mirror of
https://github.com/hardkernel/linux.git
synced 2026-04-15 01:50:40 +09:00
dc71e51944
According to the design guide of dwc2, the application must flush all FIFOs after reallocating the FIFO data RAM and the phy is required to keep power on when flush FIFO. But on some rockchip platforms, the usb phy will be powered off when the usb otg/gadget disconnect, in this case if the application call the function dwc2_hsotg_udc_start() to start udc, it will result in the error as below: dwc2_hsotg_init_fifo: timeout flushing fifos (GRSTCTL=80000430) dwc2_core_reset() HANG! Soft Reset GRSTCTL=80000001 bound driver configfs-gadget dwc2_core_reset() HANG! Soft Reset GRSTCTL=80000001 This patch make the dwc2 driver to manage the power of phy in udc start and stop function both in otg and peripheral mode. Make sure that the usb phy is powered on when udc start, and then the usb phy driver can manage the phy power dynamically. Change-Id: I15d3cb5313fc157b58a37c9e15f191d7cb966217 Signed-off-by: Meng Dongyang <daniel.meng@rock-chips.com>
To understand all the Linux-USB framework, you'll use these resources:
* This source code. This is necessarily an evolving work, and
includes kerneldoc that should help you get a current overview.
("make pdfdocs", and then look at "usb.pdf" for host side and
"gadget.pdf" for peripheral side.) Also, Documentation/usb has
more information.
* The USB 2.0 specification (from www.usb.org), with supplements
such as those for USB OTG and the various device classes.
The USB specification has a good overview chapter, and USB
peripherals conform to the widely known "Chapter 9".
* Chip specifications for USB controllers. Examples include
host controllers (on PCs, servers, and more); peripheral
controllers (in devices with Linux firmware, like printers or
cell phones); and hard-wired peripherals like Ethernet adapters.
* Specifications for other protocols implemented by USB peripheral
functions. Some are vendor-specific; others are vendor-neutral
but just standardized outside of the www.usb.org team.
Here is a list of what each subdirectory here is, and what is contained in
them.
core/ - This is for the core USB host code, including the
usbfs files and the hub class driver ("hub_wq").
host/ - This is for USB host controller drivers. This
includes UHCI, OHCI, EHCI, and others that might
be used with more specialized "embedded" systems.
gadget/ - This is for USB peripheral controller drivers and
the various gadget drivers which talk to them.
Individual USB driver directories. A new driver should be added to the
first subdirectory in the list below that it fits into.
image/ - This is for still image drivers, like scanners or
digital cameras.
../input/ - This is for any driver that uses the input subsystem,
like keyboard, mice, touchscreens, tablets, etc.
../media/ - This is for multimedia drivers, like video cameras,
radios, and any other drivers that talk to the v4l
subsystem.
../net/ - This is for network drivers.
serial/ - This is for USB to serial drivers.
storage/ - This is for USB mass-storage drivers.
class/ - This is for all USB device drivers that do not fit
into any of the above categories, and work for a range
of USB Class specified devices.
misc/ - This is for all USB device drivers that do not fit
into any of the above categories.