Handling short packets (length < max packet size) in the Inventra DMA
engine in the MUSB driver causes the MUSB DMA controller to hang. An
example of a problem that is caused by this problem is when streaming
video out of a UVC gadget, only the first video frame is transferred.

For short packets (mode-0 or mode-1 DMA), MUSB_TXCSR_TXPKTRDY must be
set manually by the driver. This was previously done in musb_g_tx
(musb_gadget.c), but incorrectly (all csr flags were cleared, and only
MUSB_TXCSR_MODE and MUSB_TXCSR_TXPKTRDY were set). Fixing that problem
allows some requests to be transferred correctly, but multiple requests
were often put together in one USB packet, and caused problems if the
packet size was not a multiple of 4. Instead, set MUSB_TXCSR_TXPKTRDY
in dma_controller_irq (musbhsdma.c), just like host mode transfers.

This topic was originally tackled by Nicolas Boichat [0] [1] and is
discussed further at [2] as part of his GSoC project [3].

[0] https://groups.google.com/forum/?hl=en#!topic/beagleboard-gsoc/k8Azwfp75CU
[1] https://gitorious.org/beagleboard-usbsniffer/beagleboard-usbsniffer-kernel/commit/b0be3b6cc195ba732189b04f1d43ec843c3e54c9?p=beagleboard-usbsniffer:beagleboard-usbsniffer-kernel.git;a=patch;h=b0be3b6cc195ba732189b04f1d43ec843c3e54c9
[2] http://beagleboard-usbsniffer.blogspot.com/2010/07/musb-isochronous-transfers-fixed.html
[3] http://elinux.org/BeagleBoard/GSoC/USBSniffer

Fixes: 550a7375fe72 ("USB: Add MUSB and TUSB support")
Signed-off-by: Paul Elder <paul.elder@ideasonboard.com>
Signed-off-by: Bin Liu <b-liu@ti.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Since the runtime PM support was added in musb, dsps relies on the timer
calling otg_timer() to activate the usb subsystem. However the driver
doesn't enable the timer for peripheral port, then the peripheral port is
unable to be enumerated by a host if the other usb port is disabled or in
peripheral mode too.

So let's start the timer for peripheral port too.

Fixes: ea2f35c01d5e ("usb: musb: Fix sleeping function called from invalid context for hdrc glue")
Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Bin Liu <b-liu@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Due to lack of ID pin interrupt event on AM335x devices, the musb dsps
driver uses polling to detect usb device attach for dual-role port.

But in the case if a micro-A cable adapter is attached without a USB device
attached to the cable, the musb state machine gets stuck in a_wait_vrise
state waiting for the MUSB_CONNECT interrupt which won't happen due to the
usb device is not attached. The state is stuck in a_wait_vrise even after
the micro-A cable is detached, which could cause VBUS retention if then the
dual-role port is attached to a host port.

To fix the problem, make a_wait_vrise as a transient state, then move the
state to either a_wait_bcon for host port or a_idle state for dual-role
port, if no usb device is attached to the port.

Signed-off-by: Bin Liu <b-liu@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

TI AM335x CPPI 4.1 module uses a single register bit for CPPI interrupts
in both musb controllers. So disabling the CPPI irq in one musb driver
breaks the other musb module.

Since musb is already disabled before tearing down dma controller in
musb_remove(), it is safe to not disable CPPI irq in
musb_dma_controller_destroy().

Fixes: 255348289f71 ("usb: musb: dsps: Manage CPPI 4.1 DMA interrupt in DSPS")
Cc: stable@vger.kernel.org
Signed-off-by: Bin Liu <b-liu@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

In preparation to enabling -Wimplicit-fallthrough, mark switch cases
where we are expecting to fall through.

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

When calling debugfs functions, there is no need to ever check the
return value.  The function can work or not, but the code logic should
never do something different based on this.

Because of this, lots of init functions do not need to have return
values, so this cleans up a lot of unused error handling code that never
could have triggered in the past.

Cc: Bin Liu <b-liu@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

After the only users of this variable got removed, we now get a
warning about 'otg' being unused:

drivers/usb/musb/da8xx.c: In function 'da8xx_musb_interrupt':
drivers/usb/musb/da8xx.c:226:19: error: unused variable 'otg' [-Werror=unused-variable]

Fixes: d2852f2d3e6d ("usb: musb: remove references to default_a of struct usb_otg")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

UDC core ensures the usb_ep parameter passed in is not NULL, so
checking if (ep != NULL) is pointless.

Convert to_musb_ep() to a simple macro to not directly return NULL to
avoid warnings from code static analysis tools.

Signed-off-by: Bin Liu <b-liu@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

The gadget function drivers should ensure the usb_request parameter
passed in is not NULL. UDC core doesn't check if it is NULL, so MUSB
driver shouldn't have to check it either.

Convert to_musb_request() to a simple macro to not directly return NULL
to avoid warnings from code static analysis tools.

Signed-off-by: Bin Liu <b-liu@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

To be able to use DSPS-based controllers with device-tree descriptions
of the USB topology, we need to associate the glue device's device-tree
node with the child controller device.

Note that this can also be used to eventually let USB core manage
generic phys.

Also note that the other glue drivers will require similar changes to be
able to describe their buses in DT.

Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Bin Liu <b-liu@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>