Re: [PATCH] usb: ehci: Quiesce ASPEED EHCI before halting it on shutdown

[sashiko-bot@kernel.org]

> On ASPEED EHCI controllers, clearing USBCMD.RS while both the periodic
> and asynchronous schedules are enabled may leave the controller unable
> to halt. If an asynchronous transaction is in progress when RS is
> cleared, it may run past the end of the micro-frame. The controller then
> clears its internal schedule buffer at the start of the next micro-frame
> while it is already walking the periodic schedule, issues a DMA read
> from address 0x0 and never sets USBSTS.HCHalted.
> 
> ehci_shutdown() calls ehci_silence_controller(), which halts the
> controller without first turning off the schedules. For ASPEED
> controllers, call ehci_quiesce() first to clear CMD_ASE/CMD_PSE and
> wait for STS_ASS/STS_PSS to clear, as ehci_stop() and
> ehci_bus_suspend() already do before halting. This is also the stop
> sequence recommended by ASPEED.
> 
> [ ... ]
> state writes the command register with these bits still cleared
> and polls the schedule status bits using the existing timeout
> limits, without re-enabling the controller or its schedules.
> 
> Signed-off-by: Joe Wang <joe_wang@aspeedtech.com>

Sashiko has reviewed this patch and found no issues. It looks great!

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Sashiko AI review · https://sashiko.dev/#/patchset/20261016-upstream_ehci_aspeed_shutdown-v1-1-8440c13b5652@aspeedtech.com?part=1