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:   Wed, 13 Jun 2018 11:50:19 -0400
From:   okaya@...eaurora.org
To:     Ard Biesheuvel <ard.biesheuvel@...aro.org>
Cc:     "open list:EFIFB FRAMEBUFFER DRIVER" <linux-fbdev@...r.kernel.org>,
        Timur Tabi <timur@...eaurora.org>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        linux-arm-msm@...r.kernel.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 2018-06-13 11:45, Ard Biesheuvel wrote:
> On 18 May 2018 at 16:17, Sinan Kaya <okaya@...eaurora.org> wrote:
>> A host bridge is allowed to remap BAR addresses using _TRA attribute 
>> in
>> _CRS windows.
>> 
>> pci_bus 0000:00: root bus resource [mem 0x80100100000-0x8011fffffff 
>> window] (bus address [0x00100000-0x1fffffff])
>> pci 0000:02:00.0: reg 0x10: [mem 0x8011e000000-0x8011effffff]
>> 
>> When a VGA device is behind such a host bridge and the resource is
>> translated efifb driver is trying to do ioremap against bus address
>> rather than the resource address and is failing to probe.
>> 
>> efifb: probing for efifb
>> efifb: cannot reserve video memory at 0x1e000000
>> efifb: framebuffer at 0x1e000000, using 1920k, total 1875k
>> efifb: mode is 800x600x32, linelength=3200, pages=1
>> efifb: scrolling: redraw
>> efifb: Truecolor: size=8:8:8:8, shift=24:16:8:0
>> 
>> Use the host bridge offset information to convert bus address to
>> resource address in the fixup.
>> 
>> Signed-off-by: Sinan Kaya <okaya@...eaurora.org>
> 
> Reviewed-by: Ard Biesheuvel <ard.biesheuvel@...aro.org>
> 
> Bartlomiej, could you please take these via the fbdev tree for v4.19?
> Peter already gave his ack but Sinan dropped it (presumably because of
> the split in v2)
> 
> Sinan, does this need to go to -stable? I.e., has it ever worked 
> before?
> 

Yes, it needs to go to stable. It never worked before. Issue was found 
during a graphics bring up with AST driver.

It needs a 32 bit graphics card and a 32 bit translating host bridge to 
hit the issue.

> 
> 
>> ---
>>  drivers/video/fbdev/efifb.c | 5 +++++
>>  1 file changed, 5 insertions(+)
>> 
>> diff --git a/drivers/video/fbdev/efifb.c b/drivers/video/fbdev/efifb.c
>> index 6daac8d..429cc85 100644
>> --- a/drivers/video/fbdev/efifb.c
>> +++ b/drivers/video/fbdev/efifb.c
>> @@ -431,6 +431,7 @@ static void efifb_fixup_resources(struct pci_dev 
>> *dev)
>>                 .end = screen_info.lfb_base + screen_info.lfb_size - 
>> 1,
>>                 .flags = IORESOURCE_MEM,
>>         };
>> +       struct pci_bus_region region;
>>         int i;
>> 
>>         if (efifb_pci_dev || screen_info.orig_video_isVGA != 
>> VIDEO_TYPE_EFI)
>> @@ -442,6 +443,10 @@ static void efifb_fixup_resources(struct pci_dev 
>> *dev)
>>         if (!screen_res.start)
>>                 return;
>> 
>> +       region.start = screen_res.start;
>> +       region.end = screen_res.end;
>> +       pcibios_bus_to_resource(dev->bus, &screen_res, &region);
>> +
>>         for (i = 0; i <= PCI_STD_RESOURCE_END; i++) {
>>                 struct resource *res = &dev->resource[i];
>> 
>> --
>> 2.7.4
>> 
>> 
>> _______________________________________________
>> linux-arm-kernel mailing list
>> linux-arm-kernel@...ts.infradead.org
>> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

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