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Reply-To: alex.popov@linux.com
Subject: Re: [PATCH v3 1/3] powerpc/512x: add LocalPlus Bus FIFO device driver
References: <1443115737-3948-1-git-send-email-alex.popov@linux.com>
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To: Timur Tabi <timur@tabi.org>,
 Benjamin Herrenschmidt <benh@kernel.crashing.org>,
 Paul Mackerras <paulus@samba.org>, Michael Ellerman <mpe@ellerman.id.au>,
 Anatolij Gustschin <agust@denx.de>, Rob Herring <robh@kernel.org>,
 Grant Likely <grant.likely@linaro.org>,
 Dan Williams <dan.j.williams@intel.com>, Vinod Koul <vinod.koul@intel.com>,
 Pawel Moll <pawel.moll@arm.com>, Mark Rutland <mark.rutland@arm.com>,
 Ian Campbell <ijc+devicetree@hellion.org.uk>,
 Kumar Gala <galak@codeaurora.org>, linuxppc-dev@lists.ozlabs.org,
 dmaengine@vger.kernel.org, devicetree@vger.kernel.org,
 linux-kernel@vger.kernel.org, Alexander Popov <alex.popov@linux.com>
From: Alexander Popov <alex.popov@linux.com>
Message-ID: <560A30DF.9050900@linux.com>
Date: Tue, 29 Sep 2015 09:34:07 +0300
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On 28.09.2015 16:18, Timur Tabi wrote:
> Alexander Popov wrote:
>> The only question I have: why calling dma_unmap_single() from within
>> a spinlock is a bad practice?
> 
> I don't know, but usually functions that allocate or free memory cannot be
> called from within a spinlock.  You need to check that.  Since the MPC5121
> is a single-core CPU, you might not notice if you're doing something wrong.

I've double-checked the code and LDD and don't see any reason to avoid
calling dma_unmap_single() from interrupt context and within spinlock.

Please correct me if I'm wrong.
Thanks.

Best regards,
Alexander