> -----Original Message----- > From: Z.q. Hou <zhiqiang.hou@xxxxxxx> > Sent: Wednesday, October 21, 2020 4:48 PM > To: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>; Richard Zhu > <hongxing.zhu@xxxxxxx> > Cc: Kishon Vijay Abraham I <kishon@xxxxxx>; Bjorn Helgaas > <helgaas@xxxxxxxxxx>; linux-kernel@xxxxxxxxxxxxxxx; linux-pci@xxxxxxxxxxxxxxx; > robh@xxxxxxxxxx; bhelgaas@xxxxxxxxxx; gustavo.pimentel@xxxxxxxxxxxx > Subject: RE: [PATCH] PCI: dwc: Added link up check in map_bus of > dw_child_pcie_ops > > Hi Lorenzo and Richard, > > > -----Original Message----- > > From: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx> > > Sent: 2020年10月20日 17:55 > > To: Z.q. Hou <zhiqiang.hou@xxxxxxx> > > Cc: Kishon Vijay Abraham I <kishon@xxxxxx>; Bjorn Helgaas > > <helgaas@xxxxxxxxxx>; linux-kernel@xxxxxxxxxxxxxxx; > > linux-pci@xxxxxxxxxxxxxxx; robh@xxxxxxxxxx; bhelgaas@xxxxxxxxxx; > > gustavo.pimentel@xxxxxxxxxxxx > > Subject: Re: [PATCH] PCI: dwc: Added link up check in map_bus of > > dw_child_pcie_ops > > > > On Tue, Oct 20, 2020 at 02:13:13AM +0000, Z.q. Hou wrote: > > > > [...] > > > > > > > For NXP Layerscape platforms (the ls1028a and ls2088a are also > > > > > NXP > > > > Layerscape platform), as the error response to AXI/AHB was > > > > enabled, it will get UR error and trigger SError on AXI bus when > > > > it accesses a non-existent BDF on a link down bus. I'm not clear > > > > about how it happens on dra7xxx and imx6, since they doesn't > > > > enable the error > > response to AXI/AHB. > > > > > > > > That's exactly the case with DRA7xx as the error response is > > > > enabled by default in the platform integration. > > > > > > Got feedback from the imx6 owner that imx6 like the dra7xx has the > > > error response enabled by default. Now it's clear that the problem > > > on all these platforms is the same. > > > > On IMX6, enabled by default and read-only ? Or it can be changed ? > > The AXI/AHB Bridge Slave Error Response Register is a common register of DWC IP, > so I think it should be writeable. Richard, can you help to confirm? > This register is writable, but only some bits of this reg can be wrote. Best Regards Richard Zhu > > What's the plan for layerscape on this matter ? > > I trend to change it back to the default error response behavior so that won't > cause any error on CFG access, and have sent out the patch. > And for the link up check before CFG accesses, in the DWC databoot (4.40a), it > requires link up check before generating CFG requests, so need Gustavo help to > make sure the reason of this requirement, any potential impact without the link > up check. > > Thanks, > Zhiqiang > > > > Lorenzo
