From: 陈华才 <chenhc@lemote.com>
To: "Christoph Hellwig" <hch@infradead.org>
Cc: "Andrew Morton" <akpm@linux-foundation.org>,
"Fuxin Zhang" <zhangfx@lemote.com>, linux-mm <linux-mm@kvack.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
stable <stable@vger.kernel.org>
Subject: Re: [PATCH V5 2/3] mm: dmapool: Align to ARCH_DMA_MINALIGN innon-coherent DMA mode
Date: Mon, 18 Sep 2017 14:55:08 +0800 [thread overview]
Message-ID: <tencent_68A77D143FD0DC0E5D6D1C1E@qq.com> (raw)
In-Reply-To: <20170918052208.GB29118@infradead.org>
Hi, Christoph,
Maybe you missed something.
1, pool_alloc_page() use dma_alloc_coherent() to allocate pool pages, and of course these pages are aligned to ARCH_DMA_MINALIGN.
2, dma_pool_alloc() is the element allocator, but it doesn't use dma_alloc_coherent(). Elements only align to pool->size, but pool->size is usually less than ARCH_DMA_MINALIGN.
3, ARCH_DMA_MINALIGN is now only used in serveral drivers, no dma_ops use it.
Huacai
------------------ Original ------------------
From: "Christoph Hellwig"<hch@infradead.org>;
Date: Mon, Sep 18, 2017 01:22 PM
To: "Huacai Chen"<chenhc@lemote.com>;
Cc: "Andrew Morton"<akpm@linux-foundation.org>; "Fuxin Zhang"<zhangfx@lemote.com>; "linux-mm"<linux-mm@kvack.org>; "linux-kernel"<linux-kernel@vger.kernel.org>; "stable"<stable@vger.kernel.org>;
Subject: Re: [PATCH V5 2/3] mm: dmapool: Align to ARCH_DMA_MINALIGN innon-coherent DMA mode
The dmapool code uses dma_alloc_coherent to allocate each element,
and dma_alloc_coherent must align to ARCH_DMA_MINALIGN already.
If you implementation doesn't do that it needs to be fixed.
next prev parent reply other threads:[~2017-09-18 6:55 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-18 4:22 [PATCH V5 2/3] mm: dmapool: Align to ARCH_DMA_MINALIGN in non-coherent DMA mode Huacai Chen
2017-09-18 5:22 ` Christoph Hellwig
2017-09-18 6:55 ` 陈华才 [this message]
2017-09-18 9:44 ` [V5, " Robin Murphy
2017-09-18 15:51 ` Christoph Hellwig
2017-09-19 2:23 ` [V5, 2/3] mm: dmapool: Align to ARCH_DMA_MINALIGN innon-coherent " 陈华才
2017-09-18 15:45 ` [PATCH V5 2/3] mm: dmapool: Align to ARCH_DMA_MINALIGN in non-coherent " Christoph Hellwig
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