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Date: Mon, 23 Jul 2018 10:42:07 +0200
From: jacopo mondi <jacopo@...ndi.org>
To: Christoph Hellwig <hch@....de>
Cc: Yoshinori Sato <ysato@...rs.sourceforge.jp>,
Rich Felker <dalias@...c.org>,
Jacopo Mondi <jacopo+renesas@...ndi.org>,
Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>,
linux-sh@...r.kernel.org, iommu@...ts.linux-foundation.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/5] sh: split arch/sh/mm/consistent.c
Hi Christoph,
I have a single comment on something I noticed which might be an
implementation bug. On the overall patch architecture, it's very hard
for me to provide a valuable opinion as it's all relatively new for me
here :)
On Thu, Jul 19, 2018 at 06:05:15AM -0700, Christoph Hellwig wrote:
> Half of the file just contains platform device memory setup code which
> is required for all builds, and half contains helpers for dma coherent
> allocation, which is only needed if CONFIG_DMA_NONCOHERENT is enabled.
>
> Signed-off-by: Christoph Hellwig <hch@....de>
> ---
> arch/sh/kernel/Makefile | 2 +-
> arch/sh/kernel/dma-coherent.c | 85 +++++++++++++++++++++++++++++++++++
> arch/sh/mm/consistent.c | 80 ---------------------------------
> 3 files changed, 86 insertions(+), 81 deletions(-)
> create mode 100644 arch/sh/kernel/dma-coherent.c
>
> diff --git a/arch/sh/kernel/Makefile b/arch/sh/kernel/Makefile
> index cb5f1bfb52de..d5ddb64bfffe 100644
> --- a/arch/sh/kernel/Makefile
> +++ b/arch/sh/kernel/Makefile
> @@ -45,7 +45,7 @@ obj-$(CONFIG_DUMP_CODE) += disassemble.o
> obj-$(CONFIG_HIBERNATION) += swsusp.o
> obj-$(CONFIG_DWARF_UNWINDER) += dwarf.o
> obj-$(CONFIG_PERF_EVENTS) += perf_event.o perf_callchain.o
> -obj-$(CONFIG_DMA_NONCOHERENT) += dma-nommu.o
> +obj-$(CONFIG_DMA_NONCOHERENT) += dma-nommu.o dma-coherent.o
> obj-$(CONFIG_HAVE_HW_BREAKPOINT) += hw_breakpoint.o
>
> ccflags-y := -Werror
> diff --git a/arch/sh/kernel/dma-coherent.c b/arch/sh/kernel/dma-coherent.c
> new file mode 100644
> index 000000000000..0e7720b5d495
> --- /dev/null
> +++ b/arch/sh/kernel/dma-coherent.c
> @@ -0,0 +1,85 @@
> +/*
> + * Copyright (C) 2004 - 2007 Paul Mundt
> + *
> + * This file is subject to the terms and conditions of the GNU General Public
> + * License. See the file "COPYING" in the main directory of this archive
> + * for more details.
> + */
> +#include <linux/mm.h>
> +#include <linux/init.h>
> +#include <linux/dma-mapping.h>
> +#include <linux/module.h>
> +#include <asm/cacheflush.h>
> +#include <asm/addrspace.h>
> +
> +void *dma_generic_alloc_coherent(struct device *dev, size_t size,
> + dma_addr_t *dma_handle, gfp_t gfp,
> + unsigned long attrs)
> +{
> + void *ret, *ret_nocache;
> + int order = get_order(size);
> +
> + gfp |= __GFP_ZERO;
> +
> + ret = (void *)__get_free_pages(gfp, order);
> + if (!ret)
> + return NULL;
> +
> + /*
> + * Pages from the page allocator may have data present in
> + * cache. So flush the cache before using uncached memory.
> + */
> + sh_sync_dma_for_device(ret, size, DMA_BIDIRECTIONAL);
> +
> + ret_nocache = (void __force *)ioremap_nocache(virt_to_phys(ret), size);
> + if (!ret_nocache) {
> + free_pages((unsigned long)ret, order);
> + return NULL;
> + }
> +
> + split_page(pfn_to_page(virt_to_phys(ret) >> PAGE_SHIFT), order);
> +
> + *dma_handle = virt_to_phys(ret);
> + if (!WARN_ON(!dev))
> + *dma_handle - PFN_PHYS(dev->dma_pfn_offset);
I guess this comes from below...
> +
> + return ret_nocache;
> +}
> +
> +void dma_generic_free_coherent(struct device *dev, size_t size,
> + void *vaddr, dma_addr_t dma_handle,
> + unsigned long attrs)
> +{
> + int order = get_order(size);
> + unsigned long pfn = (dma_handle >> PAGE_SHIFT);
> + int k;
> +
> + if (!WARN_ON(!dev))
> + pfn + dev->dma_pfn_offset;
> +
> + for (k = 0; k < (1 << order); k++)
> + __free_pages(pfn_to_page(pfn + k), 0);
> +
> + iounmap(vaddr);
> +}
> +
> +void sh_sync_dma_for_device(void *vaddr, size_t size,
> + enum dma_data_direction direction)
> +{
> + void *addr = sh_cacheop_vaddr(vaddr);
> +
> + switch (direction) {
> + case DMA_FROM_DEVICE: /* invalidate only */
> + __flush_invalidate_region(addr, size);
> + break;
> + case DMA_TO_DEVICE: /* writeback only */
> + __flush_wback_region(addr, size);
> + break;
> + case DMA_BIDIRECTIONAL: /* writeback and invalidate */
> + __flush_purge_region(addr, size);
> + break;
> + default:
> + BUG();
> + }
> +}
> +EXPORT_SYMBOL(sh_sync_dma_for_device);
> diff --git a/arch/sh/mm/consistent.c b/arch/sh/mm/consistent.c
> index 1622ae6b9dbd..792f36129062 100644
> --- a/arch/sh/mm/consistent.c
> +++ b/arch/sh/mm/consistent.c
> @@ -1,10 +1,6 @@
> /*
> - * arch/sh/mm/consistent.c
> - *
> * Copyright (C) 2004 - 2007 Paul Mundt
> *
> - * Declared coherent memory functions based on arch/x86/kernel/pci-dma_32.c
> - *
> * This file is subject to the terms and conditions of the GNU General Public
> * License. See the file "COPYING" in the main directory of this archive
> * for more details.
> @@ -13,83 +9,7 @@
> #include <linux/init.h>
> #include <linux/platform_device.h>
> #include <linux/dma-mapping.h>
> -#include <linux/dma-debug.h>
> #include <linux/io.h>
> -#include <linux/module.h>
> -#include <linux/gfp.h>
> -#include <asm/cacheflush.h>
> -#include <asm/addrspace.h>
> -
> -void *dma_generic_alloc_coherent(struct device *dev, size_t size,
> - dma_addr_t *dma_handle, gfp_t gfp,
> - unsigned long attrs)
> -{
> - void *ret, *ret_nocache;
> - int order = get_order(size);
> -
> - gfp |= __GFP_ZERO;
> -
> - ret = (void *)__get_free_pages(gfp, order);
> - if (!ret)
> - return NULL;
> -
> - /*
> - * Pages from the page allocator may have data present in
> - * cache. So flush the cache before using uncached memory.
> - */
> - sh_sync_dma_for_device(ret, size, DMA_BIDIRECTIONAL);
> -
> - ret_nocache = (void __force *)ioremap_nocache(virt_to_phys(ret), size);
> - if (!ret_nocache) {
> - free_pages((unsigned long)ret, order);
> - return NULL;
> - }
> -
> - split_page(pfn_to_page(virt_to_phys(ret) >> PAGE_SHIFT), order);
> -
> - *dma_handle = virt_to_phys(ret);
> - if (!WARN_ON(!dev))
> - *dma_handle -= PFN_PHYS(dev->dma_pfn_offset);
... here
Is the s/-=/- intended?
Snippets copied here below:
> + *dma_handle = virt_to_phys(ret);
> + if (!WARN_ON(!dev))
> + *dma_handle - PFN_PHYS(dev->dma_pfn_offset);
vs
> - *dma_handle = virt_to_phys(ret);
> - if (!WARN_ON(!dev))
> - *dma_handle -= PFN_PHYS(dev->dma_pfn_offset);
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