linux-kernel - Re: [PATCH 1/2] PCI: brcmstb: Add a way to indicate if PCIe bridge is active

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Message-ID: <37f6825e-fba2-49c9-a802-abba1e5343a9@broadcom.com>
Date: Fri, 13 Jun 2025 16:23:28 -0700
From: Florian Fainelli <florian.fainelli@...adcom.com>
To: Jim Quinlan <james.quinlan@...adcom.com>, linux-pci@...r.kernel.org,
 Nicolas Saenz Julienne <nsaenz@...nel.org>,
 Bjorn Helgaas <bhelgaas@...gle.com>,
 Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
 Cyril Brulebois <kibi@...ian.org>, bcm-kernel-feedback-list@...adcom.com,
 jim2101024@...il.com
Cc: Florian Fainelli <florian.fainelli@...adcom.com>,
 Lorenzo Pieralisi <lpieralisi@...nel.org>,
 Krzysztof Wilczyński <kwilczynski@...nel.org>,
 Manivannan Sadhasivam <mani@...nel.org>, Rob Herring <robh@...nel.org>,
 "moderated list:BROADCOM BCM2711/BCM2835 ARM ARCHITECTURE"
 <linux-rpi-kernel@...ts.infradead.org>,
 "moderated list:BROADCOM BCM2711/BCM2835 ARM ARCHITECTURE"
 <linux-arm-kernel@...ts.infradead.org>,
 open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] PCI: brcmstb: Add a way to indicate if PCIe bridge is
 active

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 <james.quinlan@...adcom.com>

Reviewed-by: Florian Fainelli <florian.fainelli@...adcom.com>
-- 
Florian