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Date:   Tue, 21 May 2019 12:32:14 +0200
From:   "hch@lst.de" <hch@lst.de>
To:     Fredrik Noring <noring@nocrew.org>
Cc:     Laurentiu Tudor <laurentiu.tudor@nxp.com>,
        Robin Murphy <robin.murphy@arm.com>, "hch@lst.de" <hch@lst.de>,
        "stern@rowland.harvard.edu" <stern@rowland.harvard.edu>,
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        "JuergenUrban@gmx.de" <JuergenUrban@gmx.de>,
        Leo Li <leoyang.li@nxp.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [RFC PATCH v2 0/3] prerequisites for device reserved local mem
 rework
Message-ID: <20190521103214.GB1973@lst.de>
References: <9d34015d-c219-179b-3141-4b0de3530ac3@arm.com> <20190514182931.GA2559@sx9> <0e5f3b86-7a80-eec7-691b-34a123194208@nxp.com> <20190515162858.GB17162@sx9> <ed63c117-610c-ea49-f45e-727be220745f@nxp.com> <20190516151548.GB53952@sx9> <5fa97254-3038-6fe7-a7e7-a267262049c6@nxp.com> <20190517174159.GA32450@sx9> <3c8897e9-218e-3fff-1735-816ffd30e908@nxp.com> <20190520154156.GA3664@sx9>
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On Mon, May 20, 2019 at 05:41:56PM +0200, Fredrik Noring wrote:
> 2. A device address is supplied as phys_addr_t phys to gen_pool_add_virt().
>    This seems to work in this particular DMA application, but there will be
>    problems if someone does phys_to_virt() or suchlike. Can this be improved
>    or clearly explained? gen_pool_virt_to_phys() searches in address ranges,
>    for example, so it appears the implementation uses phys quite carefully.

Well, it is a physical address, but not one that has a kernel mapping.
So phys_addr_t seems right here, but an additional comment explaining it
is not in the kernel mapping never hurts.