Received-SPF: pass (google.com: domain of linux-wireless-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
MIME-Version: 1.0
From:   Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Date:   Tue, 16 May 2023 18:39:31 +0200
Message-ID: <CAFBinCD=HVyedXpqRfAC=m3A=wstDbtQfLDZqjHufSawdLKwiw@mail.gmail.com>
Subject: wifi: rtw88: questions about adding support for RTL8723DS/RTL8723BS
To:     Ping-Ke Shih <pkshih@realtek.com>, linux-wireless@vger.kernel.org
Cc:     Larry Finger <Larry.Finger@lwfinger.net>, tony0620emma@gmail.com,
        jernej.skrabec@gmail.com
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

Hello Ping-Ke,

as a next step I want to add support for RTW_WCPU_11N SDIO cards to
the rtw88 driver.
Currently only one RTW_WCPU_11N chip is supported: RTL8723D by the
rtw88 (PCIe and USB HCIs).

My first question is very hopefully a simple one:
It seems that RTL8723DS has two SDIO IDs: 0xd723 and 0xd724.
Do these have the same name or is there some kind of "revision" (like
rev 2, revision B, ...) internally?

My second question is more abstract:
Based on my understanding of the vendor drivers for RTL8723BS and
RTL8723DS both seem very close in terms of registers. initialization
sequence, ...
So I am hoping that it's possible to add RTL8723BS support to the rtw88 driver.
There's two main differences that I found so far:
- rtw_dump_hw_feature() doesn't work because REG_C2HEVT has an
incorrect value (C2H_HW_FEATURE_REPORT is expected but it still
contains C2H_HW_FEATURE_DUMP). It seems that this is a firmware issue.
- The whole ltecoex support (my understanding is: this is part of the
Bluetooth 4.2 spec but RTL8723BS was originally developed for the
Bluetooth 4.0 spec) seems missing in terms of all required registers.
I'm not sure if this is a hardware or firmware topic.

Have you considered adding RTW8723B support to the rtw88 driver?
Do you have some initial suggestions on what would be needed to do so
(is my list from above complete, what do do about these points, ...)?

There's a huge number of boards with RTL8723BS out there and I think
they could benefit from the rtw88 driver (and so we can finally get
rid of drivers/staging/rtl8723bs/).


Best regards,
Martin