[PATCH rtw-next] wifi: rtl8xxxu: isolate the USB register buffer

[Kim Wooseok via B4 Relay]

I encountered reconnect failures on four Raspberry Pis in my project.
While investigating the failure on a Raspberry Pi 5 after an AP power
cycle, I found that RF_MODE had been corrupted. Restoring its initialized
value restored reception without reloading the driver.

The USB register buffer shared a cache line with CPU-written mutex state.
This patch allocates the buffer separately while keeping the existing
register access and locking.

I tested the separate-buffer approach on the Pi's Linux 6.18.34 kernel.
During repeated scan requests, wireless ping traffic kept receiving
replies and the RF_MODE and HSSI values stayed stable. I also built the
submission's rtl8xxxu driver for ARM64 with W=1; sparse reported no
diagnostics in core.c.

Signed-off-by: Kim Wooseok <5mghybrid@xxxxxxxxx>

---
Kim Wooseok (1):
      wifi: rtl8xxxu: isolate the USB register buffer from CPU state

 drivers/net/wireless/realtek/rtl8xxxu/core.c     | 35 ++++++++++++++++--------
 drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu.h |  2 +-
 2 files changed, 24 insertions(+), 13 deletions(-)
---
base-commit: 83de3a16c7b37064a59305040ba9b0f93b832794
change-id: 20261010-rtl8xxxu-usb-dma-c94f476e1047

Best regards,
--  
Kim Wooseok <5mghybrid@xxxxxxxxx>