linux-kernel - Re: [PATCH V12 3/7] dma: add Qualcomm Technologies HIDMA management driver

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Date:	Wed, 20 Jan 2016 17:18:29 -0500
From:	Sinan Kaya <okaya@...eaurora.org>
To:	Mark Rutland <mark.rutland@....com>
Cc:	Marc Zyngier <marc.zyngier@....com>, dmaengine@...r.kernel.org,
	timur@...eaurora.org, devicetree@...r.kernel.org,
	cov@...eaurora.org, vinod.koul@...el.com, jcm@...hat.com,
	agross@...eaurora.org, arnd@...db.de,
	linux-arm-msm@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	kvmarm@...ts.cs.columbia.edu, christoffer.dall@...aro.org
Subject: Re: [PATCH V12 3/7] dma: add Qualcomm Technologies HIDMA management
 driver

Mark,

On 1/15/2016 11:01 AM, Sinan Kaya wrote:
>> I'm concerned with how this is safe, and with the userspace interface.
>> > e.g. if the user wants to up the QoS for a VM, how to they find the
>> > right channel in sysfs  to alter?
> The HW supports changing the QoS values on the flight. In order to locate the
> object, I'm exporting a 
> 
> I tried to address your concern on v10 last series. Here is brief summary.
> 
> Each channel device has a sysfs entry named chid.
> What:		/sys/devices/platform/hidma-*/chid
> +		/sys/devices/platform/QCOM8061:*/chid
> 
> 
> Each management object has one priority and weight file per channel.
> +What:		/sys/devices/platform/hidma-mgmt*/chanops/chan*/priority
> +		/sys/devices/platform/QCOM8060:*/chanops/chan*/priority
> 
> Suppose you want to change the priority of a channel you assigned to guess,
> the userspace application goes and reads the chid value of the channel.
> 
> Then goes to chanops/chan<chid>/ directory and can change priority and weight 
> parameters here.
> 
> Here is how the directory looks like. QCOM8060:00 is a management object.
> QCOM8061:0x are the channel objects.
> 
> /sys/devices/platform/QCOM8060:00# ls
> QCOM8061:00
> QCOM8061:01
> QCOM8061:02
> QCOM8061:03
> QCOM8061:04
> QCOM8061:05
> chanops
> <other common attributes>
> 
> 
> 
> 


Did this answer your question? 

I'm capturing all the questions and answers as FAQ into the cover letter as I keep
repeating myself for every single reviewer.

Besides from the "lack of documentation", is there any code related change you'd like to
discuss in the series.


-- 
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