linux-kernel - Re: [PATCH v6 0/8] PCI/VGA: introduce is_boot_device function callback to vga_client

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Message-ID: <0afadc69f99a36bc9d03ecf54ff25859dbc10e28.camel@redhat.com>
Date:   Wed, 21 Jun 2023 18:11:59 -0400
From:   Lyude Paul <lyude@...hat.com>
To:     Sui Jingfeng <15330273260@....cn>,
        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>,
        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>,
        Mario Limonciello <mario.limonciello@....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 0/8] PCI/VGA: introduce is_boot_device function
 callback to vga_client_register

For the nouveau bits:

Reviewed-by: Lyude Paul <lyude@...hat.com>

On Tue, 2023-06-13 at 03:25 +0800, Sui Jingfeng wrote:
> From: Sui Jingfeng <suijingfeng@...ngson.cn>
> 
> The vga_is_firmware_default() function is arch-dependent, it's probably
> wrong if we simply remove the arch guard. As the VRAM BAR which contains
> firmware framebuffer may move, while the lfb_base and lfb_size members of
> the screen_info does not change accordingly. In short, it should take the
> re-allocation of the PCI BAR into consideration.
> 
> With the observation that device drivers or video aperture helpers may
> have better knowledge about which PCI bar contains the firmware fb,
> which could avoid the need to iterate all of the PCI BARs. But as a PCI
> function at pci/vgaarb.c, vga_is_firmware_default() is not suitable to
> make such an optimization since it is loaded too early.
> 
> There are PCI display controllers that don't have a dedicated VRAM bar,
> this function will lose its effectiveness in such a case. Luckily, the
> device driver can provide an accurate workaround.
> 
> Therefore, this patch introduces a callback that allows the device driver
> to tell the VGAARB if the device is the default boot device. Also honor
> the comment: "Clients have two callback mechanisms they can use"
> 
> Sui Jingfeng (8):
>   PCI/VGA: Use unsigned type for the io_state variable
>   PCI/VGA: Deal only with VGA class devices
>   PCI/VGA: Tidy up the code and comment format
>   PCI/VGA: Replace full MIT license text with SPDX identifier
>   video/aperture: Add a helper to detect if an aperture contains
>     firmware FB
>   PCI/VGA: Introduce is_boot_device function callback to
>     vga_client_register
>   drm/amdgpu: Implement the is_boot_device callback function
>   drm/radeon: Implement the is_boot_device callback function
> 
>  drivers/gpu/drm/amd/amdgpu/amdgpu_device.c |  12 +-
>  drivers/gpu/drm/drm_aperture.c             |  16 +++
>  drivers/gpu/drm/i915/display/intel_vga.c   |   3 +-
>  drivers/gpu/drm/nouveau/nouveau_vga.c      |   2 +-
>  drivers/gpu/drm/radeon/radeon_device.c     |  12 +-
>  drivers/pci/vgaarb.c                       | 153 +++++++++++++--------
>  drivers/vfio/pci/vfio_pci_core.c           |   2 +-
>  drivers/video/aperture.c                   |  29 ++++
>  include/drm/drm_aperture.h                 |   2 +
>  include/linux/aperture.h                   |   7 +
>  include/linux/vgaarb.h                     |  35 ++---
>  11 files changed, 184 insertions(+), 89 deletions(-)
> 

-- 
Cheers,
 Lyude Paul (she/her)
 Software Engineer at Red Hat