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Date:   Thu, 8 Jun 2023 14:12:21 -0500
From:   Bjorn Helgaas <helgaas@kernel.org>
To:     Sui Jingfeng <15330273260@189.cn>
Cc:     Alex Deucher <alexander.deucher@amd.com>,
        Christian Konig <christian.koenig@amd.com>,
        Pan Xinhui <Xinhui.Pan@amd.com>,
        David Airlie <airlied@gmail.com>,
        Daniel Vetter <daniel@ffwll.ch>,
        Jani Nikula <jani.nikula@linux.intel.com>,
        Joonas Lahtinen <joonas.lahtinen@linux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@intel.com>,
        Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>,
        Ben Skeggs <bskeggs@redhat.com>,
        Karol Herbst <kherbst@redhat.com>,
        Lyude Paul <lyude@redhat.com>,
        Bjorn Helgaas <bhelgaas@google.com>,
        Alex Williamson <alex.williamson@redhat.com>,
        Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
        Maxime Ripard <mripard@kernel.org>,
        Thomas Zimmermann <tzimmermann@suse.de>,
        Hawking Zhang <Hawking.Zhang@amd.com>,
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        Bokun Zhang <Bokun.Zhang@amd.com>,
        Ville Syrjala <ville.syrjala@linux.intel.com>,
        Li Yi <liyi@loongson.cn>,
        Sui Jingfeng <suijingfeng@loongson.cn>,
        Jason Gunthorpe <jgg@ziepe.ca>,
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        Cornelia Huck <cohuck@redhat.com>,
        Yishai Hadas <yishaih@nvidia.com>,
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        Yi Liu <yi.l.liu@intel.com>, kvm@vger.kernel.org,
        nouveau@lists.freedesktop.org, intel-gfx@lists.freedesktop.org,
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        linux-pci@vger.kernel.org
Subject: Re: [Intel-gfx] [PATCH v3 3/4] PCI/VGA: only deal with VGA class
 devices
Message-ID: <20230608191221.GA1209912@bhelgaas>
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In-Reply-To: <20230608114322.604887-4-15330273260@189.cn>
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Start with verb and capitalize to match ("Deal only with ...")

On Thu, Jun 08, 2023 at 07:43:21PM +0800, Sui Jingfeng wrote:
> From: Sui Jingfeng <suijingfeng@loongson.cn>
> 
> vgaarb only deal with the VGA devcie(pdev->class == 0x0300), so replace the
> pci_get_subsys() function with pci_get_class(). Filter the non pci display
> device out. There no need to process the non display PCI device.

s/non pci/non-PCI/
s/non display/non-display/

This is fine, and I'll merge this, but someday I would like to get rid
of the bus_register_notifier() and call vga_arbiter_add_pci_device()
and vga_arbiter_del_pci_device() directly from the PCI core.

Or if you wanted to do that now, that would be even better :)

Bjorn

> Signed-off-by: Sui Jingfeng <suijingfeng@loongson.cn>
> ---
>  drivers/pci/vgaarb.c | 22 ++++++++++++----------
>  1 file changed, 12 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/pci/vgaarb.c b/drivers/pci/vgaarb.c
> index 7f0347f4f6fd..b0bf4952a95d 100644
> --- a/drivers/pci/vgaarb.c
> +++ b/drivers/pci/vgaarb.c
> @@ -756,10 +756,6 @@ static bool vga_arbiter_add_pci_device(struct pci_dev *pdev)
>  	struct pci_dev *bridge;
>  	u16 cmd;
>  
> -	/* Only deal with VGA class devices */
> -	if ((pdev->class >> 8) != PCI_CLASS_DISPLAY_VGA)
> -		return false;
> -
>  	/* Allocate structure */
>  	vgadev = kzalloc(sizeof(struct vga_device), GFP_KERNEL);
>  	if (vgadev == NULL) {
> @@ -1499,7 +1495,9 @@ static int pci_notify(struct notifier_block *nb, unsigned long action,
>  	struct pci_dev *pdev = to_pci_dev(dev);
>  	bool notify = false;
>  
> -	vgaarb_dbg(dev, "%s\n", __func__);
> +	/* Only deal with VGA class devices */
> +	if ((pdev->class >> 8) != PCI_CLASS_DISPLAY_VGA)
> +		return 0;
>  
>  	/* For now we're only intereted in devices added and removed. I didn't
>  	 * test this thing here, so someone needs to double check for the
> @@ -1509,6 +1507,8 @@ static int pci_notify(struct notifier_block *nb, unsigned long action,
>  	else if (action == BUS_NOTIFY_DEL_DEVICE)
>  		notify = vga_arbiter_del_pci_device(pdev);
>  
> +	vgaarb_dbg(dev, "%s: action = %lu\n", __func__, action);
> +
>  	if (notify)
>  		vga_arbiter_notify_clients();
>  	return 0;
> @@ -1533,8 +1533,8 @@ static struct miscdevice vga_arb_device = {
>  
>  static int __init vga_arb_device_init(void)
>  {
> +	struct pci_dev *pdev = NULL;
>  	int rc;
> -	struct pci_dev *pdev;
>  
>  	rc = misc_register(&vga_arb_device);
>  	if (rc < 0)
> @@ -1545,11 +1545,13 @@ static int __init vga_arb_device_init(void)
>  	/* We add all PCI devices satisfying VGA class in the arbiter by
>  	 * default
>  	 */
> -	pdev = NULL;
> -	while ((pdev =
> -		pci_get_subsys(PCI_ANY_ID, PCI_ANY_ID, PCI_ANY_ID,
> -			       PCI_ANY_ID, pdev)) != NULL)
> +	while (1) {
> +		pdev = pci_get_class(PCI_CLASS_DISPLAY_VGA << 8, pdev);
> +		if (!pdev)
> +			break;
> +
>  		vga_arbiter_add_pci_device(pdev);
> +	};
>  
>  	pr_info("loaded\n");
>  	return rc;
> -- 
> 2.25.1
>