From: "Michael Büsch" <m@bues.ch>
To: "Rafał Miłecki" <zajec5@gmail.com>
Cc: Thommy Jakobsson <thommyj@gmail.com>,
linville@tuxdriver.com, linux-wireless@vger.kernel.org,
b43-dev@lists.infradead.org, piotras@gmail.com,
Larry.Finger@lwfinger.net
Subject: Re: [PATCH] B43: Handle DMA RX descriptor underrun
Date: Sun, 5 May 2013 15:56:19 +0200 [thread overview]
Message-ID: <20130505155619.1f316a6b@milhouse> (raw)
In-Reply-To: <CACna6rxWPOqQPNUaASaj=v=O+Wjt0okjX4jNwE3tv-=etfATCg@mail.gmail.com>
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On Sun, 5 May 2013 14:44:14 +0200
Rafał Miłecki <zajec5@gmail.com> wrote:
> 2013/4/23 Thommy Jakobsson <thommyj@gmail.com>:
> > Add handling of rx descriptor underflow. This fixes a fault that could
> > happen on slow machines, where data is received faster than the CPU can
> > handle. In such a case the device will use up all rx descriptors and
> > refuse to send any more data before confirming that it is ok. This
> > patch enables necessary interrupt to discover such a situation and will
> > handle them by dropping everything in the ring buffer.
>
> Thommy: does it mean firmware actually ignores what we write to the
> B43_DMA64_RXINDEX (recently renamed to the B43_DMA64_RXSTOPINDEX)? Is
> our set_current_rxslot and op64_set_current_rxslot (same for 32bit
> version) useless in this situation?
>
> Could this be a off-by-one issue? Maybe we're writing a value too low
> by a one and firmware believes the whole ring is empty while it's
> full?
The ring looks the same if it's full or empty. We can only know that it is
full when this interrupt fires, which happens as the indexes collide.
--
Michael
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next prev parent reply other threads:[~2013-05-05 13:56 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-04-23 19:45 [PATCH] B43: Handle DMA RX descriptor underrun Thommy Jakobsson
2013-04-23 20:33 ` [PATCH] b43: rename stop-index DMA op Michael Büsch
2013-04-24 7:00 ` [PATCH] B43: Handle DMA RX descriptor underrun Rafał Miłecki
2013-05-03 17:35 ` John W. Linville
2013-05-03 19:40 ` Thommy Jakobsson
2013-05-02 13:06 ` Michael Büsch
2013-05-02 15:01 ` Larry Finger
2013-05-05 12:44 ` Rafał Miłecki
2013-05-05 13:56 ` Michael Büsch [this message]
2013-05-05 15:34 ` Rafał Miłecki
2013-05-05 19:09 ` Thommy Jakobsson
2013-05-05 15:43 ` Rafał Miłecki
2013-05-05 16:31 ` Rafał Miłecki
2013-05-05 17:24 ` Michael Büsch
2013-05-05 19:50 ` Rafał Miłecki
2013-05-05 19:58 ` Michael Büsch
2013-05-05 20:06 ` Thommy Jakobsson
2013-05-05 19:59 ` Thommy Jakobsson
2013-05-05 19:22 ` Larry Finger
2013-05-13 18:27 ` Thommy Jakobsson
2013-05-24 16:49 ` John W. Linville
2013-05-25 19:02 ` Thommy Jakobsson
2013-05-25 19:37 ` Hauke Mehrtens
2013-05-25 19:42 ` Michael Büsch
2013-05-25 20:37 ` Larry Finger
2013-05-28 17:37 ` John W. Linville
2013-06-10 9:40 ` Rafał Miłecki
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