The HiSilicon D05 board has some PCI bridges (PCI ID 19e5:1610) that
are not spec-compliant: the VGA Enable bit is hardwired to 0 and
writes do not change it.
The HiSilicon engineers report that the bridge does not forward the
0xa0000-0xbffff mem range and the 0x3b0-0x3bb and 0x3c0-0x3df I/O
ranges.
Because the VGA Enable bit is hardwired to 0, the VGA arbiter refuses
to mark any card behind it as the boot device. This breaks Xorg
auto-detection.
However, the hibmc VGA card (PCI ID 19e5:1711) has been tested and is
known to work when behind these bridges. (It does not require the
legacy resources to operate.)
Provide a quirk so that this combination of bridge and card is eligible
to be the default VGA card. This fixes Xorg auto-detection on the D05.
Cc: Xinliang Liu <z.liuxinliang@xxxxxxxxxxxxx>
Cc: Rongrong Zou <zourongrong@xxxxxxxxx>
Signed-off-by: Daniel Axtens <dja@xxxxxxxxxx>
---
v3: update commit message and comment with information from HW engineers
---
drivers/pci/quirks.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 46 insertions(+)
diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index 16e6cd86ad71..86d7c848f3e2 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -25,6 +25,7 @@
#include <linux/sched.h>
#include <linux/ktime.h>
#include <linux/mm.h>
+#include <linux/vgaarb.h>
#include <asm/dma.h> /* isa_dma_bridge_buggy */
#include "pci.h"
@@ -4664,3 +4665,48 @@ static void quirk_intel_no_flr(struct pci_dev *dev)
}
DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, 0x1502, quirk_intel_no_flr);
DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, 0x1503, quirk_intel_no_flr);
+
+/*
+ * The hibmc card on a HiSilicon D05 board sits behind a non-compliant
+ * bridge. The bridge has the PCI_BRIDGE_CTL_VGA config bit fixed at 0
+ * in hardware. This prevents the vgaarb from marking a card behind it
+ * as boot VGA device.
+ *
+ * However, the hibmc card is known to still work, so if we have that
+ * card behind that particular bridge (19e5:1610), mark it as the
+ * default device if none has been detected.
+ */
+static void hibmc_fixup_vgaarb(struct pci_dev *pdev)
+{
+ struct pci_dev *bridge;
+ struct pci_bus *bus;
+ u16 config;
+
+ bus = pdev->bus;
+ bridge = bus->self;
+ if (!bridge)
+ return;
+
+ if (!pci_is_bridge(bridge))
+ return;
+
+ if (bridge->vendor != PCI_VENDOR_ID_HUAWEI ||
+ bridge->device != 0x1610)
+ return;
+
+ pci_read_config_word(bridge, PCI_BRIDGE_CONTROL,
+ &config);
+ if (config & PCI_BRIDGE_CTL_VGA) {
+ /*
+ * Weirdly, this bridge *is* spec compliant, so bail
+ * and let vgaarb do its job
+ */
+ return;
+ }
+
+ if (vga_default_device())
+ return;
+
+ vga_set_default_device(pdev);
+}
+DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_HUAWEI, 0x1711, hibmc_fixup_vgaarb);
--
2.11.0
