linux-kernel - Re: [PATCHv3 0/5] arm-cci400: PMU monitoring support on ARM64

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Date:	Tue, 10 Mar 2015 16:11:15 +0000
From:	"Suzuki K. Poulose" <Suzuki.Poulose@....com>
To:	Nicolas Pitre <nicolas.pitre@...aro.org>
CC:	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
	Kukjin Kim <kgene@...nel.org>,
	Abhilash Kesavan <a.kesavan@...sung.com>,
	Arnd Bergmann <arnd@...db.de>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Liviu Dudau <Liviu.Dudau@....com>,
	Lorenzo Pieralisi <Lorenzo.Pieralisi@....com>,
	Olof Johansson <olof@...om.net>,
	Pawel Moll <Pawel.Moll@....com>,
	Punit Agrawal <Punit.Agrawal@....com>,
	Sudeep Holla <Sudeep.Holla@....com>,
	Will Deacon <Will.Deacon@....com>,
	Catalin Marinas <Catalin.Marinas@....com>
Subject: Re: [PATCHv3 0/5] arm-cci400: PMU monitoring support on ARM64

On 10/03/15 16:09, Nicolas Pitre wrote:
> On Tue, 10 Mar 2015, Suzuki K. Poulose wrote:
>
>> From: "Suzuki K. Poulose" <suzuki.poulose@....com>
>>
>> This series enables the PMU monitoring support for CCI400 on ARM64.
>> The existing CCI400 driver code is a mix of PMU driver and the MCPM
>> driver code. The MCPM driver is only used on ARM(32) and contains
>> arm32 assembly and hence can't be built on ARM64. This patch splits
>> the code to
>>
>>   - ARM_CCI400_PORT_CTRL driver - depends on ARM && V7
>>   - ARM_CCI400_PMU driver
>>
>> Accessing the Peripheral ID2 register(PID2) on CCI-400, to detect
>> the revision of the chipset, is a secure operation. Hence, it prevents
>> us from running this on non-secure platforms. The issue is overcome by
>> explicitly mentioning the revision number of the CCI PMU in the device tree
>> binding. The device-tree binding has been updated with the new bindings.
>>
>> i.e,	arm-cci-400-pmu,r0 => revision 0
>> 	arm-cci-400-pmu,r1 => revision 1
>> 	arm-cci-400-pmu => (old) DEPRECATED
>>
>> The old binding has been DEPRECATED and must be used only on ARM32
>> system with secure access. We don't have a reliable dynamic way to detect
>> if the system is running secure. This series tries to use the best safe
>> method by relying on the availability of MCPM(as it was prior to the series).
>> It is upto the MCPM platform driver to decide, if the system is secure before
>> it goes ahead and registers its drivers and pokes the CCI. This series doesn't
>> address/solve the problem of MCPM. I will be happy to use a better approach,
>> if there is any.
>>
>> Tested on (non-secure)TC2 and A53x2.
>
> Would be nice if you could also test it on secure TC2 making sure MCPM
> is still functional.

Sudeep is testing those bits.
>
> For patches 1, 3 and 4, you may add:
>
> Acked-by: Nicolas Pitre <nico@...aro.org>
>
> Patches 2 and 5 are purely PMU stuff and out of my area of expertise.
>

Thanks
Suzuki


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