From: Mark Salyzyn <salyzyn@android.com>
To: Christoph Hellwig <hch@lst.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
linux-kernel@vger.kernel.org, kernel-team@android.com,
Andrew Morton <akpm@linux-foundation.org>,
Yue Hu <huyue2@yulong.com>, Mike Rapoport <rppt@linux.ibm.com>,
Will Deacon <will@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ryohei Suzuki <ryh.szk.cmnty@gmail.com>,
Doug Berger <opendmb@gmail.com>,
Andrey Konovalov <andreyknvl@google.com>,
Peng Fan <peng.fan@nxp.com>,
linux-mm@kvack.org, Robin Murphy <robin.murphy@arm.com>
Subject: Re: [PATCH] mm: export cma alloc and release
Date: Mon, 7 Oct 2019 10:06:40 -0700 [thread overview]
Message-ID: <22ef8c58-2595-aba7-f72e-a2319622430d@android.com> (raw)
In-Reply-To: <20191007165315.GA10317@lst.de>
On 10/7/19 9:53 AM, Christoph Hellwig wrote:
> On Mon, Oct 07, 2019 at 09:50:31AM -0700, Mark Salyzyn wrote:
>> On 10/5/19 1:37 AM, Christoph Hellwig wrote:
>>> On Thu, Oct 03, 2019 at 09:55:28AM +0100, Catalin Marinas wrote:
>>>> Aren't drivers supposed to use the DMA API for such allocations rather
>>>> than invoking cma_*() directly?
>>> Yes, they are.
>> We have an engineer assigned to rewriting the ion memory driver to use
>> dma_buf interfaces. Hopefully that effort will solve the problem of
>> requiring these interfaces to be exported so that that driver (and others)
>> can be modularized.
>>
>> Thanks for the reviews, drop this patch from the list and we will regroup,
>> and accept that standing code in the kernel can not be modularized for the
>> moment.
> How is that different from the "DMA-BUF Heaps (destaging ION)" series
> floating around?
IDK, I am asking around because I am only superficially aware of that
effort. Please view this as the left hand does not know what the right
hand is doing. My issue was with a series of out-of-tree drivers that
use the calls, and noted that currently the ion driver is using them as
well, as rationalization for a 'user' for the export. I am pushing back
on those out-of-tree drivers to switch their CMA interfaces to a modern
approach as a result of these reviews; the result of this review had a
positive effect because I was considering exporting them in the Android
distro as a minimum, and now I am soundly rejecting that approach.
Sincerely -- Mark Salyzyn
prev parent reply other threads:[~2019-10-07 17:06 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-02 21:22 [PATCH] mm: export cma alloc and release Mark Salyzyn
2019-10-03 8:55 ` Catalin Marinas
2019-10-05 8:37 ` Christoph Hellwig
2019-10-07 16:50 ` Mark Salyzyn
2019-10-07 16:53 ` Christoph Hellwig
2019-10-07 17:06 ` Mark Salyzyn [this message]
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