From: javi.merino@arm•com (Javi Merino)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH v2] ARM: pl330: Fix a race condition
Date: Wed, 07 Dec 2011 10:01:45 +0000 [thread overview]
Message-ID: <4EDF3989.3060108@arm.com> (raw)
In-Reply-To: <03f001ccb4b5$3441f5c0$9cc5e140$%kim@samsung.com>
On 07/12/11 07:52, Kukjin Kim wrote:
> Jassi Brar wrote:
>>
>> On 29 November 2011 15:23, Javi Merino <javi.merino@arm•com> 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.
>>>
>> Javi, could you please check if you too get the memcpy failure with
>> dmatest ?
>
> (Please adding me in this thread)
>
> Hi Javi,
> How was going on the test? If any update, please let us know.
I'm currently very busy at work, I'll run it as soon as I can. This
appears to happen only in exynos, can't anybody else help with the
debugging?
Cheers,
Javi
next prev parent reply other threads:[~2011-12-07 10:01 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
2011-11-29 10:37 ` Jassi Brar
2011-12-07 7:52 ` Kukjin Kim
2011-12-07 10:01 ` Javi Merino [this message]
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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