Re: [PATCH V5 2/3] mm: dmapool: Align to ARCH_DMA_MINALIGN innon-coherent DMA mode
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"<h...@infradead.org>; Date: Mon, Sep 18, 2017 01:22 PM To: "Huacai Chen"<che...@lemote.com>; Cc: "Andrew Morton"<a...@linux-foundation.org>; "Fuxin Zhang"<zhan...@lemote.com>; "linux-mm"<linux...@kvack.org>; "linux-kernel"<linux-kernel@vger.kernel.org>; "stable"<sta...@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.
Re: [PATCH V5 2/3] mm: dmapool: Align to ARCH_DMA_MINALIGN innon-coherent DMA mode
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"; Date: Mon, Sep 18, 2017 01:22 PM To: "Huacai Chen"; Cc: "Andrew Morton"; "Fuxin Zhang"; "linux-mm"; "linux-kernel"; "stable"; 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.
