Re: [PATCH v3] USB: hub: call ACPI _PRR reset during port power-cycle on enumeration failure

[sashiko-bot@kernel.org]

> Some USB-connected devices (e.g. MT7925 Bluetooth on Dell laptops) expose
> their hardware reset line via an ACPI Power Resource for Reset (_PRR)
> rather than relying solely on VBUS cycling for recovery.  When the reset
> GPIO gets stuck low the device stops responding on USB; a VBUS power-cycle
> alone cannot recover it because the chip remains in reset regardless of
> VBUS state.
> 
> Add usb_acpi_port_prr_reset() in usb-acpi.c that, given a hub device and
> one-based port number, looks up the port's ACPI companion handle, evaluates
> _PRR to obtain the power-resource reference, and then calls _RST on that
> reference to toggle the reset line.  The function is a no-op if the port
> has no ACPI handle or no _PRR method, so it is safe to call unconditionally
> for every port.
> 
> Wire it into hub_port_connect() during the mid-retry VBUS power-cycle
> [ ... ]
> 
> Signed-off-by: Chia-Lin Kao (AceLan) <acelan.kao@canonical.com>
> Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org>
> Link: https://patch.msgid.link/20260706080117.3754550-1-acelan.kao@canonical.com
> Signed-off-by: Mario Limonciello (AMD) <superm1@kernel.org>

Sashiko has reviewed this patch and found no issues.

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