Re: [PATCH 1/2] PCI: dwc: Program device-id

[Shawn Lin]

在 2025/11/29 星期六 15:34, Manivannan Sadhasivam 写道:
> On Fri, Nov 28, 2025 at 09:03:52AM +0800, Shawn Lin wrote:
> > 在 2025/11/27 星期四 23:30, Sushrut Shree Trivedi 写道:
> > > For some controllers, HW doesn't program the correct device-id
> > > leading to incorrect identification in lspci. For ex, QCOM
> > > controller SC7280 uses same device id as SM8250. This would
> > > cause issues while applying controller specific quirks.
> > >
> > > So, program the correct device-id after reading it from the
> > > devicetree.
> > >
> > > Signed-off-by: Sushrut Shree Trivedi <sushrut.trivedi@xxxxxxxxxxxxxxxx>
> > > ---
> > >    drivers/pci/controller/dwc/pcie-designware-host.c | 7 +++++++
> > >    drivers/pci/controller/dwc/pcie-designware.h      | 2 ++
> > >    2 files changed, 9 insertions(+)
> > >
> > > diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
> > > index e92513c5bda5..e8b975044b22 100644
> > > --- a/drivers/pci/controller/dwc/pcie-designware-host.c
> > > +++ b/drivers/pci/controller/dwc/pcie-designware-host.c
> > > @@ -619,6 +619,9 @@ int dw_pcie_host_init(struct dw_pcie_rp *pp)
> > >    		}
> > >    	}
> > > +	pp->device_id = 0xffff;
> > > +	of_property_read_u32(np, "device-id", &pp->device_id);
> > > +
> > >    	dw_pcie_version_detect(pci);
> > >    	dw_pcie_iatu_detect(pci);
> > > @@ -1094,6 +1097,10 @@ int dw_pcie_setup_rc(struct dw_pcie_rp *pp)
> > >    	dw_pcie_writel_dbi(pci, PCI_BASE_ADDRESS_0, 0);
> > > +	/* Program correct device id */
> > > +	if (pp->device_id != 0xffff)
> > > +		dw_pcie_writew_dbi(pci, PCI_DEVICE_ID, pp->device_id);
> > > +
> > >    	/* Program correct class for RC */
> > >    	dw_pcie_writew_dbi(pci, PCI_CLASS_DEVICE, PCI_CLASS_BRIDGE_PCI);
> > > diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
> > > index e995f692a1ec..eff6da9438c4 100644
> > > --- a/drivers/pci/controller/dwc/pcie-designware.h
> > > +++ b/drivers/pci/controller/dwc/pcie-designware.h
> > > @@ -431,6 +431,8 @@ struct dw_pcie_rp {
> > >    	struct pci_config_window *cfg;
> > >    	bool			ecam_enabled;
> > >    	bool			native_ecam;
> > > +	u32			vendor_id;
> >
> > I don't see where vendor_id is used.
> > And why should dwc core take care of per HW bugs, could someone else
> > will argue their HW doesn't program correct vender id/class code, then
> > we add more into dw_pcie_rp to fix these?
>
> Device ID and Vendor ID are PCI generic properties and many controllers specify
> them in devicetree due to the default values being wrong or just hardcode them
> in the driver. There is nothing wrong in DWC core programming these values if
> they are available in devicetree.
>
> > How about do it in the defective HW drivers?
>
> If the issue is a vendor DWC wrapper specific, for sure it should be added to
> the relevant controller driver. But this issue is pretty common among the DWC
> wrapper implementations.

I think there are already some dwc instances working around this kind of 
defects in their relevant condroller driver.

drivers/pci/controller/dwc/pci-keystone.c:806:  dw_pcie_writew_dbi(pci, 
PCI_VENDOR_ID, id & PCIE_VENDORID_MASK);

drivers/pci/controller/dwc/pcie-spacemit-k1.c:146: 
dw_pcie_writew_dbi(pci, PCI_VENDOR_ID, PCI_VENDOR_ID_SPACEMIT);

drivers/pci/controller/dwc/pcie-spear13xx.c:139: 
dw_pcie_writew_dbi(pci, PCI_VENDOR_ID, 0x104A);

drivers/pci/controller/dwc/pci-keystone.c:807:  dw_pcie_writew_dbi(pci, 
PCI_DEVICE_ID, id >> PCIE_DEVICEID_SHIFT);

drivers/pci/controller/dwc/pcie-spacemit-k1.c:147: 
dw_pcie_writew_dbi(pci, PCI_DEVICE_ID, PCI_DEVICE_ID_SPACEMIT_K1);

drivers/pci/controller/dwc/pcie-spear13xx.c:140: 
dw_pcie_writew_dbi(pci, PCI_DEVICE_ID, 0xCD80);

If this patch applied, there are two non-consistent apporaches to work
around this situation. Could dwc core provide a common helper for 
them(this qcom instance inclueded) to call without bothering the dwc core?

> - Mani