From: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
To: Bjorn Helgaas <helgaas@kernel.org>,
David Airlie <airlied@linux.ie>, Daniel Vetter <daniel@ffwll.ch>,
Maxime Ripard <mripard@kernel.org>,
Thomas Zimmermann <tzimmermann@suse.de>
Cc: linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
dri-devel@lists.freedesktop.org,
Bjorn Helgaas <bhelgaas@google.com>,
Xuefeng Li <lixuefeng@loongson.cn>,
Huacai Chen <chenhuacai@loongson.cn>
Subject: Re: [PATCH v8 00/10] vgaarb: Rework default VGA device selection
Date: Tue, 1 Feb 2022 16:46:33 +0100 [thread overview]
Message-ID: <b0a06a30-f479-df9f-980c-b789f0f26ce9@linux.intel.com> (raw)
In-Reply-To: <20220131222342.GA517488@bhelgaas>
Hey,
Op 31-01-2022 om 23:23 schreef Bjorn Helgaas:
> [+to Maarten, Maxime, Thomas; beginning of thread:
> https://lore.kernel.org/r/20220106000658.243509-1-helgaas@kernel.org]
>
> On Wed, Jan 05, 2022 at 06:06:48PM -0600, Bjorn Helgaas wrote:
>> From: Bjorn Helgaas <bhelgaas@google.com>
>>
>> Current default VGA device selection fails in some cases because part of it
>> is done in the vga_arb_device_init() subsys_initcall, and some arches
>> enumerate PCI devices in pcibios_init(), which runs *after* that.
> Where are we at with this series? Is there anything I can do to move
> it forward?
>
> Bjorn
Hi Bjorn,
I'm afraid that I don't understand the vga arbiter or the vga code well enough to review.
Could you perhaps find someone who could review?
I see Chen wrote some patches and tested, so perhaps they could?
~Maarten
>> For example:
>>
>> - On BMC system, the AST2500 bridge [1a03:1150] does not implement
>> PCI_BRIDGE_CTL_VGA. This is perfectly legal but means the legacy VGA
>> resources won't reach downstream devices unless they're included in the
>> usual bridge windows.
>>
>> - vga_arb_select_default_device() will set a device below such a bridge
>> as the default VGA device as long as it has PCI_COMMAND_IO and
>> PCI_COMMAND_MEMORY enabled.
>>
>> - vga_arbiter_add_pci_device() is called for every VGA device, either at
>> boot-time or at hot-add time, and it will also set the device as the
>> default VGA device, but ONLY if all bridges leading to it implement
>> PCI_BRIDGE_CTL_VGA.
>>
>> - This difference between vga_arb_select_default_device() and
>> vga_arbiter_add_pci_device() means that a device below an AST2500 or
>> similar bridge can only be set as the default if it is enumerated
>> before vga_arb_device_init().
>>
>> - On ACPI-based systems, PCI devices are enumerated by acpi_init(), which
>> runs before vga_arb_device_init().
>>
>> - On non-ACPI systems, like on MIPS system, they are enumerated by
>> pcibios_init(), which typically runs *after* vga_arb_device_init().
>>
>> This series consolidates all the default VGA device selection in
>> vga_arbiter_add_pci_device(), which is always called after enumerating a
>> PCI device.
>>
>> Almost all the work here is Huacai's. I restructured it a little bit and
>> added a few trivial patches on top.
>>
>> I'd like to move vgaarb.c to drivers/pci eventually, but there's another
>> initcall ordering snag that needs to be resolved first, so this leaves
>> it where it is.
>>
>> Bjorn
>>
>> Version history:
>> V0 original implementation as final quirk to set default device.
>> https://lore.kernel.org/r/20210514080025.1828197-6-chenhuacai@loongson.cn
>>
>> V1 rework vgaarb to do all default device selection in
>> vga_arbiter_add_pci_device().
>> https://lore.kernel.org/r/20210705100503.1120643-1-chenhuacai@loongson.cn
>>
>> V2 move arbiter to PCI subsystem, fix nits.
>> https://lore.kernel.org/r/20210722212920.347118-1-helgaas@kernel.org
>>
>> V3 rewrite the commit log of the last patch (which is also summarized
>> by Bjorn).
>> https://lore.kernel.org/r/20210820100832.663931-1-chenhuacai@loongson.cn
>>
>> V4 split the last patch to two steps.
>> https://lore.kernel.org/r/20210827083129.2781420-1-chenhuacai@loongson.cn
>>
>> V5 split Patch-9 again and sort the patches.
>> https://lore.kernel.org/r/20210911093056.1555274-1-chenhuacai@loongson.cn
>>
>> V6 split Patch-5 again and sort the patches again.
>> https://lore.kernel.org/r/20210916082941.3421838-1-chenhuacai@loongson.cn
>>
>> V7 stop moving vgaarb to drivers/pci because of ordering issues with
>> misc_init().
>> https://lore.kernel.org/r/20211015061512.2941859-1-chenhuacai@loongson.cn
>> https://lore.kernel.org/r/CAAhV-H7FhAjM-Ha42Z1dLrE4PvC9frfyeU27KHWcyWKkMftEsA@mail.gmail.com
>>
>>
>> Bjorn Helgaas (8):
>> vgaarb: Factor out vga_select_framebuffer_device()
>> vgaarb: Factor out default VGA device selection
>> vgaarb: Move framebuffer detection to ADD_DEVICE path
>> vgaarb: Move non-legacy VGA detection to ADD_DEVICE path
>> vgaarb: Move disabled VGA device detection to ADD_DEVICE path
>> vgaarb: Remove empty vga_arb_device_card_gone()
>> vgaarb: Use unsigned format string to print lock counts
>> vgaarb: Replace full MIT license text with SPDX identifier
>>
>> Huacai Chen (2):
>> vgaarb: Move vga_arb_integrated_gpu() earlier in file
>> vgaarb: Log bridge control messages when adding devices
>>
>> drivers/gpu/vga/vgaarb.c | 311 +++++++++++++++++++--------------------
>> 1 file changed, 154 insertions(+), 157 deletions(-)
>>
>> --
>> 2.25.1
>>
next prev parent reply other threads:[~2022-02-01 15:46 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-06 0:06 [PATCH v8 00/10] vgaarb: Rework default VGA device selection Bjorn Helgaas
2022-01-06 0:06 ` [PATCH v8 01/10] vgaarb: Move vga_arb_integrated_gpu() earlier in file Bjorn Helgaas
2022-01-06 0:06 ` [PATCH v8 02/10] vgaarb: Factor out vga_select_framebuffer_device() Bjorn Helgaas
2022-01-06 0:06 ` [PATCH v8 03/10] vgaarb: Factor out default VGA device selection Bjorn Helgaas
2022-01-06 0:06 ` [PATCH v8 04/10] vgaarb: Move framebuffer detection to ADD_DEVICE path Bjorn Helgaas
2022-01-06 6:44 ` Huacai Chen
2022-01-06 16:20 ` Bjorn Helgaas
2022-01-25 2:51 ` Huacai Chen
2022-01-25 15:38 ` Bjorn Helgaas
2022-01-26 2:25 ` Huacai Chen
2022-01-06 0:06 ` [PATCH v8 05/10] vgaarb: Move non-legacy VGA " Bjorn Helgaas
2022-01-06 0:06 ` [PATCH v8 06/10] vgaarb: Move disabled VGA device " Bjorn Helgaas
2022-01-06 0:06 ` [PATCH v8 07/10] vgaarb: Remove empty vga_arb_device_card_gone() Bjorn Helgaas
2022-01-06 0:06 ` [PATCH v8 08/10] vgaarb: Log bridge control messages when adding devices Bjorn Helgaas
2022-01-06 0:06 ` [PATCH v8 09/10] vgaarb: Use unsigned format string to print lock counts Bjorn Helgaas
2022-01-06 0:06 ` [PATCH v8 10/10] vgaarb: Replace full MIT license text with SPDX identifier Bjorn Helgaas
2022-01-06 16:30 ` [PATCH v8 00/10] vgaarb: Rework default VGA device selection Bjorn Helgaas
2022-01-08 3:26 ` Huacai Chen
2022-01-31 22:23 ` Bjorn Helgaas
2022-02-01 15:46 ` Maarten Lankhorst [this message]
2022-02-07 17:59 ` Bjorn Helgaas
2022-02-08 2:14 ` Huacai Chen
2022-02-14 16:19 ` Bjorn Helgaas
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=b0a06a30-f479-df9f-980c-b789f0f26ce9@linux.intel.com \
--to=maarten.lankhorst@linux.intel.com \
--cc=airlied@linux.ie \
--cc=bhelgaas@google.com \
--cc=chenhuacai@loongson.cn \
--cc=daniel@ffwll.ch \
--cc=dri-devel@lists.freedesktop.org \
--cc=helgaas@kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-pci@vger.kernel.org \
--cc=lixuefeng@loongson.cn \
--cc=mripard@kernel.org \
--cc=tzimmermann@suse.de \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).