From: Bitterblue Smith <rtl8821cerfe2@gmail.com>
To: "linux-wireless@vger.kernel.org" <linux-wireless@vger.kernel.org>
Cc: Ping-Ke Shih <pkshih@realtek.com>
Subject: rtw88: The debugfs interface reads registers from the wrong device
Date: Mon, 15 Jul 2024 14:05:03 +0300 [thread overview]
Message-ID: <e28bbf72-678a-438b-b5dc-d4ae8b8f71f0@gmail.com> (raw)
Hi,
To reproduce the problem, you need a computer with two wifi
devices supported by rtw88. It's especially easy to notice
the problem if one of the devices is USB and the other is PCI,
because the PCI device will have various values in the
registers 0x300..0x3ff, but the USB device will have all
0xeaeaeaea there.
1. Let's assume the driver for the PCI device is already loaded.
I have RTL8822CE.
2. Mount debugfs:
# mount -t debugfs none /sys/kernel/debug
3. Check page 0x300:
# cat /sys/kernel/debug/ieee80211/phy0/rtw88/mac_3
00000300 f7138000 33330000 ffffb000 00000000
.....
4. Plug the USB device. I used RTL8811CU.
5. Check page 0x300 again:
# cat /sys/kernel/debug/ieee80211/phy0/rtw88/mac_3
00000300 eaeaeaea eaeaeaea eaeaeaea eaeaeaea
.....
6. Bonus: unload rtw88_8821cu and check page 0x300 again to get
a null pointer dereference:
# rmmod rtw88_8821cu
# cat /sys/kernel/debug/ieee80211/phy0/rtw88/mac_3
next reply other threads:[~2024-07-15 11:05 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-07-15 11:05 Bitterblue Smith [this message]
2024-07-15 11:26 ` rtw88: The debugfs interface reads registers from the wrong device Bitterblue Smith
2024-07-16 1:19 ` Ping-Ke Shih
2024-07-16 2:56 ` Ping-Ke Shih
2024-07-18 6:45 ` Ping-Ke Shih
2024-07-30 16:27 ` Kalle Valo
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