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From: viresh.kumar@st.com (viresh kumar)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 1/6] dmaengine/dw_dmac: Replace spin_lock_bh with	irqsave variants
Date: Wed, 27 Apr 2011 11:29:49 +0530	[thread overview]
Message-ID: <4DB7B0D5.5050504@st.com> (raw)
In-Reply-To: <20110426203306.GC17290@n2100.arm.linux.org.uk>

On 04/27/2011 02:03 AM, Russell King - ARM Linux wrote:
> On Tue, Apr 19, 2011 at 11:55:45AM +0530, viresh kumar wrote:
>> This must have been added in dw_dma_chan instead :(
>> Will resend it.
> 
> Even that doesn't work.  It has to be a local variable.

Hello,

There are two kinds of locks taken in dw_dmac: spin_lock_bh and spin_lock.
spin_lock_bh is taken from routines called from external drivers and spin_lock
taken inside tasklet.
For reasons mentioned earlier, spin_lock_bh has to be replaced with spin_lock_irqsave.

Now, Is simple spin_lock() sufficient inside tasklet?? As dma API's can be called
from interrupt context (which will try to take spin_lock_irqsave).

I think spin_lock must be replaced with irqsave variants, even in tasklet.
Now if we do that, do we need this tasklet at all??

-- 
viresh

WARNING: multiple messages have this Message-ID (diff)
From: viresh kumar <viresh.kumar@st.com>
To: Russell King - ARM Linux <linux@arm.linux.org.uk>,
	"vinod.koul@intel.com" <vinod.koul@intel.com>
Cc: "dan.j.williams@intel.com" <dan.j.williams@intel.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>,
	Armando VISCONTI <armando.visconti@st.com>,
	Shiraz HASHIM <shiraz.hashim@st.com>, amitgoel <amit.goel@st.com>,
	"viresh.linux@gmail.com" <viresh.linux@gmail.com>,
	"jamie@jamieiles.com" <jamie@jamieiles.com>
Subject: Re: [PATCH 1/6] dmaengine/dw_dmac: Replace spin_lock_bh with	irqsave variants
Date: Wed, 27 Apr 2011 11:29:49 +0530	[thread overview]
Message-ID: <4DB7B0D5.5050504@st.com> (raw)
In-Reply-To: <20110426203306.GC17290@n2100.arm.linux.org.uk>

On 04/27/2011 02:03 AM, Russell King - ARM Linux wrote:
> On Tue, Apr 19, 2011 at 11:55:45AM +0530, viresh kumar wrote:
>> This must have been added in dw_dma_chan instead :(
>> Will resend it.
> 
> Even that doesn't work.  It has to be a local variable.

Hello,

There are two kinds of locks taken in dw_dmac: spin_lock_bh and spin_lock.
spin_lock_bh is taken from routines called from external drivers and spin_lock
taken inside tasklet.
For reasons mentioned earlier, spin_lock_bh has to be replaced with spin_lock_irqsave.

Now, Is simple spin_lock() sufficient inside tasklet?? As dma API's can be called
from interrupt context (which will try to take spin_lock_irqsave).

I think spin_lock must be replaced with irqsave variants, even in tasklet.
Now if we do that, do we need this tasklet at all??

-- 
viresh

  parent reply	other threads:[~2011-04-27  5:59 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-04-18 10:49 [PATCH 1/6] dmaengine/dw_dmac: Replace spin_lock_bh with irqsave variants Viresh Kumar
2011-04-18 10:49 ` Viresh Kumar
2011-04-18 10:50 ` [PATCH 2/6] dmaengine/dw_dmac: Enable resubmission from callback routine Viresh Kumar
2011-04-18 10:50   ` Viresh Kumar
2011-04-19  6:12   ` Koul, Vinod
2011-04-19  6:12     ` Koul, Vinod
2011-04-19  6:23     ` viresh kumar
2011-04-19  6:23       ` viresh kumar
2011-04-19  6:33       ` Koul, Vinod
2011-04-19  6:33         ` Koul, Vinod
2011-04-19  6:46         ` viresh kumar
2011-04-19  6:46           ` viresh kumar
2011-04-26 20:31     ` Russell King - ARM Linux
2011-04-26 20:31       ` Russell King - ARM Linux
2011-04-18 10:50 ` [PATCH 3/6] dmaengine/dw_dmac: call dwc_descriptor_complete from dwc_control with lock held Viresh Kumar
2011-04-18 10:50   ` Viresh Kumar
2011-04-18 10:50 ` [PATCH 4/6] dmaengine/dw_dmac: don't call callback routine in case dmaengine_terminate_all() is called Viresh Kumar
2011-04-18 10:50   ` Viresh Kumar
2011-04-18 10:50 ` [PATCH 5/6] dmaengine/dw_dmac: set residue as total len in dwc_tx_status if status is !DMA_SUCCESS Viresh Kumar
2011-04-18 10:50   ` Viresh Kumar
2011-04-18 10:50 ` [PATCH 6/6] dmaengine/dw_dmac: Divide one sg to many desc, if sg len is greater than DWC_MAX_COUNT Viresh Kumar
2011-04-18 10:50   ` Viresh Kumar
2011-04-19  6:25 ` [PATCH 1/6] dmaengine/dw_dmac: Replace spin_lock_bh with irqsave variants viresh kumar
2011-04-19  6:25   ` viresh kumar
2011-04-26 20:33   ` Russell King - ARM Linux
2011-04-26 20:33     ` Russell King - ARM Linux
2011-04-27  3:47     ` viresh kumar
2011-04-27  3:47       ` viresh kumar
2011-04-27  5:59     ` viresh kumar [this message]
2011-04-27  5:59       ` viresh kumar
2011-04-27  7:28       ` Russell King - ARM Linux
2011-04-27  7:28         ` Russell King - ARM Linux
2011-04-26 20:30 ` Russell King - ARM Linux
2011-04-26 20:30   ` Russell King - ARM Linux

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