> >> Mark Rutland writes: >> >> > [...] >> >> The way the SCP interface is defined, the sensor identifiers are >> >> contiguous, >> > >> > Is there any documentation other than DUI0922A? [1] From what I can seen >> > that just says it's a 16-bit value and doesn't put any particular >> > constraints on its value. >> >> Although not explicitly stated, if you look at the Get Sensor Capability >> [2] and Get Sensor Info [3] commands you can indirectly infer that the >> Sensor IDs are contiguous. > > I personally wouldn't even indirectly infer they are contiguous from > what the document says. If I were implementing the firmware I would feel > quite in my rights to, for example, use the top 8 bits of the ID for a > sensor type and the bottom 8 for an index, if that made dispatching of > requests more efficient. Or if some optional hardware was detected as > missing, leaving some holes in ID space. True. And without a command to convey the list of valid IDs, the consumer of the API would have to iterate over the entire 16bit space to locate valid IDs. > > As a specification of a 'standard' the document seems to be rather > lacking. So, Sensor ID should be documented as being "an unsigned > integer less than then number of sensors returned by the Get Sensor > Capability command", or something like that. I guess clocks and other > devices suffer from similar lack of specificity. I was thinking of suggesting something similar as an update. > >> Not the strongest guarantee I know. >> >> All platforms currently using SCP (Juno R0 and R1) do indeed expose >> contiguous identifiers. > > IMO, Linux drivers should be coded to the standard or written > specification (where they are available) not the particular > implementations available. > >> > >> > [1] http://community.arm.com/servlet/JiveServlet/download/8401-40-18262/DUI0922A_scp_message_interface.pdf >> [2] http://arminfo.emea.arm.com/help/index.jsp?topic=/com.arm.doc.dui0922b/ch03s02s21.html >> [3] http://arminfo.emea.arm.com/help/index.jsp?topic=/com.arm.doc.dui0922b/BABCCCJJ.html > > I think those links are on ARM's intranet, they return NXDOMAIN for me. Apologies, the below should work. [2] http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.dui0922b/ch03s02s21.html [3] http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.dui0922b/BABCCCJJ.html