Date:   Mon, 27 Feb 2023 02:55:45 +0000
From:   Thomas =?utf-8?Q?Wei=C3=9Fschuh?= <thomas@t-8ch.de>
To:     Shawn Guo <shawn.guo@linaro.org>
Cc:     Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will@kernel.org>,
        Bjorn Helgaas <bhelgaas@google.com>,
        Maximilian Luz <luzmaximilian@gmail.com>,
        Lorenzo Pieralisi <lpieralisi@kernel.org>,
        linux-pci@vger.kernel.org, linux-acpi@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] arm64: PCI: Add quirk for platforms running Windows
Message-ID: <67eac531-d808-4fc8-b282-754204b4bad0@t-8ch.de>
References: <20230227021221.17980-1-shawn.guo@linaro.org>
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In-Reply-To: <20230227021221.17980-1-shawn.guo@linaro.org>
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Hi,

On Mon, Feb 27, 2023 at 10:12:21AM +0800, Shawn Guo wrote:
> diff --git a/arch/arm64/kernel/pci.c b/arch/arm64/kernel/pci.c
> index 2276689b5411..896dbd028b67 100644
> --- a/arch/arm64/kernel/pci.c
> +++ b/arch/arm64/kernel/pci.c
> @@ -109,16 +109,42 @@ int pcibios_root_bridge_prepare(struct pci_host_bridge *bridge)
>  	return 0;
>  }
>  
> +#define QCOM_DSDT_QUIRK "Host bridge windows in PNP0A03 _CRS"
> +
> +static struct acpi_platform_list qcom_platlist[] = {
        ^^^
       const

> +	/* Thinkpad X13s */
> +	{ "LENOVO", "SDM8280 ", 0, ACPI_SIG_DSDT, all_versions, QCOM_DSDT_QUIRK },
> +	/* Microsoft Surface Pro 9 (5G) and Windows Dev Kit 2023 */
> +	{ "QCOMM ", "SDM8280 ", 0, ACPI_SIG_DSDT, all_versions, QCOM_DSDT_QUIRK },
> +	/* Microsoft Surface Pro X */
> +	{ "QCOMM ", "SDM8180 ", 0, ACPI_SIG_DSDT, all_versions, QCOM_DSDT_QUIRK },
> +	{ }
> +};
> +
>  static int pci_acpi_root_prepare_resources(struct acpi_pci_root_info *ci)
>  {
>  	struct resource_entry *entry, *tmp;
>  	int status;
> +	int idx;
>  
>  	status = acpi_pci_probe_root_resources(ci);
> +
> +	/*
> +	 * Most arm64 platforms that do not run Windows describe host bridge
> +	 * registers in PNP0A03 _CRS resources, but some like Qualcomm
> +	 * Snapdragon Windows laptops describe host bridge windows in there.
> +	 * We do not want to destroy the resources for these platforms.
> +	 */
> +	idx = acpi_match_platform_list(qcom_platlist);
> +	if (idx >= 0)
> +		goto done;
> +
>  	resource_list_for_each_entry_safe(entry, tmp, &ci->resources) {
>  		if (!(entry->res->flags & IORESOURCE_WINDOW))
>  			resource_list_destroy_entry(entry);
>  	}
> +
> +done:
>  	return status;
>  }
>  
> -- 
> 2.17.1
>