From: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
To: Catalin Marinas <catalin.marinas@arm.com>
Cc: linux-rpi-kernel@lists.infradead.org, f.fainelli@gmail.com,
marc.zyngier@arm.com, Will Deacon <will@kernel.org>,
linux-kernel@vger.kernel.org, robh+dt@kernel.org,
linux-mm@kvack.org, mbrugger@suse.com, wahrenst@gmx.net,
linux-riscv@lists.infradead.org, phill@raspberrypi.org,
robin.murphy@arm.com, hch@lst.de,
linux-arm-kernel@lists.infradead.org, m.szyprowski@samsung.com
Subject: Re: [PATCH v4 3/4] arm64: use both ZONE_DMA and ZONE_DMA32
Date: Mon, 09 Sep 2019 10:46:39 +0200 [thread overview]
Message-ID: <7fc8f4d9a992ef9e92e0d188d32c8763a11d39e3.camel@suse.de> (raw)
In-Reply-To: <20190908212711.GA84759@huawei_p9_lite.cambridge.arm.com>
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On Sun, 2019-09-08 at 22:27 +0100, Catalin Marinas wrote:
> On Fri, Sep 06, 2019 at 02:06:14PM +0200, Nicolas Saenz Julienne wrote:
> > @@ -430,7 +454,7 @@ void __init arm64_memblock_init(void)
> >
> > high_memory = __va(memblock_end_of_DRAM() - 1) + 1;
> >
> > - dma_contiguous_reserve(arm64_dma32_phys_limit);
> > + dma_contiguous_reserve(arm64_dma_phys_limit ? : arm64_dma32_phys_limit);
> > }
> >
> > void __init bootmem_init(void)
> > @@ -534,6 +558,7 @@ static void __init free_unused_memmap(void)
> > void __init mem_init(void)
> > {
> > if (swiotlb_force == SWIOTLB_FORCE ||
> > + max_pfn > (arm64_dma_phys_limit >> PAGE_SHIFT) ||
> > max_pfn > (arm64_dma32_phys_limit >> PAGE_SHIFT))
> > swiotlb_init(1);
>
> So here we want to initialise the swiotlb only if we need bounce
> buffers. Prior to this patch, we assumed that swiotlb is needed if
> max_pfn is beyond the reach of 32-bit devices. With ZONE_DMA, we need to
> lower this limit to arm64_dma_phys_limit.
>
> If ZONE_DMA is enabled, just comparing max_pfn with arm64_dma_phys_limit
> is sufficient since the dma32 one limit always higher. However, if
> ZONE_DMA is disabled, arm64_dma_phys_limit is 0, so we may initialise
> swiotlb unnecessarily. I guess you need a similar check to the
> dma_contiguous_reserve() above.
Of course.
>
> With that:
>
> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
>
> Unless there are other objections, I can queue this series for 5.5 in a
> few weeks time (too late for 5.4).
Thanks!
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next prev parent reply other threads:[~2019-09-09 8:47 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-06 12:06 [PATCH v4 0/4] Raspberry Pi 4 DMA addressing support Nicolas Saenz Julienne
2019-09-06 12:06 ` [PATCH v4 1/4] arm64: mm: use arm64_dma_phys_limit instead of calling max_zone_dma_phys() Nicolas Saenz Julienne
2019-09-06 12:06 ` [PATCH v4 2/4] arm64: rename variables used to calculate ZONE_DMA32's size Nicolas Saenz Julienne
2019-09-06 12:06 ` [PATCH v4 3/4] arm64: use both ZONE_DMA and ZONE_DMA32 Nicolas Saenz Julienne
2019-09-08 21:27 ` Catalin Marinas
2019-09-09 8:46 ` Nicolas Saenz Julienne [this message]
2019-09-06 12:06 ` [PATCH v4 4/4] mm: refresh ZONE_DMA and ZONE_DMA32 comments in 'enum zone_type' Nicolas Saenz Julienne
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