From: Robin Murphy <robin.murphy-5wv7dgnIgG8@public.gmane.org>
To: Christoph Hellwig <hch-jcswGhMUV9g@public.gmane.org>
Cc: linux-mips-6z/3iImG2C8G8FEW9MqTrA@public.gmane.org,
Greg Kroah-Hartman
<gregkh-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r@public.gmane.org>,
Paul Burton <paul.burton-8NJIiSa5LzA@public.gmane.org>,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org
Subject: Re: [PATCH 2/5] dma-mapping: move the dma_coherent flag to struct device
Date: Mon, 10 Sep 2018 17:06:40 +0100 [thread overview]
Message-ID: <aa6f49f8-24ea-f166-9c58-aecb13df0418@arm.com> (raw)
In-Reply-To: <20180910154747.GA23578-jcswGhMUV9g@public.gmane.org>
On 10/09/18 16:47, Christoph Hellwig wrote:
>>> --- a/kernel/dma/Kconfig
>>> +++ b/kernel/dma/Kconfig
>>> @@ -13,6 +13,9 @@ config NEED_DMA_MAP_STATE
>>> config ARCH_DMA_ADDR_T_64BIT
>>> def_bool 64BIT || PHYS_ADDR_T_64BIT
>>> +config ARCH_HAS_DMA_COHERENCE_H
>>> + bool
>>
>> This seems a little crude - is it unbearably churny to make an
>> asm-generic/dma-coherence.h implementation for everyone else?
>
> The case of having something else than the per-device flag is rather
> odd, and I hope we don't grow any new user in addition to mips.
>
> In fact I'm already thinking of ways to get rid of it for mips by
> e.g. iterating over all devices and just setting dma_coherent,
> but for now I wanted to solve the more urgen issues and tackle this
> later, as this unification blocks a few other things
Ah, somehow I started thinking that arm(64) would need to implement
their own as well, but I see the point now. In that case, TBH I'd be
quite happy with just a simple #ifdef CONFIG_MIPS in
linux/dma-noncoherent.h - plus then it looks even more like something
nobody else is expected to do.
>> Nits aside, this otherwise looks sane to me for factoring out the
>> equivalent Xen and arm64 DMA ops cases.
>
> Like this? :)
>
> http://git.infradead.org/users/hch/misc.git/shortlog/refs/heads/dma-maybe-coherent
Man, that's going to take me a *lot* of time to pick through. All those
horrendous subtleties that I barely remember!
Robin.
WARNING: multiple messages have this Message-ID (diff)
From: Robin Murphy <robin.murphy@arm.com>
To: Christoph Hellwig <hch@lst.de>
Cc: iommu@lists.linux-foundation.org,
Marek Szyprowski <m.szyprowski@samsung.com>,
Paul Burton <paul.burton@mips.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
linux-mips@linux-mips.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/5] dma-mapping: move the dma_coherent flag to struct device
Date: Mon, 10 Sep 2018 17:06:40 +0100 [thread overview]
Message-ID: <aa6f49f8-24ea-f166-9c58-aecb13df0418@arm.com> (raw)
In-Reply-To: <20180910154747.GA23578@lst.de>
On 10/09/18 16:47, Christoph Hellwig wrote:
>>> --- a/kernel/dma/Kconfig
>>> +++ b/kernel/dma/Kconfig
>>> @@ -13,6 +13,9 @@ config NEED_DMA_MAP_STATE
>>> config ARCH_DMA_ADDR_T_64BIT
>>> def_bool 64BIT || PHYS_ADDR_T_64BIT
>>> +config ARCH_HAS_DMA_COHERENCE_H
>>> + bool
>>
>> This seems a little crude - is it unbearably churny to make an
>> asm-generic/dma-coherence.h implementation for everyone else?
>
> The case of having something else than the per-device flag is rather
> odd, and I hope we don't grow any new user in addition to mips.
>
> In fact I'm already thinking of ways to get rid of it for mips by
> e.g. iterating over all devices and just setting dma_coherent,
> but for now I wanted to solve the more urgen issues and tackle this
> later, as this unification blocks a few other things
Ah, somehow I started thinking that arm(64) would need to implement
their own as well, but I see the point now. In that case, TBH I'd be
quite happy with just a simple #ifdef CONFIG_MIPS in
linux/dma-noncoherent.h - plus then it looks even more like something
nobody else is expected to do.
>> Nits aside, this otherwise looks sane to me for factoring out the
>> equivalent Xen and arm64 DMA ops cases.
>
> Like this? :)
>
> http://git.infradead.org/users/hch/misc.git/shortlog/refs/heads/dma-maybe-coherent
Man, that's going to take me a *lot* of time to pick through. All those
horrendous subtleties that I barely remember!
Robin.
next prev parent reply other threads:[~2018-09-10 16:06 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-10 6:05 merge dma_direct_ops and dma_noncoherent_ops v2 Christoph Hellwig
2018-09-10 6:05 ` Christoph Hellwig
[not found] ` <20180910060533.27172-1-hch-jcswGhMUV9g@public.gmane.org>
2018-09-10 6:05 ` [PATCH 1/5] MIPS: don't select DMA_MAYBE_COHERENT from DMA_PERDEV_COHERENT Christoph Hellwig
2018-09-10 6:05 ` Christoph Hellwig
2018-09-10 6:05 ` [PATCH 2/5] dma-mapping: move the dma_coherent flag to struct device Christoph Hellwig
2018-09-10 6:05 ` Christoph Hellwig
2018-09-10 15:19 ` Robin Murphy
2018-09-10 15:47 ` Christoph Hellwig
[not found] ` <20180910154747.GA23578-jcswGhMUV9g@public.gmane.org>
2018-09-10 16:06 ` Robin Murphy [this message]
2018-09-10 16:06 ` Robin Murphy
2018-09-11 6:48 ` Christoph Hellwig
2018-09-11 6:58 ` Christoph Hellwig
2018-09-10 16:13 ` Greg Kroah-Hartman
[not found] ` <20180910161350.GA10380-U8xfFu+wG4EAvxtiuMwx3w@public.gmane.org>
2018-09-11 6:46 ` Christoph Hellwig
2018-09-11 6:46 ` Christoph Hellwig
[not found] ` <20180911064636.GA6214-jcswGhMUV9g@public.gmane.org>
2018-09-11 8:19 ` Greg Kroah-Hartman
2018-09-11 8:19 ` Greg Kroah-Hartman
2018-09-10 6:05 ` [PATCH 4/5] dma-mapping: consolidate the dma mmap implementations Christoph Hellwig
2018-09-10 6:05 ` Christoph Hellwig
2018-09-10 6:05 ` [PATCH 5/5] dma-mapping: support non-coherent devices in dma_common_get_sgtable Christoph Hellwig
2018-09-10 6:05 ` Christoph Hellwig
2018-09-10 6:05 ` [PATCH 3/5] dma-mapping: merge direct and noncoherent ops Christoph Hellwig
-- strict thread matches above, loose matches on Subject: below --
2018-08-27 14:50 (unknown), Christoph Hellwig
2018-08-27 14:50 ` [PATCH 2/5] dma-mapping: move the dma_coherent flag to struct device Christoph Hellwig
2018-08-31 20:11 ` Paul Burton
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