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

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Message-ID: <c43b637a-a0c1-4106-b37b-df389c085057@rock-chips.com>
Date: Sun, 30 Nov 2025 10:43:14 +0800
From: Shawn Lin <shawn.lin@...k-chips.com>
To: Manivannan Sadhasivam <mani@...nel.org>
Cc: shawn.lin@...k-chips.com,
 Sushrut Shree Trivedi <sushrut.trivedi@....qualcomm.com>,
 Jingoo Han <jingoohan1@...il.com>, Lorenzo Pieralisi
 <lpieralisi@...nel.org>, Krzysztof Wilczyński
 <kwilczynski@...nel.org>, Rob Herring <robh@...nel.org>,
 Bjorn Helgaas <bhelgaas@...gle.com>, cros-qcom-dts-watchers@...omium.org,
 Bjorn Andersson <andersson@...nel.org>,
 Konrad Dybcio <konradybcio@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley
 <conor+dt@...nel.org>, linux-pci@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
 devicetree@...r.kernel.org
Subject: Re: [PATCH 1/2] PCI: dwc: Program device-id

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@....qualcomm.com>
>>> ---
>>>    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
>