From: Bjorn Helgaas <helgaas@kernel.org>
To: Sui Jingfeng <sui.jingfeng@linux.dev>
Cc: Sui Jingfeng <suijingfeng@loongson.cn>,
Thomas Zimmermann <tzimmermann@suse.de>,
linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
Maxime Ripard <mripard@kernel.org>,
dri-devel@lists.freedesktop.org,
Bjorn Helgaas <bhelgaas@google.com>,
Mario Limonciello <mario.limonciello@amd.com>
Subject: Re: [PATCH 2/4] PCI/VGA: Deal only with PCI VGA class devices
Date: Wed, 19 Jul 2023 13:07:52 -0500 [thread overview]
Message-ID: <20230719180752.GA509850@bhelgaas> (raw)
In-Reply-To: <20230718231400.GA496927@bhelgaas>
On Tue, Jul 18, 2023 at 06:14:00PM -0500, Bjorn Helgaas wrote:
> On Fri, Jun 30, 2023 at 06:17:29PM +0800, Sui Jingfeng wrote:
> > From: Sui Jingfeng <suijingfeng@loongson.cn>
> >
> > VGAARB should only care about PCI VGA class devices (pdev->class == 0x0300)
> > since only those devices might have VGA routed to them.
>
> This is not actually a question of whether VGA addresses (mem
> 0xa0000-0xbffff and io 0x3b0-0x3bb, 0x3c0-0x3df) might be *routed* to
> the device because that routing is controlled by the bridge VGA Enable
> bit, not by a device Class Code.
>
> I think the important question here is what devices will *respond* to
> those VGA addresses. The VGA arbiter works by managing bridge VGA
> Enable bits, so if we know a device doesn't respond to the VGA
> addresses, there's no point in adding a vga_device for it.
Sorry, I see that I replied to an old version of this patch. I'll go
look at this series instead:
https://lore.kernel.org/r/20230711134354.755966-1-sui.jingfeng@linux.dev
Bjorn
WARNING: multiple messages have this Message-ID (diff)
From: Bjorn Helgaas <helgaas@kernel.org>
To: Sui Jingfeng <sui.jingfeng@linux.dev>
Cc: Sui Jingfeng <suijingfeng@loongson.cn>,
linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
Maxime Ripard <mripard@kernel.org>,
dri-devel@lists.freedesktop.org,
Thomas Zimmermann <tzimmermann@suse.de>,
Bjorn Helgaas <bhelgaas@google.com>,
Mario Limonciello <mario.limonciello@amd.com>
Subject: Re: [PATCH 2/4] PCI/VGA: Deal only with PCI VGA class devices
Date: Wed, 19 Jul 2023 13:07:52 -0500 [thread overview]
Message-ID: <20230719180752.GA509850@bhelgaas> (raw)
In-Reply-To: <20230718231400.GA496927@bhelgaas>
On Tue, Jul 18, 2023 at 06:14:00PM -0500, Bjorn Helgaas wrote:
> On Fri, Jun 30, 2023 at 06:17:29PM +0800, Sui Jingfeng wrote:
> > From: Sui Jingfeng <suijingfeng@loongson.cn>
> >
> > VGAARB should only care about PCI VGA class devices (pdev->class == 0x0300)
> > since only those devices might have VGA routed to them.
>
> This is not actually a question of whether VGA addresses (mem
> 0xa0000-0xbffff and io 0x3b0-0x3bb, 0x3c0-0x3df) might be *routed* to
> the device because that routing is controlled by the bridge VGA Enable
> bit, not by a device Class Code.
>
> I think the important question here is what devices will *respond* to
> those VGA addresses. The VGA arbiter works by managing bridge VGA
> Enable bits, so if we know a device doesn't respond to the VGA
> addresses, there's no point in adding a vga_device for it.
Sorry, I see that I replied to an old version of this patch. I'll go
look at this series instead:
https://lore.kernel.org/r/20230711134354.755966-1-sui.jingfeng@linux.dev
Bjorn
next prev parent reply other threads:[~2023-07-19 18:07 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-30 10:17 [PATCH 1/4] PCI/VGA: Use unsigned type for the io_state variable Sui Jingfeng
2023-06-30 10:17 ` Sui Jingfeng
2023-06-30 10:17 ` [PATCH 2/4] PCI/VGA: Deal only with PCI VGA class devices Sui Jingfeng
2023-06-30 10:17 ` Sui Jingfeng
2023-07-18 23:14 ` Bjorn Helgaas
2023-07-18 23:14 ` Bjorn Helgaas
2023-07-19 18:07 ` Bjorn Helgaas [this message]
2023-07-19 18:07 ` Bjorn Helgaas
2023-06-30 10:17 ` [PATCH 3/4] PCI/VGA: Tidy up the code and comment format Sui Jingfeng
2023-06-30 10:17 ` Sui Jingfeng
2023-06-30 10:17 ` [PATCH 4/4] PCI/VGA: Replace full MIT license text with SPDX identifier Sui Jingfeng
2023-06-30 10:17 ` Sui Jingfeng
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