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([2a02:810d:15c0:828:8fa0:9989:3f72:b14f]) by smtp.gmail.com with ESMTPSA id h2-20020a50c382000000b004ad601533a3sm6626809edf.55.2023.04.12.01.09.06 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 12 Apr 2023 01:09:07 -0700 (PDT) Message-ID: <5a28e520-63e4-dbcf-5b3e-e5097f02dea2@linaro.org> Date: Wed, 12 Apr 2023 10:09:05 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.9.1 Subject: Re: [PATCH v2 1/3] dt-bindings: PCI: brcmstb: Add two optional props Content-Language: en-US To: Jim Quinlan , linux-pci@vger.kernel.org, Nicolas Saenz Julienne , Bjorn Helgaas , Lorenzo Pieralisi , Cyril Brulebois , Phil Elwell , bcm-kernel-feedback-list@broadcom.com, james.quinlan@broadcom.com Cc: Florian Fainelli , Lorenzo Pieralisi , =?UTF-8?Q?Krzysztof_Wilczy=c5=84ski?= , Rob Herring , Krzysztof Kozlowski , "moderated list:BROADCOM BCM7XXX ARM ARCHITECTURE" , "moderated list:BROADCOM BCM2711/BCM2835 ARM ARCHITECTURE" , "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" , open list References: <20230411165919.23955-1-jim2101024@gmail.com> <20230411165919.23955-2-jim2101024@gmail.com> From: Krzysztof Kozlowski In-Reply-To: <20230411165919.23955-2-jim2101024@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On 11/04/2023 18:59, Jim Quinlan wrote: > Regarding "brcm,enable-l1ss": > > The Broadcom STB/CM PCIe HW -- a core that is also used by RPi SOCs -- > requires the driver probe() to deliberately place the HW one of three > CLKREQ# modes: > > (a) CLKREQ# driven by the RC unconditionally > (b) CLKREQ# driven by the EP for ASPM L0s, L1 > (c) Bidirectional CLKREQ#, as used for L1 Substates (L1SS). > > The HW+driver can tell the difference between downstream devices that > need (a) and (b), but does not know when to configure (c). Further, the > HW may cause a CPU abort on boot if guesses wrong regarding the need for > (c). So we introduce the boolean "brcm,enable-l1ss" property to indicate > that (c) is desired. Setting this property only makes sense when the > downstream device is L1SS-capable and the OS is configured to activate > this mode (e.g. policy==superpowersave). > > This property is already present in the Raspian version of Linux, but the > upstream driver implementaion that will follow adds more details and typo, implementation > discerns between (a) and (b). > > Regarding "brcm,completion-timeout-us" > > Our HW will cause a CPU abort if the L1SS exit time is longer than the > PCIe transaction completion abort timeout. We've been asked to make this > configurable, so we are introducing "brcm,completion-timeout-us". > > Signed-off-by: Jim Quinlan What happened here? Where is the changelog? Best regards, Krzysztof