RE: [PATCH v3] usb: cdnsp: Add support for device-only configuration

[Pawel Laszczak]

>
>On Fri, May 08, 2026 at 12:06:39PM +0200, Pawel Laszczak via B4 Relay wrote:
>> From: Pawel Laszczak <pawell@xxxxxxxxxxx>
>>
>> This patch introduces support for the Cadence USBSSP (cdnsp)
>> controller in hardware configurations where the Dual-Role Device (DRD)
>> register block is not implemented or is inaccessible.
>>
>> In such cases, the driver cannot rely on the DRD logic to manage roles
>> and must operate exclusively in a fixed peripheral/host mode.
>>
>> The change in BAR indexing (from BAR 2 to BAR 1) is a direct
>> consequence of the 32-bit addressing used in this specific
>> DRD-disabled hardware layout, compared to the 64-bit addressing
>> used in DRD-enabled configurations.
>>
>> Tested on a PCI platform with a hardware configuration that lacks
>> DRD support. Platform-side changes are included to support the PCI
>> glue layer's property injection to handle this specific layout.
>>
>> Acked-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx> # pci_ids.h
>
>I did ack this
>(https://urldefense.com/v3/__https://lore.kernel.org/linux-
>pci/20260331181209.GA148250@bhelgaas/__;!!EHscmS1ygiU1lA!FuLlHX77O5
>UQAo4VHUkfgZidHZN93lMxhVIR_vVAG4bwI0IoUUHK7pB-CiNE7-
>PxraJZow0ZH7Q5BGk$ ) but I
>wish I had added a note about why.  Usually we don't add things to
>pci_ids.h unless they're used by more than one driver.  This (slightly)
>simplifies backporting things.
>
>Fine as-is, but if you respin for other reasons, you could consider moving
>it to cdnsp-pci.c.
>
>> +++ b/include/linux/pci_ids.h
>
> *      Do not add new entries to this file unless the definitions
> *      are shared between multiple drivers.
> */
>
>> +#define PCI_DEVICE_ID_CDNS_UDC_USBSSP	0x0400
>
>Looks like this #define could go in cdnsp-pci.c, since that's the only
>place it's used.

Hi Bjorn,
thank you for the feedback. I'll move the PCI_DEVICE_ID_CDNS_UDC_USBSSP
definition to cdnsp-pci.c in the next version (v4) to keep pci_ids.h clean.

Best regards,
Pawel