Subject: Re: [PATCH 2/2] dma: add Qualcomm Technologies HIDMA channel driver
To: Timur Tabi <timur@codeaurora.org>, Arnd Bergmann <arnd@arndb.de>
References: <1446174501-8870-1-git-send-email-okaya@codeaurora.org>
 <5741892.rRLhcI7KQG@wuerfel> <5633E442.3010003@codeaurora.org>
 <4552697.VhjWnxQoIo@wuerfel> <56365F0D.6010508@codeaurora.org>
 <56367433.60806@codeaurora.org>
Cc: dmaengine@vger.kernel.org, cov@codeaurora.org, jcm@redhat.com,
        Rob Herring <robh+dt@kernel.org>, Pawel Moll <pawel.moll@arm.com>,
        Mark Rutland <mark.rutland@arm.com>,
        Ian Campbell <ijc+devicetree@hellion.org.uk>,
        Kumar Gala <galak@codeaurora.org>, Vinod Koul <vinod.koul@intel.com>,
        Dan Williams <dan.j.williams@intel.com>, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org
From: Sinan Kaya <okaya@codeaurora.org>
Message-ID: <5636759A.4040506@codeaurora.org>
Date: Sun, 1 Nov 2015 15:27:06 -0500
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On 11/1/2015 3:21 PM, Timur Tabi wrote:
> Sinan Kaya wrote:
>> However, after issuing the command; I still need to wait some amount of
>> time until hardware acknowledges the commands like reset/enable/disable.
>> These are relatively faster operations happening in microseconds. That's
>> why, I have mdelay there.
>
> Can you use readl_poll_timeout()?
>
Yes, I'm changing them to readl_poll_timeout after looking at the 
workqueue vs. expected delay requirements. I decided to stick with 
polled read.

First, I missed the point here that mdelay is discouraged.
https://www.kernel.org/doc/Documentation/timers/timers-howto.txt

According to same document, msleep can sleep up to 20ms which is not 
what I want.

This code is trying to sleep 10ms maximum and treating longer durations 
as failures.

readl_poll_timeout calls usleep_range that seems to satisfy what I'm 
looking for.

-- 
Sinan Kaya
Qualcomm Technologies, Inc. on behalf of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a 
Linux Foundation Collaborative Project
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