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SubjectRe: [PATCH v7 07/10] usb: dbc: handle endpoint stall
On 26.01.2016 14:58, Lu Baolu wrote:
> In case of endpoint stall, software is able to detect the situation
> by reading DCCTRL.HIT or DCCTRL.HOT bits. DbC follows the normal USB
> framework to handle endpoint stall. When software detects endpoint
> stall situation, it should wait until endpoint is recovered before
> read or write oprations.
>
> Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
> ---
> drivers/usb/early/xhci-dbc.c | 36 ++++++++++++++++++++++++++++++++++++
> 1 file changed, 36 insertions(+)
>
> diff --git a/drivers/usb/early/xhci-dbc.c b/drivers/usb/early/xhci-dbc.c
> index c81df40..344d93e 100644
> --- a/drivers/usb/early/xhci-dbc.c
> +++ b/drivers/usb/early/xhci-dbc.c
> @@ -1163,6 +1163,37 @@ static int xdbc_wait_until_dbc_configured(void)
> return -ETIMEDOUT;
> }
>
> +static int xdbc_wait_until_epstall_cleared(bool read)
> +{
> + int timeout = 0;
> +
> + if (read) {
> + do {
> + if (!(readl(&xdbcp->xdbc_reg->control) & CTRL_HIT)) {
> + xdbcp->in_ep_state = EP_RUNNING;
> +
> + return 0;
> + }
> +
> + xdbcp->in_ep_state = EP_HALTED;
> + xdbc_udelay(10);
> + } while (timeout++ < XDBC_LOOPS);
> + } else {
> + do {
> + if (!(readl(&xdbcp->xdbc_reg->control) & CTRL_HOT)) {
> + xdbcp->out_ep_state = EP_RUNNING;
> +
> + return 0;
> + }
> +
> + xdbcp->out_ep_state = EP_HALTED;
> + xdbc_udelay(10);
> + } while (timeout++ < XDBC_LOOPS);
> + }
> +
> + return -ETIMEDOUT;
> +}
>

how about something like:

enum xdbc_ep_state *ep_state;
u32 halt_bit;

if (read) {
ep_state = &xdbcp->in_ep_state
halt_bit = CTRL_HIT
} else {
ep_state = &xdbcp->out_ep_state
halt_bit = CTRL_HOT
}
do {
if (!(readl(..) & halt_bit)) {
*ep_state = EP_RUNNING;
return 0;
}
*ep_state = EP_HALTED;
delay()
} while (..)


+
> static int xdbc_bulk_transfer(void *data, int size, int loops, bool read)
> {
> u64 addr;
> @@ -1182,6 +1213,11 @@ static int xdbc_bulk_transfer(void *data, int size, int loops, bool read)
> return -EPERM;
> }
>
> + if (xdbc_wait_until_epstall_cleared(read)) {
> + xdbc_trace("%s: endpoint not ready\n", __func__);
> + return -EPERM;

Is -EPERM appropriate here?
Not sure about what error codes the device side is using, but usually HALT is set due to some
Data buffer/transmission/TRB error.
In this case the failure is that debug host failed to send a clearFeature(EP_HALT) request in time.

-Mathias

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