Messages in this thread | | | From | Geert Uytterhoeven <> | Date | Mon, 23 Jul 2018 10:49:39 +0200 | Subject | Re: [PATCH 4/5] sh: split arch/sh/mm/consistent.c |
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Hi Jacopo,
On Mon, Jul 23, 2018 at 10:42 AM jacopo mondi <jacopo@jmondi.org> wrote: > 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@lst.de>
> > --- /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...
> > - *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);
Doesn't look right to me, neither.
No complaints for 0day? My gcc says:
error: statement with no effect [-Werror=unused-value]
Gr{oetje,eeting}s,
Geert
-- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
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