wifi: ath12k: restore register window after global reset

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[ Upstream commit a41281f651 ]

Hardware target implements an address space larger than that PCI BAR can
map. In order to be able to access the whole target address space, the
BAR space is split into 4 segments, of which the last 3, called windows,
can be dynamically mapped to the desired area. This is achieved by
updating WINDOW_REG_ADDRESS register with appropriate window value.
Currently each time when accessing a register that beyond WINDOW_START,
host calculates the window value and caches it after window update,
this way next time when accessing a register falling in the same window,
host knows that the window is already good hence no additional update
needed.

However this mechanism breaks after global reset is triggered in
ath12k_pci_soc_global_reset(), because with global reset hardware resets
WINDOW_REG_ADDRESS register hence the window is not properly mapped any
more. Current host does nothing about this, as a result a subsequent
register access may not work as expected if it falls in a window same as
before.

Although there is no obvious issue seen now, better to fix it to avoid
future problem. The fix is done by restoring the window register after
global reset.

Tested-on: WCN7850 hw2.0 PCI WLAN.HMT.1.1.c5-00284.1-QCAHMTSWPL_V1.0_V2.0_SILICONZ-3

Fixes: d889913205 ("wifi: ath12k: driver for Qualcomm Wi-Fi 7 devices")
Signed-off-by: Baochen Qiang <baochen.qiang@oss.qualcomm.com>
Reviewed-by: Vasanthakumar Thiagarajan <vasanthakumar.thiagarajan@oss.qualcomm.com>
Link: https://patch.msgid.link/20251017-ath12k-reset-window-cache-v1-1-29e0e751deed@oss.qualcomm.com
Signed-off-by: Jeff Johnson <jeff.johnson@oss.qualcomm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

...

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Baochen Qiang 2025-10-17 10:36:36 +08:00 • committed by Greg Kroah-Hartman

parent 04d808a6ef

commit d0a5b5d564

1 changed files with 19 additions and 1 deletions

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drivers/net/wireless/ath/ath12k/pci.c

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