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70a7f8be85
This patch adds support for USB suspend to the Atmel UDC. When suspended, the UDC clock can be stopped, resulting in some power savings. The "wake up" interrupt will fire irregardless of whether the clock is running or not, allowing the UDC clock to be restarted when the USB master wants to wake the device again. The IRQ state of this device is somewhat fiddly. The "wake up" IRQ seems to actually be a "bus activity" indicator; the IRQ is almost continuously asserted so enabling this IRQ should only be done after a suspend when the wake IRQ becomes relevant. Similarly, the "suspend" IRQ detects "bus inactivity" and may therefore fire together with a "wake" if the two types of activity coincide during the period between two IRQ handler invocations; therefore, it's important to ignore the "suspend" IRQ while waiting for a wake-up. This has been tested on a SAMA5D2 board. Signed-off-by: Jonas Bonn <jonas@norrbonn.se> CC: Cristian Birsan <cristian.birsan@microchip.com> CC: Felipe Balbi <balbi@kernel.org> CC: Greg Kroah-Hartman <gregkh@linuxfoundation.org> CC: Nicolas Ferre <nicolas.ferre@microchip.com> CC: Alexandre Belloni <alexandre.belloni@bootlin.com> CC: Ludovic Desroches <ludovic.desroches@microchip.com> CC: linux-arm-kernel@lists.infradead.org CC: linux-usb@vger.kernel.org Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.