From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from www.hansjkoch.de (www.hansjkoch.de [178.63.77.200]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id 65E20B6F85 for ; Thu, 13 Oct 2011 03:17:56 +1100 (EST) Date: Wed, 12 Oct 2011 17:35:36 +0200 From: "Hans J. Koch" To: Kumar Gala Subject: Re: [PATCH] UIO: Allow a UIO driver to override the default pgprot when we mmap Message-ID: <20111012153536.GC21852@local> References: <1318430616-20351-1-git-send-email-galak@kernel.crashing.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <1318430616-20351-1-git-send-email-galak@kernel.crashing.org> Cc: linuxppc-dev@ozlabs.org, hjk@hansjkoch.de, gregkh@suse.de, linux-kernel@vger.kernel.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Wed, Oct 12, 2011 at 09:43:36AM -0500, Kumar Gala wrote: > For some devices the default behavior of pgprot_noncached is not > the correct flags for the address space. For what devices? Can you give a real world usecase where this is needed? Thanks, Hans > Provide a means for the > kernel side UIO driver to override the flags without having to > implement its own full mmap callback. > > Signed-off-by: Kumar Gala > --- > drivers/uio/uio.c | 6 +++++- > include/linux/uio_driver.h | 2 ++ > 2 files changed, 7 insertions(+), 1 deletions(-) > > diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c > index d2efe82..88f4444 100644 > --- a/drivers/uio/uio.c > +++ b/drivers/uio/uio.c > @@ -656,7 +656,11 @@ static int uio_mmap_physical(struct vm_area_struct *vma) > > vma->vm_flags |= VM_IO | VM_RESERVED; > > - vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot); > + if (idev->info->mem[mi].set_pgprot) > + vma->vm_page_prot = > + idev->info->mem[mi].set_pgprot(vma->vm_page_prot); > + else > + vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot); > > return remap_pfn_range(vma, > vma->vm_start, > diff --git a/include/linux/uio_driver.h b/include/linux/uio_driver.h > index 665517c..4c618cd 100644 > --- a/include/linux/uio_driver.h > +++ b/include/linux/uio_driver.h > @@ -28,6 +28,7 @@ struct uio_map; > * @memtype: type of memory addr points to > * @internal_addr: ioremap-ped version of addr, for driver internal use > * @map: for use by the UIO core only. > + * @set_pgprot: allow driver to override default(noncached) pgprot > */ > struct uio_mem { > const char *name; > @@ -36,6 +37,7 @@ struct uio_mem { > int memtype; > void __iomem *internal_addr; > struct uio_map *map; > + pgprot_t (*set_pgprot)(pgprot_t prot); > }; > > #define MAX_UIO_MAPS 5 > -- > 1.7.3.4 > >