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Message-ID: <49618cce-8c3f-7f25-20b1-eecfc3c70cd0@loongson.cn>
Date:   Mon, 24 Jul 2023 19:56:35 +0800
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Subject: Re: [PATCH v3 4/9] PCI/VGA: Improve the default VGA device selection
To:     Bjorn Helgaas <helgaas@kernel.org>,
        Sui Jingfeng <sui.jingfeng@linux.dev>
Cc:     David Airlie <airlied@gmail.com>, amd-gfx@lists.freedesktop.org,
        dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org,
        intel-gfx@lists.freedesktop.org, kvm@vger.kernel.org,
        linux-pci@vger.kernel.org, linux-fbdev@vger.kernel.org,
        Alex Deucher <alexander.deucher@amd.com>,
        Christian Konig <christian.koenig@amd.com>,
        Pan Xinhui <Xinhui.Pan@amd.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>,
        Mario Limonciello <mario.limonciello@amd.com>,
        Lijo Lazar <lijo.lazar@amd.com>,
        YiPeng Chai <YiPeng.Chai@amd.com>,
        Bokun Zhang <Bokun.Zhang@amd.com>,
        Likun Gao <Likun.Gao@amd.com>,
        Ville Syrjala <ville.syrjala@linux.intel.com>,
        Jason Gunthorpe <jgg@ziepe.ca>,
        Kevin Tian <kevin.tian@intel.com>,
        Cornelia Huck <cohuck@redhat.com>,
        Yishai Hadas <yishaih@nvidia.com>,
        Abhishek Sahu <abhsahu@nvidia.com>,
        Yi Liu <yi.l.liu@intel.com>,
        Jani Nikula <jani.nikula@intel.com>
References: <20230719193233.GA511659@bhelgaas>
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From:   suijingfeng <suijingfeng@loongson.cn>
In-Reply-To: <20230719193233.GA511659@bhelgaas>
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Hi,


I was too hurry reply to you. I'm may miss the point for part of your 
reviews, Sorry.


On 2023/7/20 03:32, Bjorn Helgaas wrote:
> CONFIG_DRM_AST is a tristate.  We're talking about identifying the
> boot-time console device.

Yes, my patch will only works *after* the module gets loaded successfully.

But generally, vgaarb will select a default boot device before my patch taking into effect.

I means that vgaarb will select a default boot device by calling vga_arbiter_add_pci_device() function.


In practice, I still not notice any obvious problems.

I'm lack the knowledge about the boot-time console,

what is the potential problems with such a condition?


>   So if CONFIG_DRM_AST=m, I guess we don't
> get the benefit of the new callback unless the module gets loaded?

Yes, my approach will not works until the device driver kernel module 
gets loaded successfully.

So what's the problem with such a situation, do you see something weird ?