RE: [PATCH] wifi: rtw88: 8821c: Add HP single-antenna quirk

[Ping-Ke Shih <pkshih@realtek.com>]

Paolo Lazzaroni <eexto@aol.com> wrote:
> > If this is the only one platform which needs this kind of quirk. Add an entry
> > to rtw_pci_quirks[].
> 
> Regarding rtw_pci_quirks[]:
> 
> The reason I matched the PCI subsystem ID (10ec:c821 [103c:831a]) rather
> than DMI in rtw_pci_quirks[] is that HP assigns this specific subsystem
> ID across a family of laptop platforms (e.g. HP 15-da, 15-db, and related
> chassis) to denote the single physical antenna connected to Aux/S1.
> This is documented in the OEM Windows driver INF (netrtwlane.inf):
>   "PCI\VEN_10EC&DEV_C821&SUBSYS_831A103C ;;single ant(connect to right one S1)"
> 
> If we use DMI matching in rtw_pci_quirks[], it would only match this specific
> laptop SKU ("HP Laptop 15-da0xxx" / "4XW76EA#ABZ"), leaving other HP models
> sharing this identical 103c:831a single-antenna card with severe signal loss.
> 
> However, I understand that inspecting PCI structures inside rtw8821c_read_efuse()
> violates bus abstraction for rtw8821c.c.
> 
> Would you prefer:
> Option A: Keep the PCI subsystem match, but handle it cleanly in rtw_pci_probe()
>           (e.g., setting a flag or rfe_option override in rtwdev before chip setup)?
> Option B: Add a DMI entry to rtw_pci_quirks[] matching this platform?

I prefer option A, but yes, please handle it cleanly in pci.c. 
You can flag a quirk at pci.c, and update rfe_option in 8821c.c.

Ping-Ke