Bjorn Helgaas <helgaas@xxxxxxxxxx> writes: > Hi Alexander, Hi Bjorn, > On Tue, Sep 19, 2017 at 05:51:36PM +0300, Alexander Shishkin wrote: >> On some intergrations of the Intel TH the reported size of RTIT_BAR > > s/intergrations/integrations/ Oops. > What is "TH"? If there's a public spec for it, can you include a > reference here? Intel Trace Hub, https://software.intel.com/sites/default/files/managed/d3/3c/intel-th-developer-manual.pdf There's an overview at Documentation/trace/intel_th.txt. > I guess this is an erratum, since the device responds to more MMIO > space than it advertises via the BAR. Can you include a reference to > the published erratum? There's no erratum at the moment, unfortunately. >> doesn't match its actual size, which leads to overlaps with other >> devices' resources. > > So I suppose the BIOS relies on the size advertised via the BAR, > assigns it to be just below the XHCI space, and now both the TH and > XHCI respond there? I assume this causes some sort of "unexpected > response" error? Is there a bug report about this? What does it look > like when a user hits this? I'm trying to make this fix discoverable > to users who might trip over the problem. When the intel_th pci device gets enabled (on modprobe, for example), XHCI starts seeing 0xffffffff in its MMIO registers, which makes it go xhci_hcd: xHCI host controller not responding, assume dead xhci_hcd: xHC not responding in xhci_irq, assume controller is dead xhci_hcd: HC died; cleaning up followed by disappearance of keyboards and user's profound confusion. I'll make sure to mention all this in the commit message. >> For this reason, we need to resize the RTIT_BAR on Denverton where >> it would overlap with XHCI MMIO space. >> >> Signed-off-by: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx> >> Fixes: 5118ccd347 ("intel_th: pci: Add Denverton SOC support") > > Please use a 12-char SHA1. Will do. >> Cc: stable@xxxxxxxxxxxxxxx > > I guess this is only applicable to v4.11+, since 5118ccd34780 appeared in > v4.11-rc4? Right, my git-send-email keeps trying to CC "# v4.11+" if I leave it in the Cc: stable line. Regards, -- Alex