From: anarsoul@gmail•com (Vasily Khoruzhick)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH] s3c2410_udc: Add handling for S3C244X dual-packet mode
Date: Mon, 6 Sep 2010 13:29:36 +0300 [thread overview]
Message-ID: <201009061329.45290.anarsoul@gmail.com> (raw)
In-Reply-To: <1283178862-12987-1-git-send-email-anarsoul@gmail.com>
? ????????? ?? 30 ??????? 2010 17:34:22 ????? Vasily Khoruzhick ???????:
> From: Fabian Godehardt <fg@emlix•com>
>
> This is a patch that seems to make the USB hangs on the S3C244X go away.
> At least a good amount of ping torture didn't make them come back so far.
>
> The issue is that, if there are several back-to-back packets, sometimes no
> interrupt is generated for one of them. This seems to be caused by the
> mysterious dual packet mode, which the USB hardware enters automatically
> if the endpoint size is half that of the FIFO. (On the 244X, this is the
> normal situation for bulk data endpoints.)
>
> There is also a timing factor in this. It seems that what happens is that
> the USB hardware automatically sends an acknowledgement if there is only
> one packet in the FIFO (the FIFO has space for two). If another packet
> arrives before the host has retrieved and acknowledged the previous one,
> no interrupt is generated for that second one.
>
> However, there may be an indication. There is one undocumented bit (none
> of the 244x manuals document it), OUT_CRS1_REG[1], that seems to be set
> suspiciously often when this condition occurs. There is also
> CLR_DATA_TOGGLE, OUT_CRS1_REG[7], which may have a function related to
> this. (The Samsung manual is rather terse on that, as usual.)
>
> This needs to be examined further. For now, the patch seems to do the
> trick.
Ping
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next prev parent reply other threads:[~2010-09-06 10:29 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-08-30 14:34 [PATCH] s3c2410_udc: Add handling for S3C244X dual-packet mode Vasily Khoruzhick
2010-09-06 10:29 ` Vasily Khoruzhick [this message]
2010-12-06 19:39 ` Vasily Khoruzhick
2010-12-08 0:52 ` Ben Dooks
2010-12-13 10:37 ` Vasily Khoruzhick
2011-01-12 10:04 ` Vasily Khoruzhick
2011-02-07 2:07 ` Lars-Peter Clausen
2011-02-07 2:32 ` Greg KH
2011-02-07 10:53 ` [PATCH RESEND] " Vasily Khoruzhick
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