linux-kernel - Re: [PATCH 2/3] irqchip/gic: Use 0x10000 offset to access GICC

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Message-ID: <87mscxuu6f.ffs@tglx>
Date: Thu, 03 Apr 2025 17:43:52 +0200
From: Thomas Gleixner <tglx@...utronix.de>
To: Christian Bruel <christian.bruel@...s.st.com>, maz@...nel.org,
 robh@...nel.org, krzk+dt@...nel.org, conor+dt@...nel.org,
 mcoquelin.stm32@...il.com, alexandre.torgue@...s.st.com
Cc: linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
 devicetree@...r.kernel.org, linux-stm32@...md-mailman.stormreply.com,
 Christian Bruel <christian.bruel@...s.st.com>
Subject: Re: [PATCH 2/3] irqchip/gic: Use 0x10000 offset to access GICC_DIR
 on STM32MP2

On Thu, Apr 03 2025 at 14:28, Christian Bruel wrote:

> When GIC_4KNOT64K bit in the GIC configuration register is
> 0 (64KB), address block is modified in such a way than only the

s/than/that/

> first 4KB of the GIC cpu interface are accessible with default
> offsets.
> With this bit mapping GICC_DIR register is accessible at

What's 'this bit mapping' ? This sentence does not parse.

> offset 0x10000 instead of 0x1000, thus remap accordingly

...

> +/*
> + * 8kB GICC range is not accessible with the default 4kB translation
> + * granule. 0x1000 offset is accessible at 64kB translation.
> + */

I have a hard time to map this comment to the change log, which suggests
to me that this is the other way round.

> +static bool gic_8kbaccess(void *data)
> +{
> +	struct gic_chip_data *gic = data;
> +	void __iomem *alt;
> +
> +	if (!is_hyp_mode_available())
> +		return false;
> +
> +	alt = ioremap(gic->cpu_phys_base, GIC_STM32MP2_CPU_DEACTIVATE + 4);
> +	if (!alt) {
> +		pr_err("Unable to remap GICC_DIR register\n");
> +		return false;

That's a hack because in case that the remap fails, this leaves the
thing enabled, but disfunctional.

Thanks,

        tglx