linux-kernel - Re: [PATCH] spmi-pmic-arb: add irq tracepoints to the pmic-arb driver

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Date:	Thu, 28 May 2015 18:15:59 -0700
From:	Stephen Boyd <sboyd@...eaurora.org>
To:	Gilad Avidov <gavidov@...eaurora.org>
CC:	Ankit Gupta <ankgupta@...eaurora.org>, sdharia@...eaurora.org,
	ivan.ivanov@...aro.org, svarbanov@...sol.com, rostedt@...dmis.org,
	linux-arm-msm@...r.kernel.org, gregkh@...uxfoundation.org,
	collinsd@...eaurora.org, osvaldob@...eaurora.org,
	linux-kernel@...r.kernel.org, mlocke@...eaurora.org,
	galak@...eaurora.org, agross@...eaurora.org
Subject: Re: [PATCH] spmi-pmic-arb: add irq tracepoints to the pmic-arb driver

On 05/28/2015 04:02 PM, Gilad Avidov wrote:
> On Wed, 27 May 2015 13:06:29 -0700
> Stephen Boyd <sboyd@...eaurora.org> wrote:
>
>> On 05/27, Ankit Gupta wrote:
>>>> How is this any better than irq tracepoints that we already have
>>>> for generic irqs?
>>>>
>>> It is better than generic irq tracepoints because it provides bus
>>> specific information (sid and address(pid) of slave write), driver
>>> specific information (apid (pmic-peripheral) and func_num) and
>>> statistics (apid range).
>>> Recall that *slave* read/write cannot be traced by the spmi
>>> framework ftrace.
>>>
>> Don't we already get all this information based on how we map
>> interrupts to devices in DT? It feels to me that the same
>> argument here could be applied to all the random gpio expanders
>> and chained interrupt controllers that we support in the kernel.
>>
> We don't.
> We could get the same information if we had the irq-domain and hw-irq
> 32bit value. While these values are available from /proc/interrupt,
> they are not available from the irq event tracing.

Hm.. maybe we should add those trace events then into the irq domain 
layer? Or even extend the irq tracepoints to include the hw-irq and 
irq-domain name?

>
> This patch traces spmi slave-originated events. If we had one such
> slave we could cross information from both sources to filter the trace
> events. However, we have hundreds of transaction-capable spmi slaves.
>

Sorry I'm not following this point. If it was about tracing 
slave-originated events wouldn't it be more than irqs then?

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project

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