usb: dwc3: core: add support for disabling High-speed park mode
Setting the PARKMODE_DISABLE_HS bit in the DWC3_USB3_GUCTL1.
When this bit is set to '1' all HS bus instances in park mode are disabled
For some USB wifi devices, if enable this feature it will reduce the
performance. Therefore, add an option for disabling HS park mode by
device-tree.
In Synopsys's dwc3 data book:
In a few high speed devices when an IN request is sent within 900ns of the
ACK of the previous packet, these devices send a NAK. When connected to
these devices, if required, the software can disable the park mode if you
see performance drop in your system. When park mode is disabled,
pipelining of multiple packet is disabled and instead one packet at a time
is requested by the scheduler. This allows up to 12 NAKs in a micro-frame
and improves performance of these slow devices.
Acked-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
Signed-off-by: Stanley Chang <stanley_chang@realtek.com>
Link: https://lore.kernel.org/r/20230419020044.15475-1-stanley_chang@realtek.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>