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SubjectRe: Infinite looping in omap2430.c USB driver
Hi,

On Mon, Aug 13, 2012 at 12:34:53PM +1000, NeilBrown wrote:
> On Thu, 9 Aug 2012 14:15:51 +0300 Felipe Balbi <balbi@ti.com> wrote:
>
>
> > hehe, that's nasty. Please send a patch converting to a try count and a
> > udelay_range(), or something.
> >
>
> how's this?
>
> Thanks,
> NeilBrown
>
>
> From: NeilBrown <neilb@suse.de>
> Date: Mon, 13 Aug 2012 12:32:58 +1000
> Subject: [PATCH] omap2430: don't loop indefinitely in interrupt.
>
> When called during resume_irqs, omap2430_musb_set_vbus() is run with
> interrupts disabled, In that case 'jiffies' never changes so the loop
> can loop forever.
>
> So impose a maximum loop count and add an 'mdelay' to ensure we wait
> a reasonable amount of time for bit to be cleared.
>
> This fixes a hang on resume.
>
> Signed-of-by: NeilBrown <neilb@suse.de>
>
> diff --git a/drivers/usb/musb/omap2430.c b/drivers/usb/musb/omap2430.c
> index c7785e8..8a93381 100644
> --- a/drivers/usb/musb/omap2430.c
> +++ b/drivers/usb/musb/omap2430.c
> @@ -34,6 +34,7 @@
> #include <linux/dma-mapping.h>
> #include <linux/pm_runtime.h>
> #include <linux/err.h>
> +#include <linux/delay.h>
>
> #include "musb_core.h"
> #include "omap2430.h"
> @@ -145,6 +146,7 @@ static void omap2430_musb_set_vbus(struct musb *musb, int is_on)
>
> if (is_on) {
> if (musb->xceiv->state == OTG_STATE_A_IDLE) {
> + int loops = 100;
> /* start the session */
> devctl |= MUSB_DEVCTL_SESSION;
> musb_writeb(musb->mregs, MUSB_DEVCTL, devctl);
> @@ -154,9 +156,11 @@ static void omap2430_musb_set_vbus(struct musb *musb, int is_on)
> */
> while (musb_readb(musb->mregs, MUSB_DEVCTL) & 0x80) {
>
> + mdelay(5);

I would prefer udelay_range() as it will let scheduler group timers.
Something like:

udelay_range(3000, 5000);

should do, I gues...

--
balbi
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