Re: [PATCH 0/2] x86, ia64: Move EFI_FB vga_default_device() initialization to pci_vga_fixup()

["Bruno Prémont" <bonbons@linux-vserver.org>]

On Wed, 20 Aug 2014 07:55:08 +0200 Bruno Prémont wrote:
> On Tue, 19 Aug 2014 17:45:00 +0200 Andreas Noever wrote:
> > On Sat, Aug 16, 2014 at 7:21 PM, Bruno Prémont wrote:
> > > This series improves on commit 20cde694027e (x86, ia64: Move EFI_FB
> > > vga_default_device() initialization to pci_vga_fixup()):
> > > - cleanup remaining but always-true #ifndefs
> > > - fix boot regression on dual-GPU Macs
> > >
> > > Andreas, can you please test this series? It is a modification from
> > > previous testing patch that should still work fine for you.
> > > That testing patch would have been failing X startup on old BIOS systems
> > > booted with vga=normal (or otherwise in VGA text mode).
> > >
> > >
> > > Greg, in case you have scheduled above-mentioned commit for your next
> > > stable iteration, please hold it back in the queue until this follow-up
> > > has landed and can be included within the same stable update as alone
> > > that patch regresses for Macs with dual-GPU and using efifb.
> > >
> > > Bruno
> > 
> > Fails again (with and without efifb).
> > 
> > The vga_set_default_device in vga_arbiter_add_pci_device is at fault.
> > It sets the boot video device to intel. Removing it makes the system
> > bootable again.
> 
> Could you provide your whole kernel log? I would like to understand
> how your vga devices are setup and why it starts the wrong way.
> 
> If you can grab kernel log from both working and failing setups it
> would be even better. The failing one is interesting for where exactly it
> starts failing at boot.

While collecting debug logs, please apply following patch to get
PCI command and bridge control registers as configured when vgaarb looks
at them.



diff --git a/drivers/gpu/vga/vgaarb.c b/drivers/gpu/vga/vgaarb.c
index af02597..8c8e7af 100644
--- a/drivers/gpu/vga/vgaarb.c
+++ b/drivers/gpu/vga/vgaarb.c
@@ -554,6 +554,7 @@ static bool vga_arbiter_add_pci_device(struct pci_dev *pdev)
 	 * clear that below if the bridge isn't forwarding
 	 */
 	pci_read_config_word(pdev, PCI_COMMAND, &cmd);
+	pr_info("vgaarb: PCI:%s PCI_COMMAND=%04x\n", pci_name(pdev), (unsigned int)cmd);
 	if (cmd & PCI_COMMAND_IO)
 		vgadev->owns |= VGA_RSRC_LEGACY_IO;
 	if (cmd & PCI_COMMAND_MEMORY)
@@ -567,6 +568,7 @@ static bool vga_arbiter_add_pci_device(struct pci_dev *pdev)
 			u16 l;
 			pci_read_config_word(bridge, PCI_BRIDGE_CONTROL,
 					     &l);
+			pr_info("vgaarb: PCI:%s, bridge PCI:%s PCI_BRIDGE_CONTROL=%04x\n", pci_name(pdev), pci_name(bridge), (unsigned int)l);
 			if (!(l & PCI_BRIDGE_CTL_VGA)) {
 				vgadev->owns = 0;
 				break;