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author | Terin Stock <terin@terinstock.com> | 2018-09-09 21:24:31 -0700 |
---|---|---|
committer | Felipe Balbi <felipe.balbi@linux.intel.com> | 2018-12-05 11:13:14 +0200 |
commit | 6ed30a7d8ec29d3aba46e47aa8b4a44f077dda4e (patch) | |
tree | 75c572da124c9259ddfd1fbf18d94aacd8480c29 /drivers/usb/dwc2/hcd_queue.c | |
parent | 47b6f8bf870035d420614844de5e308abe505e8a (diff) | |
download | linux-6ed30a7d8ec29d3aba46e47aa8b4a44f077dda4e.tar.gz linux-6ed30a7d8ec29d3aba46e47aa8b4a44f077dda4e.tar.bz2 linux-6ed30a7d8ec29d3aba46e47aa8b4a44f077dda4e.zip |
usb: dwc2: host: use hrtimer for NAK retries
Modify the wait delay utilize the high resolution timer API to allow for
more precisely scheduled callbacks.
A previous commit added a 1ms retry delay after multiple consecutive
NAKed transactions using jiffies. On systems with a low timer interrupt
frequency, this delay may be significantly longer than specified,
resulting in misbehavior with some USB devices.
This scenario was reached on a Raspberry Pi 3B with a Macally FDD-USB
floppy drive (identified as 0424:0fdc Standard Microsystems Corp.
Floppy, based on the USB97CFDC USB FDC). With the relay delay, the drive
would be unable to mount a disk, replying with NAKs until the device was
reset.
Using ktime, the delta between starting the timer (in dwc2_hcd_qh_add)
and the callback function can be determined. With the original delay
implementation, this value was consistently approximately 12ms. (output
in us).
<idle>-0 [000] ..s. 1600.559974: dwc2_wait_timer_fn: wait_timer delta: 11976
<idle>-0 [000] ..s. 1600.571974: dwc2_wait_timer_fn: wait_timer delta: 11977
<idle>-0 [000] ..s. 1600.583974: dwc2_wait_timer_fn: wait_timer delta: 11976
<idle>-0 [000] ..s. 1600.595974: dwc2_wait_timer_fn: wait_timer delta: 11977
After converting the relay delay to using a higher resolution timer, the
delay was much closer to 1ms.
<idle>-0 [000] d.h. 1956.553017: dwc2_wait_timer_fn: wait_timer delta: 1002
<idle>-0 [000] d.h. 1956.554114: dwc2_wait_timer_fn: wait_timer delta: 1002
<idle>-0 [000] d.h. 1957.542660: dwc2_wait_timer_fn: wait_timer delta: 1004
<idle>-0 [000] d.h. 1957.543701: dwc2_wait_timer_fn: wait_timer delta: 1002
The floppy drive operates properly with delays up to approximately 5ms,
and sends NAKs for any delays that are longer.
Fixes: 38d2b5fb75c1 ("usb: dwc2: host: Don't retry NAKed transactions right away")
Cc: <stable@vger.kernel.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Acked-by: Minas Harutyunyan <hminas@synopsys.com>
Signed-off-by: Terin Stock <terin@terinstock.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Diffstat (limited to 'drivers/usb/dwc2/hcd_queue.c')
-rw-r--r-- | drivers/usb/dwc2/hcd_queue.c | 19 |
1 files changed, 12 insertions, 7 deletions
diff --git a/drivers/usb/dwc2/hcd_queue.c b/drivers/usb/dwc2/hcd_queue.c index 40839591d2ec..ea3aa640c15c 100644 --- a/drivers/usb/dwc2/hcd_queue.c +++ b/drivers/usb/dwc2/hcd_queue.c @@ -59,7 +59,7 @@ #define DWC2_UNRESERVE_DELAY (msecs_to_jiffies(5)) /* If we get a NAK, wait this long before retrying */ -#define DWC2_RETRY_WAIT_DELAY (msecs_to_jiffies(1)) +#define DWC2_RETRY_WAIT_DELAY 1*1E6L /** * dwc2_periodic_channel_available() - Checks that a channel is available for a @@ -1464,10 +1464,12 @@ static void dwc2_deschedule_periodic(struct dwc2_hsotg *hsotg, * qh back to the "inactive" list, then queues transactions. * * @t: Pointer to wait_timer in a qh. + * + * Return: HRTIMER_NORESTART to not automatically restart this timer. */ -static void dwc2_wait_timer_fn(struct timer_list *t) +static enum hrtimer_restart dwc2_wait_timer_fn(struct hrtimer *t) { - struct dwc2_qh *qh = from_timer(qh, t, wait_timer); + struct dwc2_qh *qh = container_of(t, struct dwc2_qh, wait_timer); struct dwc2_hsotg *hsotg = qh->hsotg; unsigned long flags; @@ -1491,6 +1493,7 @@ static void dwc2_wait_timer_fn(struct timer_list *t) } spin_unlock_irqrestore(&hsotg->lock, flags); + return HRTIMER_NORESTART; } /** @@ -1521,7 +1524,8 @@ static void dwc2_qh_init(struct dwc2_hsotg *hsotg, struct dwc2_qh *qh, /* Initialize QH */ qh->hsotg = hsotg; timer_setup(&qh->unreserve_timer, dwc2_unreserve_timer_fn, 0); - timer_setup(&qh->wait_timer, dwc2_wait_timer_fn, 0); + hrtimer_init(&qh->wait_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); + qh->wait_timer.function = &dwc2_wait_timer_fn; qh->ep_type = ep_type; qh->ep_is_in = ep_is_in; @@ -1690,7 +1694,7 @@ void dwc2_hcd_qh_free(struct dwc2_hsotg *hsotg, struct dwc2_qh *qh) * won't do anything anyway, but we want it to finish before we free * memory. */ - del_timer_sync(&qh->wait_timer); + hrtimer_cancel(&qh->wait_timer); dwc2_host_put_tt_info(hsotg, qh->dwc_tt); @@ -1716,6 +1720,7 @@ int dwc2_hcd_qh_add(struct dwc2_hsotg *hsotg, struct dwc2_qh *qh) { int status; u32 intr_mask; + ktime_t delay; if (dbg_qh(qh)) dev_vdbg(hsotg->dev, "%s()\n", __func__); @@ -1734,8 +1739,8 @@ int dwc2_hcd_qh_add(struct dwc2_hsotg *hsotg, struct dwc2_qh *qh) list_add_tail(&qh->qh_list_entry, &hsotg->non_periodic_sched_waiting); qh->wait_timer_cancel = false; - mod_timer(&qh->wait_timer, - jiffies + DWC2_RETRY_WAIT_DELAY + 1); + delay = ktime_set(0, DWC2_RETRY_WAIT_DELAY); + hrtimer_start(&qh->wait_timer, delay, HRTIMER_MODE_REL); } else { list_add_tail(&qh->qh_list_entry, &hsotg->non_periodic_sched_inactive); |