Messages in this thread | | | Date | Tue, 13 Jun 2023 13:54:51 -0700 | Subject | Re: [PATCH v3 1/3] dt: psci: Add arm,psci-sys-reset2-vendor-param property | From | Elliot Berman <> |
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Reviving this very old thread. In case folks don't have in their mailbox, here is archive link:
https://lore.kernel.org/all/20200320120105.GA36658@C02TD0UTHF1T.local/
On 3/20/2020 5:01 AM, Mark Rutland wrote: > Hi Elliot, > > On Thu, Mar 05, 2020 at 11:05:27AM -0800, Elliot Berman wrote: >> Some implementors of PSCI may wish to use a different reset type than >> SYSTEM_WARM_RESET. For instance, Qualcomm SoCs support an alternate >> reset_type which may be used in more warm reboot scenarios than >> SYSTEM_WARM_RESET permits (e.g. to reboot into recovery mode). > > To be honest, I'm still confused by this series, and I think that these > patches indicate a larger problem that we cannot solve generally (e.g. > on other platofrms and/or with ACPI). > > I think the underlying issue is whether the semantics for: > > a) Linux's RESET_WARM and RESET_SOFT > b) PSCI's SYSTEM_RESET2 SYSTEM_WARM_RESET > > ... actually align in practice, which this series suggests is not the > case. > > If those don't align, then I think that commit: > > 4302e381a870aafb ("firmware/psci: add support for SYSTEM_RESET2") > > ... is not actually reliable, and not something we can support by > default, and we should rethink the code introduce in that commit. > > If (a) and (b) are supposed to align, and the behaviour on your platform > is an erratum, then I think we should treat it as such rather than > adding a property that is open to abuse. > > Thoughts? > I think it's ok for (a) and (b) to align (that invalidates this series). PSCI SYSTEM_RESET2 supports vendor-specific reset types and the PSCI driver doesn't have any way for these vendor-specific resets to happen.
Would a better way be to export a psci_system_reset2 function? I can implement a reboot-mode driver for PSCI system_reset2 for DT-based platforms.
Thanks, Elliot
> Thanks, > Mark. > >> >> Reviewed-by: Sudeep Holla <sudeep.holla@arm.com> >> Signed-off-by: Elliot Berman <eberman@codeaurora.org> >> --- >> Documentation/devicetree/bindings/arm/psci.yaml | 7 +++++++ >> 1 file changed, 7 insertions(+) >> >> diff --git a/Documentation/devicetree/bindings/arm/psci.yaml b/Documentation/devicetree/bindings/arm/psci.yaml >> index 8ef8542..1a9d2dd 100644 >> --- a/Documentation/devicetree/bindings/arm/psci.yaml >> +++ b/Documentation/devicetree/bindings/arm/psci.yaml >> @@ -102,6 +102,13 @@ properties: >> [1] Kernel documentation - ARM idle states bindings >> Documentation/devicetree/bindings/arm/idle-states.txt >> >> + arm,psci-sys-reset2-vendor-param: >> + $ref: /schemas/types.yaml#/definitions/uint32 >> + description: | >> + Vendor-specific reset type parameter to use for SYSTEM_RESET2 during >> + a warm or soft reboot. If no value is provided, then architectural >> + reset type SYSTEM_WARM_RESET is used. >> + >> "#power-domain-cells": >> description: >> The number of cells in a PM domain specifier as per binding in [3]. >> -- >> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, >> a Linux Foundation Collaborative Project > > From mboxrd@z Thu Jan 1 00:00:00 1970 > Return-Path: <SRS0=iAha=5F=lists.infradead.org=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@kernel.org> > X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on > aws-us-west-2-korg-lkml-1.web.codeaurora.org > X-Spam-Level: > X-Spam-Status: No, score=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, > DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, > SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no > version=3.4.0 > Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) > by smtp.lore.kernel.org (Postfix) with ESMTP id 4F3C9C43333 > for <infradead-linux-arm-kernel@archiver.kernel.org>; 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> Fri, 20 Mar 2020 05:01:07 -0700 (PDT) > Date: Fri, 20 Mar 2020 12:01:05 +0000 > From: Mark Rutland <mark.rutland@arm.com> > To: Elliot Berman <eberman@codeaurora.org> > Subject: Re: [PATCH v3 1/3] dt: psci: Add arm,psci-sys-reset2-vendor-param > property > Message-ID: <20200320120105.GA36658@C02TD0UTHF1T.local> > References: <1583435129-31356-1-git-send-email-eberman@codeaurora.org> > <1583435129-31356-2-git-send-email-eberman@codeaurora.org> > MIME-Version: 1.0 > Content-Disposition: inline > In-Reply-To: <1583435129-31356-2-git-send-email-eberman@codeaurora.org> > X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 > X-CRM114-CacheID: sfid-20200320_050112_965539_E60DC8A3 > X-CRM114-Status: GOOD ( 19.35 ) > X-BeenThere: linux-arm-kernel@lists.infradead.org > X-Mailman-Version: 2.1.29 > Precedence: list > List-Id: <linux-arm-kernel.lists.infradead.org> > List-Unsubscribe: <http://lists.infradead.org/mailman/options/linux-arm-kernel>, > <mailto:linux-arm-kernel-request@lists.infradead.org?subject=unsubscribe> > List-Archive: <http://lists.infradead.org/pipermail/linux-arm-kernel/> > List-Post: <mailto:linux-arm-kernel@lists.infradead.org> > List-Help: <mailto:linux-arm-kernel-request@lists.infradead.org?subject=help> > List-Subscribe: <http://lists.infradead.org/mailman/listinfo/linux-arm-kernel>, > <mailto:linux-arm-kernel-request@lists.infradead.org?subject=subscribe> > Cc: Trilok Soni <tsoni@codeaurora.org>, > Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>, > David Collins <collinsd@codeaurora.org>, linux-arm-msm@vger.kernel.org, > linux-kernel@vger.kernel.org, Bjorn Andersson <bjorn.andersson@linaro.org>, > Sudeep Holla <sudeep.holla@arm.com>, Prasad Sodagudi <psodagud@codeaurora.org>, > linux-arm-kernel@lists.infradead.org > Content-Type: text/plain; charset="us-ascii" > Content-Transfer-Encoding: 7bit > Sender: "linux-arm-kernel" <linux-arm-kernel-bounces@lists.infradead.org> > Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org > > Hi Elliot, > > On Thu, Mar 05, 2020 at 11:05:27AM -0800, Elliot Berman wrote: >> Some implementors of PSCI may wish to use a different reset type than >> SYSTEM_WARM_RESET. For instance, Qualcomm SoCs support an alternate >> reset_type which may be used in more warm reboot scenarios than >> SYSTEM_WARM_RESET permits (e.g. to reboot into recovery mode). > > To be honest, I'm still confused by this series, and I think that these > patches indicate a larger problem that we cannot solve generally (e.g. > on other platofrms and/or with ACPI). > > I think the underlying issue is whether the semantics for: > > a) Linux's RESET_WARM and RESET_SOFT > b) PSCI's SYSTEM_RESET2 SYSTEM_WARM_RESET > > ... actually align in practice, which this series suggests is not the > case. > > If those don't align, then I think that commit: > > 4302e381a870aafb ("firmware/psci: add support for SYSTEM_RESET2") > > ... is not actually reliable, and not something we can support by > default, and we should rethink the code introduce in that commit. > > If (a) and (b) are supposed to align, and the behaviour on your platform > is an erratum, then I think we should treat it as such rather than > adding a property that is open to abuse. > > Thoughts? > > Thanks, > Mark. > >> >> Reviewed-by: Sudeep Holla <sudeep.holla@arm.com> >> Signed-off-by: Elliot Berman <eberman@codeaurora.org> >> --- >> Documentation/devicetree/bindings/arm/psci.yaml | 7 +++++++ >> 1 file changed, 7 insertions(+) >> >> diff --git a/Documentation/devicetree/bindings/arm/psci.yaml b/Documentation/devicetree/bindings/arm/psci.yaml >> index 8ef8542..1a9d2dd 100644 >> --- a/Documentation/devicetree/bindings/arm/psci.yaml >> +++ b/Documentation/devicetree/bindings/arm/psci.yaml >> @@ -102,6 +102,13 @@ properties: >> [1] Kernel documentation - ARM idle states bindings >> Documentation/devicetree/bindings/arm/idle-states.txt >> >> + arm,psci-sys-reset2-vendor-param: >> + $ref: /schemas/types.yaml#/definitions/uint32 >> + description: | >> + Vendor-specific reset type parameter to use for SYSTEM_RESET2 during >> + a warm or soft reboot. If no value is provided, then architectural >> + reset type SYSTEM_WARM_RESET is used. >> + >> "#power-domain-cells": >> description: >> The number of cells in a PM domain specifier as per binding in [3]. >> -- >> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, >> a Linux Foundation Collaborative Project > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel >
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