linux-kernel - Re: [PATCH v6 2/8] PCI/VGA: Deal only with VGA class devices

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Message-ID: <345c2bb9-71d8-27b9-0175-f1e55f096ed1@189.cn>
Date:   Tue, 20 Jun 2023 10:35:46 +0800
From:   Sui Jingfeng <15330273260@....cn>
To:     "Limonciello, Mario" <mario.limonciello@....com>,
        Alex Deucher <alexander.deucher@....com>,
        Christian Konig <christian.koenig@....com>,
        Pan Xinhui <Xinhui.Pan@....com>,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>,
        Jani Nikula <jani.nikula@...ux.intel.com>,
        Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@...el.com>,
        Tvrtko Ursulin <tvrtko.ursulin@...ux.intel.com>,
        Ben Skeggs <bskeggs@...hat.com>,
        Karol Herbst <kherbst@...hat.com>,
        Lyude Paul <lyude@...hat.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Alex Williamson <alex.williamson@...hat.com>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        Hawking Zhang <Hawking.Zhang@....com>,
        Lijo Lazar <lijo.lazar@....com>,
        YiPeng Chai <YiPeng.Chai@....com>,
        Andrey Grodzovsky <andrey.grodzovsky@....com>,
        Somalapuram Amaranath <Amaranath.Somalapuram@....com>,
        Bokun Zhang <Bokun.Zhang@....com>,
        Ville Syrjala <ville.syrjala@...ux.intel.com>,
        Li Yi <liyi@...ngson.cn>,
        Sui Jingfeng <suijingfeng@...ngson.cn>,
        Jason Gunthorpe <jgg@...pe.ca>,
        Kevin Tian <kevin.tian@...el.com>,
        Cornelia Huck <cohuck@...hat.com>,
        Yishai Hadas <yishaih@...dia.com>,
        Abhishek Sahu <abhsahu@...dia.com>, Yi Liu <yi.l.liu@...el.com>
Cc:     amd-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org, intel-gfx@...ts.freedesktop.org,
        nouveau@...ts.freedesktop.org, linux-pci@...r.kernel.org,
        kvm@...r.kernel.org, loongson-kernel@...ts.loongnix.cn
Subject: Re: [PATCH v6 2/8] PCI/VGA: Deal only with VGA class devices

Hi,

On 2023/6/20 02:12, Limonciello, Mario wrote:
>
> On 6/12/2023 2:25 PM, Sui Jingfeng wrote:
>> From: Sui Jingfeng <suijingfeng@...ngson.cn>
>>
>> Deal only with the VGA devcie(pdev->class == 0x0300), so replace the
>> pci_get_subsys() function with pci_get_class(). Filter the non-PCI 
>> display
>> device(pdev->class != 0x0300) out. There no need to process the 
>> non-display
>> PCI device.
>>
>> Signed-off-by: Sui Jingfeng <suijingfeng@...ngson.cn>
>> ---
> This also means that deleting a PCI device no longer needs
> to walk the list.
>
> Reviewed-by: Mario Limonciello <mario.limonciello@....com>
>

Thanks a lot.


>>   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 c1bc6c983932..22a505e877dc 100644
>> --- a/drivers/pci/vgaarb.c
>> +++ b/drivers/pci/vgaarb.c
>> @@ -754,10 +754,6 @@ 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) {
>> @@ -1500,7 +1496,9 @@ 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 != PCI_CLASS_DISPLAY_VGA << 8)
>> +        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
>> @@ -1510,6 +1508,8 @@ 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;
>> @@ -1534,8 +1534,8 @@ 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;