From: Jeaho Hwang <jhhwang@rtst.co.kr>
To: Peter Chen <peter.chen@kernel.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: tglx@linutronix.de, linux-rt-users@vger.kernel.org,
team-linux@rtst.co.kr, mkbyeon@lselectric.co.kr,
khchoib@lselectric.co.kr
Subject: [PATCH v2] usb: chipidea: local_irq_save/restore added for hw_ep_prime
Date: Tue, 17 Aug 2021 18:53:13 +0900 [thread overview]
Message-ID: <20210817095313.GA671484@ubuntu> (raw)
hw_ep_prime sometimes fails if irq occurs while it rus on RT kernel.
local_irq_save/restore is added inside the function to gurantee atomicity.
only effective for preempt_rt since hw_ep_prime is called inside top half
or spin_lock_irqsave. No effect is expected for standard linux.
Signed-off-by: Jeaho Hwang <jhhwang@rtst.co.kr>
diff --git a/drivers/usb/chipidea/udc.c b/drivers/usb/chipidea/udc.c
index 8834ca613721..a624eddb3e22 100644
--- a/drivers/usb/chipidea/udc.c
+++ b/drivers/usb/chipidea/udc.c
@@ -191,22 +191,31 @@ static int hw_ep_get_halt(struct ci_hdrc *ci, int num, int dir)
static int hw_ep_prime(struct ci_hdrc *ci, int num, int dir, int is_ctrl)
{
int n = hw_ep_bit(num, dir);
+ unsigned long flags;
+ int ret = 0;
/* Synchronize before ep prime */
wmb();
- if (is_ctrl && dir == RX && hw_read(ci, OP_ENDPTSETUPSTAT, BIT(num)))
+ /* irq affects this routine so irq should be disabled on RT.
+ * on standard kernel, irq is already disabled by callers.
+ */
+ local_irq_save(flags);
+ if (is_ctrl && dir == RX && hw_read(ci, OP_ENDPTSETUPSTAT, BIT(num))) {
+ local_irq_restore(flags);
return -EAGAIN;
+ }
hw_write(ci, OP_ENDPTPRIME, ~0, BIT(n));
while (hw_read(ci, OP_ENDPTPRIME, BIT(n)))
cpu_relax();
if (is_ctrl && dir == RX && hw_read(ci, OP_ENDPTSETUPSTAT, BIT(num)))
- return -EAGAIN;
+ ret = -EAGAIN;
+ local_irq_restore(flags);
/* status shoult be tested according with manual but it doesn't work */
- return 0;
+ return ret;
}
/**
--
2.25.1
next reply other threads:[~2021-08-17 9:54 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-17 9:53 Jeaho Hwang [this message]
2021-08-18 16:17 ` [PATCH v2] usb: chipidea: local_irq_save/restore added for hw_ep_prime Sebastian Andrzej Siewior
2021-08-18 23:50 ` Jeaho Hwang
2021-08-19 8:47 ` Sebastian Andrzej Siewior
2021-08-20 5:15 ` Jeaho Hwang
2021-08-21 5:05 ` Peter Chen
2021-08-21 7:04 ` Jeaho Hwang
2021-08-23 16:14 ` Sebastian Andrzej Siewior
2021-08-23 16:51 ` Sebastian Andrzej Siewior
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