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Fri, 13 Jun 2025 16:23:31 -0700 (PDT) Received: from [10.67.48.245] ([192.19.223.252]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2365deca282sm20135825ad.205.2025.06.13.16.23.29 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 13 Jun 2025 16:23:30 -0700 (PDT) Message-ID: <37f6825e-fba2-49c9-a802-abba1e5343a9@broadcom.com> Date: Fri, 13 Jun 2025 16:23:28 -0700 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 1/2] PCI: brcmstb: Add a way to indicate if PCIe bridge is active To: Jim Quinlan , linux-pci@vger.kernel.org, Nicolas Saenz Julienne , Bjorn Helgaas , Lorenzo Pieralisi , Cyril Brulebois , bcm-kernel-feedback-list@broadcom.com, jim2101024@gmail.com Cc: Florian Fainelli , Lorenzo Pieralisi , =?UTF-8?Q?Krzysztof_Wilczy=C5=84ski?= , Manivannan Sadhasivam , Rob Herring , "moderated list:BROADCOM BCM2711/BCM2835 ARM ARCHITECTURE" , "moderated list:BROADCOM BCM2711/BCM2835 ARM ARCHITECTURE" , open list References: <20250613220843.698227-1-james.quinlan@broadcom.com> <20250613220843.698227-2-james.quinlan@broadcom.com> Content-Language: en-US From: Florian Fainelli Autocrypt: addr=florian.fainelli@broadcom.com; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250613_162332_638484_5370A5EA X-CRM114-Status: GOOD ( 14.50 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 6/13/25 15:08, Jim Quinlan wrote: > In a future commit, a new handler will be introduced that in part does > reads and writes to some of the PCIe registers. When this handler is > invoked, it is paramount that it does not do these register accesses when > the PCIe bridge is inactive, as this will cause CPU abort errors. > > To solve this we keep a spinlock that guards a variable which indicates > whether the bridge is on or off. When the bridge is on, access of the PCIe > HW registers may proceed. > > Since there are multiple ways to reset the bridge, we introduce a general > function to obtain the spinlock, call the specific function that is used > for the specific SoC, sets the bridge active indicator variable, and > releases the spinlock. > > Signed-off-by: Jim Quinlan Reviewed-by: Florian Fainelli -- Florian