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

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Message-Id: <1526653072-7153-2-git-send-email-okaya@codeaurora.org>
Date:   Fri, 18 May 2018 10:17:51 -0400
From:   Sinan Kaya <okaya@...eaurora.org>
To:     linux-fbdev@...r.kernel.org, timur@...eaurora.org
Cc:     linux-arm-msm@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        Sinan Kaya <okaya@...eaurora.org>,
        Peter Jones <pjones@...hat.com>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        dri-devel@...ts.freedesktop.org (open list:FRAMEBUFFER LAYER),
        linux-kernel@...r.kernel.org (open list)
Subject: [PATCH V2 2/2] efi/fb: Convert PCI bus address to resource if translated by the bridge

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>
---
 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