From: javi.merino@arm•com (Javi Merino)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH v2] ARM: pl330: Fix a race condition
Date: Mon, 28 Nov 2011 16:36:46 +0000 [thread overview]
Message-ID: <4ED3B89E.7070903@arm.com> (raw)
In-Reply-To: <000c01ccada6$f83f5be0$e8be13a0$%kim@samsung.com>
On 28/11/11 08:23, Boojin Kim wrote:
> Javi Merino wrote:
>
>>> On Samsung's Exynos4 platform, while testing audio playback with i2s
>>> interface, the above change causes the playback to freeze. The
>>> _thrd_active(thrd) call always returns '1' and hence _start(thrd) is
>>> not getting called.
>>
>> If _thrd_active(thrd) returns '1', that means there is an active
>> transfer still running or, if it has finished, you haven't called
>> pl330_update() to acknowledge that. pl330_update() calls _start() as
>> soon as it can.
>>
>> drivers/dma/pl330.c registers the irq handler in pl330_probe(), so
>> when
>> the transaction finishes, pl330_update() should clear it and call
>> _start(). If there is any outstanding transaction, it should start
>> straight away. If there isn't, it would mark the channel as free, so
>> _thrd_active() should return '0'. If _thrd_active() is still '1', then
>> something has gone wrong in the way.
>>
>> Does this shed some light?
>>
>
> Your patch makes the memcpy operation on dmatest.c and net DMA be frozen too
> as well as Samsung audio playback.
Is the IRQ correctly registered in drivers/dma/pl330.c:pl330_probe()?
Do you get interrupts when the transfer finish?
The only way I can think of that
ee3f615819404a9438b2dd01b7a39f276d2737f2 can break break something is
that you aren't calling pl330_update() at all.
> With our patch, common DMA memcpy sequence may be changed.
Which one is "our patch"? I'm sorry, I'm not subscribed to any of the
lists so I may have missed something.
Cheers,
Javi
next prev parent reply other threads:[~2011-11-28 16:36 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-09-19 17:11 [PATCH] ARM: pl330: Fix a race condition Javi Merino
2011-09-19 18:07 ` Jassi Brar
2011-09-20 13:36 ` Javi Merino
2011-10-05 12:57 ` Javi Merino
2011-10-06 9:10 ` [PATCH v2] " Javi Merino
2011-11-05 19:05 ` Thomas Abraham
2011-11-07 10:48 ` Javi Merino
2011-11-07 11:03 ` Thomas Abraham
2011-11-28 8:23 ` Boojin Kim
2011-11-28 16:36 ` Javi Merino [this message]
2011-11-29 3:41 ` Boojin Kim
2011-11-29 9:53 ` Javi Merino
2011-11-29 10:37 ` Jassi Brar
2011-12-07 7:52 ` Kukjin Kim
2011-12-07 10:01 ` Javi Merino
2011-12-07 20:54 ` Javi Merino
2011-12-09 11:58 ` Javi Merino
2011-12-09 13:04 ` Jassi Brar
2011-12-09 13:41 ` Javi Merino
2011-12-09 14:15 ` Jassi Brar
2011-12-09 14:52 ` Javi Merino
2011-12-09 16:50 ` Jassi Brar
2011-12-09 19:50 ` Javi Merino
2011-12-11 10:51 ` Jassi Brar
2011-12-11 15:09 ` Javi Merino
2011-12-11 17:10 ` Jassi Brar
2011-12-11 17:42 ` Javi Merino
2011-12-11 19:27 ` [PATCH] ARM: PL330: Fix driver freeze Javi Merino
2011-12-15 17:48 ` Javi Merino
2011-12-16 9:01 ` Tushar Behera
2011-12-16 6:27 ` Jassi Brar
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