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Date: Tue, 22 Apr 2025 12:41:56 -0500
From: Bjorn Helgaas <helgaas@kernel.org>
To: Marc Zyngier <maz@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org, linux-pci@vger.kernel.org,
	devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
	asahi@lists.linux.dev, Alyssa Rosenzweig <alyssa@rosenzweig.io>,
	Janne Grunau <j@jannau.net>, Hector Martin <marcan@marcan.st>,
	Sven Peter <sven@svenpeter.dev>,
	Bjorn Helgaas <bhelgaas@google.com>,
	Lorenzo Pieralisi <lpieralisi@kernel.org>,
	Krzysztof =?utf-8?Q?Wilczy=C5=84ski?= <kw@linux.com>,
	Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>,
	Rob Herring <robh@kernel.org>,
	Krzysztof Kozlowski <krzk+dt@kernel.org>,
	Mark Kettenis <mark.kettenis@xs4all.nl>
Subject: Re: [PATCH v3 07/13] PCI: apple: Move away from INTMSK{SET,CLR} for
 INTx and private interrupts
Message-ID: <20250422174156.GA344533@bhelgaas>
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In-Reply-To: <20250401091713.2765724-8-maz@kernel.org>

On Tue, Apr 01, 2025 at 10:17:07AM +0100, Marc Zyngier wrote:
> T602x seems to have dropped the rather useful SET/CLR accessors
> to the masking register.
> 
> Instead, let's use the mask register directly, and wrap it with
> a brand new spinlock. No, this isn't moving in the right direction.

> @@ -261,14 +262,16 @@ static void apple_port_irq_mask(struct irq_data *data)
>  {
>  	struct apple_pcie_port *port = irq_data_get_irq_chip_data(data);
>  
> -	writel_relaxed(BIT(data->hwirq), port->base + PORT_INTMSKSET);
> +	guard(raw_spinlock_irqsave)(&port->lock);
> +	rmw_set(BIT(data->hwirq), port->base + PORT_INTMSK);

sparse v0.6.4-39-gce1a6720 complains about this (and similar usage
elsewhere):

  $ make C=2 drivers/pci/
  drivers/pci/controller/pcie-apple.c:311:13: warning: context imbalance in 'apple_port_irq_mask' - wrong count at exit
  drivers/pci/controller/pcie-apple.c:319:13: warning: context imbalance in 'apple_port_irq_unmask' - wrong count at exit

But I guess we just have to live with this for now until somebody
makes sparse smarter:

https://lore.kernel.org/linux-sparse/CAHk-=wiVDZejo_1BhOaR33qb=pny7sWnYtP4JUbRTXkXCkW6jA@mail.gmail.com/

Nothing to do, just "huh".

Bjorn