linux-kernel - Re: [PATCH V2 2/2] efi/fb: Convert PCI bus address to resource if translated by the bridge

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Date:   Fri, 22 Jun 2018 14:30:10 -0400
From:   Sinan Kaya <okaya@...eaurora.org>
To:     Ard Biesheuvel <ard.biesheuvel@...aro.org>
Cc:     Bjorn Helgaas <helgaas@...nel.org>,
        "open list:EFIFB FRAMEBUFFER DRIVER" <linux-fbdev@...r.kernel.org>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        linux-arm-msm@...r.kernel.org, Timur Tabi <timur@...eaurora.org>,
        open list <linux-kernel@...r.kernel.org>,
        "open list:FRAMEBUFFER LAYER" <dri-devel@...ts.freedesktop.org>,
        Peter Jones <pjones@...hat.com>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH V2 2/2] efi/fb: Convert PCI bus address to resource if
 translated by the bridge

On 6/22/2018 2:01 PM, Ard Biesheuvel wrote:
>> Yes, it is part of the PCI I/O protocol definition. FrameBufferBase is
>> described as
>>
>> """
>> Base address of graphics linear frame buffer. Info contains
>> information required to allow software to draw directly to the
>> frame buffer without using Blt().Offset zero in
>> FrameBufferBase represents the upper left pixel of the
>> display.
>> """
> I just tried AMD Radeon and NVidia graphics cards on a system with
> non-1:1 mapped MMIO windows, and in both cases, the GOP protocol
> structure is populated correctly, i.e., using the CPU address not the
> PCIe address.
> 
> EDK2 only recently gained support for MMIO translation in the host
> bridge driver, so I so wonder if this is a platform issue rather than
> a driver issue. It may be worth a try to dump the results of
> GetBarAttributes() of all PCI I/O protocol instances (either in UEFI
> or in the stub), to double check that the correct values are returned.
> 

Thanks for checking out other platforms. I'll mark the issue as a BIOS
issue and bounce your feedback to the BIOS provider.

Let's hold onto this patch for the moment.

-- 
Sinan Kaya
Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.