Re: [PATCH] PCI: mvebu: setup BAR0 to internal-regs

[Bjorn Helgaas <helgaas@kernel.org>]

On Mon, Jun 22, 2020 at 08:40:33PM +0200, Thomas Petazzoni wrote:
> On Mon, 22 Jun 2020 12:25:16 -0500
> Bjorn Helgaas <helgaas@kernel.org> wrote:
> 
> > > As a result of the requirement above, without this patch, MSI won't
> > > function and therefore some devices won't operate properly without
> > > pci=nomsi.  
> > 
> > Does that mean MSIs never worked at all with mvebu?
> 
> They definitely worked. I think what happens is that this register was
> normally setup by the vendor-specific bootloader, and thanks to
> firmware initialization, Linux had MSIs working properly.
> 
> With other bootloaders that initialize the PCIe block differently, or
> even not at all, it became clear this init was missing in Linux.

That would be very useful information to include in the commit log.

Are there any other similar bugs lurking?  Other registers where we
implicitly rely on the bootloader to do something?

Bjorn