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eae6460f61
CDNSP controller may lose its runtime register programming across S3
suspend/resume, depending on SoC power domain configuration. After
resume the operational and interrupter registers may contain reset
values, which prevents the gadget side from recovering correctly and
breaks wakeup from S3.
Fix this by detecting whether the controller lost its register context
after resume and handling both cases:
- If context was lost (CFG_3XPORT_U1_PIPE_CLK_GATE_EN set or power
lost): reset the controller and reprogram the state required for
normal operation, including the command ring, DCBAA pointer, doorbell
base, event ring, ERST base/size and event ring dequeue pointer.
- If context was retained: restart the controller directly without
reprogramming registers. Issue a wakeup if the link was in U3 before
suspend.
Move the basic controller register programming out of the one-time memory
initialization path and make it reusable from the resume path. Also
separate ring allocation from ring initialization so that rings can be
reinitialized without reallocating DMA memory.
Always perform the full suspend sequence regardless of the current link
state. Previously, if the device was already in U3, the suspend callback
returned early without stopping the controller, which could lead to
commands being issued on a disabled slot during resume.
Fixes: 3d82904559 ("usb: cdnsp: cdns3 Add main part of Cadence USBSSP DRD Driver")
Cc: stable <stable@kernel.org>
Signed-off-by: Pawel Laszczak <pawell@cadence.com>
Acked-by: Peter Chen <peter.chen@kernel.org>
Link: https://patch.msgid.link/20260820-suspend_resume_fix-v3-1-5a713098b977@cadence.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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