Hi,
On Wed, Apr 27, 2016 at 09:51:58AM +0300, Max Uvarov wrote:
> Fix soft lockup when resetting remote device attached
> to usb host. Configuration:
> pppd -> musb hub -> usb-serial -> gsm modem
I have heard a few reports similar to this symptom, but never been able
to reproduce it on my side.
> When gsm modem resets, musb rolls in incoming rx interrupts
> which does not give any time to other application as result
> it totally lock ups. Solution is to keep original logic for RXCSR_H_ERROR
Have you looked where exact place in the interrupt routine the execution
has stuck in?
> and merge RXCSR_DATAERROR and RXCSR_H_ERROR branches to call same code
> for setting rx stall with MUSB_RXCSR_H_WZC_BITS.
MUSB_RXCSR_H_WZC_BITS itself does not set rx stall, it just ensures
MUSB_RXCSR_H_RXSTALL not to be cleared. Please check its comment in
musb_regs.h.
>
> Signed-off-by: Max Uvarov <muvarov@xxxxxxxxx>
> ---
> v2: use bitwise or for error flags before logical and. (Sergei Shtylyov).
>
> drivers/usb/musb/musb_host.c | 12 +++++-------
> 1 file changed, 5 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/usb/musb/musb_host.c b/drivers/usb/musb/musb_host.c
> index c3d5fc9..2d9aa78 100644
> --- a/drivers/usb/musb/musb_host.c
> +++ b/drivers/usb/musb/musb_host.c
> @@ -1592,14 +1592,12 @@ void musb_host_rx(struct musb *musb, u8 epnum)
What kernel do you use? This line # is away off from upstream kernel.
>
> /* stall; record URB status */
> status = -EPIPE;
> + } else if (rx_csr & (MUSB_RXCSR_DATAERROR | MUSB_RXCSR_H_ERROR)) {
>
> - } else if (rx_csr & MUSB_RXCSR_H_ERROR) {
> - dev_dbg(musb->controller, "end %d RX proto error\n", epnum);
> -
> - status = -EPROTO;
> - musb_writeb(epio, MUSB_RXINTERVAL, 0);
> -
> - } else if (rx_csr & MUSB_RXCSR_DATAERROR) {
> + if (rx_csr & MUSB_RXCSR_H_ERROR) {
> + status = -EPROTO;
> + musb_writeb(epio, MUSB_RXINTERVAL, 0);
> + }
Please help me to understand how this change fixes the issue. I see the
most effect of the change here is directly 'goto finish' so that 'done'
flag is not set, then musb_advance_schedule() is not called. Is this the
case or I missed other important pieces?
Thanks,
-Bin.
>
> if (USB_ENDPOINT_XFER_ISOC != qh->type) {
> dev_dbg(musb->controller, "RX end %d NAK timeout\n", epnum);
> --
> 1.9.1
>
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