Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Message-ID: <5A6563FA.8080602@rock-chips.com>
Date:   Mon, 22 Jan 2018 12:09:30 +0800
From:   JeffyChen <jeffy.chen@rock-chips.com>
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:19.0) Gecko/20130126 Thunderbird/19.0
MIME-Version: 1.0
To:     Randy Li <randy.li@rock-chips.com>,
        Robin Murphy <robin.murphy@arm.com>,
        linux-kernel@vger.kernel.org, tfiga@chromium.org
CC:     Mark Rutland <mark.rutland@arm.com>, devicetree@vger.kernel.org,
        xxm@rock-chips.com, Joerg Roedel <joro@8bytes.org>,
        jcliang@chromium.org, linux-rockchip@lists.infradead.org,
        iommu@lists.linux-foundation.org, Rob Herring <robh+dt@kernel.org>,
        linux-arm-kernel@lists.infradead.org,
        Heiko Stuebner <heiko@sntech.de>
Subject: Re: [PATCH v4 08/13] iommu/rockchip: Control clocks needed to access
 the IOMMU
References: <20180118115251.5542-1-jeffy.chen@rock-chips.com> <20180118115251.5542-9-jeffy.chen@rock-chips.com> <c188e6a9-744c-d984-545c-408607f35cc9@arm.com> <5A60AE41.2050101@rock-chips.com> <1f4b3c0d-1414-0012-a072-f4a11f432c21@rock-chips.com> <5A654925.9020203@rock-chips.com>
In-Reply-To: <5A654925.9020203@rock-chips.com>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Hi Randy,

On 01/22/2018 10:15 AM, JeffyChen wrote:
> Hi Randy,
>
> On 01/22/2018 09:18 AM, Randy Li wrote:
>>>
>> Also the power domain driver could manage the clocks as well, I would
>> suggest to use pm_runtime_*.
>
> actually the clocks required by pm domain may not be the same as what we
> want to control here, there might be some clocks only be needed when
> accessing mmu registers.
>
> but i'm not very sure about that, will confirm it with Simon Xue.

confirmed with Simon, there might be some iommus don't have a pd, and 
the CONFIG_PM could be disabled.

so it might be better to control clocks in iommu driver itself.