From: Ard Biesheuvel <ard.biesheuvel@linaro.org>
To: Bjorn Helgaas <helgaas@kernel.org>
Cc: Sinan Kaya <okaya@codeaurora.org>,
"open list:EFIFB FRAMEBUFFER DRIVER"
<linux-fbdev@vger.kernel.org>,
Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
linux-arm-msm@vger.kernel.org, Timur Tabi <timur@codeaurora.org>,
open list <linux-kernel@vger.kernel.org>,
"open list:FRAMEBUFFER LAYER" <dri-devel@lists.freedesktop.org>,
Peter Jones <pjones@redhat.com>,
linux-arm-kernel <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH V2 2/2] efi/fb: Convert PCI bus address to resource if translated by the bridge
Date: Fri, 22 Jun 2018 13:21:29 +0200 [thread overview]
Message-ID: <CAKv+Gu_voOZ7YUL8pckww4mTt4PVcu7y69mf-z7ZZe1bJ81Shw@mail.gmail.com> (raw)
In-Reply-To: <20180619222921.GA90490@bhelgaas-glaptop.roam.corp.google.com>
On 20 June 2018 at 00:29, Bjorn Helgaas <helgaas@kernel.org> wrote:
> Minor subject nit: From the caller's point of view, we must convert a bus
> address to a resource *always* (the caller has no knowledge of "whether it
> is translated by the host bridge").
>
> On Fri, May 18, 2018 at 10:17:51AM -0400, Sinan Kaya wrote:
>> A host bridge is allowed to remap BAR addresses using _TRA attribute in
>> _CRS windows.
>
> Also, _TRA/_CRS are ACPI-specific terms and non-ACPI host bridges can
> also do the same sort of translation. Another trivial nit.
>
>> 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@codeaurora.org>
>
> Reviewed-by: Bjorn Helgaas <bhelgaas@google.com>
>
> Thanks a lot for fixing this!
>
Apologies for only bringing this up now, but I think this patch is
wrong after all.
screen_info.lfb_base is supposed to be a CPU address, and so
translating it like this is wrong. If you end up with a PCI address
here, you have made a mistake in hacking support for PCI outbound
translations into UEFI. Other users such as UEFI itself or GRUB will
treat this as a CPU physical address as well, so the kernel should not
treat it any differently.
>> ---
>> 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, ®ion);
>> +
>> 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@lists.infradead.org
>> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2018-06-22 11:21 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-18 14:17 [PATCH V2 1/2] efi/fb: Simplify fixup code to prefer struct resource Sinan Kaya
2018-05-18 14:17 ` [PATCH V2 2/2] efi/fb: Convert PCI bus address to resource if translated by the bridge Sinan Kaya
2018-06-13 14:22 ` Sinan Kaya
2018-06-13 15:06 ` Ard Biesheuvel
2018-06-13 15:17 ` okaya
2018-06-13 15:22 ` Ard Biesheuvel
2018-06-13 15:29 ` okaya
2018-06-13 15:45 ` Ard Biesheuvel
2018-06-13 15:50 ` okaya
2018-06-13 16:08 ` Bartlomiej Zolnierkiewicz
2018-06-22 7:54 ` Ard Biesheuvel
[not found] ` <CGME20180622100749eucas1p2a47cfba3b4d3d5004e9a0068917d5616@eucas1p2.samsung.com>
2018-06-22 10:07 ` Bartlomiej Zolnierkiewicz
[not found] ` <CGME20180622101111eucas1p119946679a7686911744b1296c2796b15@eucas1p1.samsung.com>
2018-06-22 10:11 ` Bartlomiej Zolnierkiewicz
2018-06-19 22:29 ` Bjorn Helgaas
2018-06-22 11:21 ` Ard Biesheuvel [this message]
2018-06-22 13:52 ` Sinan Kaya
2018-06-22 13:55 ` Ard Biesheuvel
2018-06-22 18:01 ` Ard Biesheuvel
2018-06-22 18:30 ` Sinan Kaya
2018-06-22 19:29 ` Ard Biesheuvel
2018-06-25 8:20 ` Ard Biesheuvel
2018-06-25 15:52 ` okaya
2018-06-25 17:28 ` Sinan Kaya
2018-06-25 17:29 ` Ard Biesheuvel
2018-06-25 17:31 ` Sinan Kaya
2018-06-13 15:42 ` [PATCH V2 1/2] efi/fb: Simplify fixup code to prefer struct resource Ard Biesheuvel
2018-06-22 10:11 ` Bartlomiej Zolnierkiewicz
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