From: javi.merino@arm•com (Javi Merino)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH v2] ARM: pl330: Fix a race condition
Date: Tue, 29 Nov 2011 09:53:30 +0000 [thread overview]
Message-ID: <4ED4AB9A.3060807@arm.com> (raw)
In-Reply-To: <000e01ccae48$d76a7ba0$863f72e0$%kim@samsung.com>
On 29/11/11 03:41, 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?
> Sure. IRQ works well.
Ok, so can you check if pl330_update() is correctly marking the request
as free? Do you know if there is another request in the queue when that
happens?
Thomas, you said in a previous email that _thrd_active() always returned
'1'. Was that after a request in req[0] finished?
- If so, can you check that MARK_FREE was actually called for that
request in pl330_update()?
- If it was after a request in req[1] finished and there was a
request already waiting in req[0], can you debug why _start()
didn't activate it.
Cheers,
Javi
next prev parent reply other threads:[~2011-11-29 9:53 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
2011-11-29 3:41 ` Boojin Kim
2011-11-29 9:53 ` Javi Merino [this message]
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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