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Subject: Re: [PATCH 1/1] PCI: Add pci reset quirk for Nvidia GPUs
To:     Shanker Donthineni <sdonthineni@nvidia.com>,
        Bjorn Helgaas <bhelgaas@google.com>,
        Alex Williamson <alex.williamson@redhat.com>
Cc:     linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
        Vikram Sethi <vsethi@nvidia.com>
References: <20210423145402.14559-1-sdonthineni@nvidia.com>
From:   Sinan Kaya <okaya@kernel.org>
Message-ID: <ff4812ba-ec1d-9462-0cbd-029635af3267@kernel.org>
Date:   Fri, 23 Apr 2021 11:12:05 -0400
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+Alex,

On 4/23/2021 10:54 AM, Shanker Donthineni wrote:
> +static int reset_nvidia_gpu_quirk(struct pci_dev *dev, int probe)
> +{
> +#ifdef CONFIG_ACPI
> +	acpi_handle handle = ACPI_HANDLE(&dev->dev);
> +
> +	/*
> +	 * Check for the affected devices' ID range. If device is not in
> +	 * the affected range, return -ENOTTY indicating no device
> +	 * specific reset method is available.
> +	 */
> +	if ((dev->device & 0xffc0) != 0x2340)
> +		return -ENOTTY;
> +
> +	/*
> +	 * Return -ENOTTY indicating no device-specific reset method if _RST
> +	 * method is not defined
> +	 */
> +	if (!handle || !acpi_has_method(handle, "_RST"))
> +		return -ENOTTY;
> +
> +	/* Return 0 for probe phase indicating that we can reset this device */
> +	if (probe)
> +		return 0;
> +
> +	/* Invoke _RST() method to perform the device-specific reset */
> +	if (ACPI_FAILURE(acpi_evaluate_object(handle, "_RST", NULL, NULL))) {
> +		pci_warn(dev, "Failed to reset the device\n");
> +		return -EINVAL;
> +	}
> +	return 0;
> +#else
> +	return -ENOTTY;
> +#endif
> +}

Interesting, some pieces of this function (especially the ACPI _RST)
could be generalized.