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From: Jouko Haapaluoma <jouko.haapaluoma@wapice.com>
To: Nicolas Ferre <nicolas.ferre@atmel.com>
Cc: "Sami Pietikäinen" <Sami.Pietikainen@wapice.com>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"dmaengine@vger.kernel.org" <dmaengine@vger.kernel.org>,
	"vinod.koul@intel.com" <vinod.koul@intel.com>
Subject: RE: [RFC PATCH 0/2] dmaengine: at_hdmac: fix locking according to slave DMA requirements
Date: Fri, 31 Jan 2014 10:56:25 +0000	[thread overview]
Message-ID: <C9F8415089354E4FB76F4548B3515AF484289B2A@edb1.wapice.localdomain> (raw)
In-Reply-To: <cover.1390832343.git.nicolas.ferre@atmel.com>

Hi

Thanks for the patches. We got the DMA working for now but the tasklet_disable() and tasklet_enable() had to be removed from atc_control().

If the device driver calls dmaengine_terminate_all() from the callback (like in our previous deadlock example), the tasklet_disable() will cause
another deadlock because the tasklet will then wait for itself to close.

The tasklet_disable() seems to be used to ensure that no tasklet is running when terminating the DMA transfers. This prevents the terminate_all from
happening in between the critical sections in the tasklet which are locked with atchan->lock. Maybe the tasklet needs to be implemented so that it can
detect and recover if the terminate_all was called in between the critical sections in the tasklet?

BR,
Jouko Haapaluoma

      parent reply	other threads:[~2014-01-31 10:56 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <C9F8415089354E4FB76F4548B3515AF484286F61@edb1.wapice.localdomain>
2014-01-27 14:23 ` [RFC PATCH 0/2] dmaengine: at_hdmac: fix locking according to slave DMA requirements Nicolas Ferre
2014-01-27 14:23   ` [PATCH 1/2] dmaengine: at_hdmac: remove the call to issue_pending from tx_status Nicolas Ferre
2014-01-27 14:23   ` [PATCH 2/2] dmaengine: at_hdmac: run callback function with no lock held nor interrupts disabled Nicolas Ferre
2014-03-11 10:56     ` Vinod Koul
2014-01-31 10:56   ` Jouko Haapaluoma [this message]

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