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Message-ID: <5a28e520-63e4-dbcf-5b3e-e5097f02dea2@linaro.org>
Date:   Wed, 12 Apr 2023 10:09:05 +0200
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Subject: Re: [PATCH v2 1/3] dt-bindings: PCI: brcmstb: Add two optional props
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To:     Jim Quinlan <jim2101024@gmail.com>, linux-pci@vger.kernel.org,
        Nicolas Saenz Julienne <nsaenz@kernel.org>,
        Bjorn Helgaas <bhelgaas@google.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
        Cyril Brulebois <kibi@debian.org>,
        Phil Elwell <phil@raspberrypi.com>,
        bcm-kernel-feedback-list@broadcom.com, james.quinlan@broadcom.com
Cc:     Florian Fainelli <f.fainelli@gmail.com>,
        Lorenzo Pieralisi <lpieralisi@kernel.org>,
        =?UTF-8?Q?Krzysztof_Wilczy=c5=84ski?= <kw@linux.com>,
        Rob Herring <robh@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        "moderated list:BROADCOM BCM7XXX ARM ARCHITECTURE" 
        <linux-arm-kernel@lists.infradead.org>,
        "moderated list:BROADCOM BCM2711/BCM2835 ARM ARCHITECTURE" 
        <linux-rpi-kernel@lists.infradead.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@vger.kernel.org>,
        open list <linux-kernel@vger.kernel.org>
References: <20230411165919.23955-1-jim2101024@gmail.com>
 <20230411165919.23955-2-jim2101024@gmail.com>
From:   Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
In-Reply-To: <20230411165919.23955-2-jim2101024@gmail.com>
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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 <jim2101024@gmail.com>

What happened here? Where is the changelog?

Best regards,
Krzysztof