On Aug 24, 2012, at 5:50 AM, Shaohui Xie wrote:
> PowerPC platform only supports ZONE_DMA zone for 64bit kernel, so all the
> memory will be put into this zone. If the memory size is greater than
> the device's DMA capability and device uses dma_alloc_coherent to allocate
> memory, it will get an address which is over the device's DMA addressing,
> the device will fail.
>
> So we split the memory to two zones: zone ZONE_DMA32 & ZONE_NORMAL, since
> we already allocate PCICSRBAR/PEXCSRBAR right below the 4G boundary (if the
> lowest PCI address is above 4G), so we constrain the DMA zone ZONE_DMA32
> to 2GB, also, we clear flag __GFP_DMA & __GFP_DMA32 and set __GFP_DMA32 only
> if the device's dma_mask < total memory size. By doing this, devices which
> cannot DMA all the memory will be limited to ZONE_DMA32, but devices which
> can DMA all the memory will not be affected by this limitation.
>
> Signed-off-by: Shaohui Xie <shaohui....@freescale.com>
> Signed-off-by: Mingkai Hu <mingkai...@freescale.com>
> Signed-off-by: Chen Yuanquan <b41...@freescale.com>
> ---
> changes for v2:
> 1. use a config option for using two zones (ZONE_DMA32 & ZONE_NORMAL) in
> freescale 64 bit kernel.
>
> arch/powerpc/Kconfig | 3 +++
> arch/powerpc/kernel/dma.c | 15 +++++++++++++++
> arch/powerpc/mm/mem.c | 4 ++++
> 3 files changed, 22 insertions(+), 0 deletions(-)
Ben,
What's the feeling of doing this on ppc64 always?
- k
>
> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> index 352f416..a96fbbb 100644
> --- a/arch/powerpc/Kconfig
> +++ b/arch/powerpc/Kconfig
> @@ -629,6 +629,9 @@ config ZONE_DMA
> bool
> default y
>
> +config ZONE_DMA32
> + def_bool (PPC64 && PPC_FSL_BOOK3E)
> +
> config NEED_DMA_MAP_STATE
> def_bool (PPC64 || NOT_COHERENT_CACHE)
>
> diff --git a/arch/powerpc/kernel/dma.c b/arch/powerpc/kernel/dma.c
> index 355b9d8..cbf5ac1 100644
> --- a/arch/powerpc/kernel/dma.c
> +++ b/arch/powerpc/kernel/dma.c
> @@ -41,9 +41,24 @@ void *dma_direct_alloc_coherent(struct device *dev, size_t
> size,
> #else
> struct page *page;
> int node = dev_to_node(dev);
> +#ifdef CONFIG_ZONE_DMA32
> + phys_addr_t top_ram_pfn = memblock_end_of_DRAM();
>
> + /*
> + * check for crappy device which has dma_mask < ZONE_DMA, and
> + * we are not going to support it, just warn and fail.
> + */
> + if (*dev->dma_mask < DMA_BIT_MASK(31)) {
> + dev_err(dev, "Unsupported dma_mask 0x%llx\n", *dev->dma_mask);
> + return NULL;
> + }
> /* ignore region specifiers */
> + flag &= ~(__GFP_HIGHMEM | __GFP_DMA | __GFP_DMA32);
> + if (*dev->dma_mask < top_ram_pfn - 1)
> + flag |= __GFP_DMA32;
> +#else
> flag &= ~(__GFP_HIGHMEM);
> +#endif
>
> page = alloc_pages_node(node, flag, get_order(size));
> if (page == NULL)
> diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
> index baaafde..2a11e49 100644
> --- a/arch/powerpc/mm/mem.c
> +++ b/arch/powerpc/mm/mem.c
> @@ -280,6 +280,10 @@ void __init paging_init(void)
> #ifdef CONFIG_HIGHMEM
> max_zone_pfns[ZONE_DMA] = lowmem_end_addr >> PAGE_SHIFT;
> max_zone_pfns[ZONE_HIGHMEM] = top_of_ram >> PAGE_SHIFT;
> +#elif defined CONFIG_ZONE_DMA32
> + max_zone_pfns[ZONE_DMA32] = min_t(phys_addr_t, top_of_ram,
> + 1ull << 31) >> PAGE_SHIFT;
> + max_zone_pfns[ZONE_NORMAL] = top_of_ram >> PAGE_SHIFT;
> #else
> max_zone_pfns[ZONE_DMA] = top_of_ram >> PAGE_SHIFT;
> #endif
> --
> 1.6.4
>
>
> _______________________________________________
> Linuxppc-dev mailing list
> Linuxppc-dev@lists.ozlabs.org
> https://lists.ozlabs.org/listinfo/linuxppc-dev
_______________________________________________
Linuxppc-dev mailing list
Linuxppc-dev@lists.ozlabs.org
https://lists.ozlabs.org/listinfo/linuxppc-dev
