From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id AECA2B6F8C for ; Thu, 13 Oct 2011 03:08:25 +1100 (EST) Subject: Re: [PATCH] UIO: Allow a UIO driver to override the default pgprot when we mmap Mime-Version: 1.0 (Apple Message framework v1244.3) Content-Type: text/plain; charset=us-ascii From: Kumar Gala In-Reply-To: <20111012153536.GC21852@local> Date: Wed, 12 Oct 2011 11:08:20 -0500 Message-Id: References: <1318430616-20351-1-git-send-email-galak@kernel.crashing.org> <20111012153536.GC21852@local> To: "Hans J. Koch" Cc: linuxppc-dev@ozlabs.org, 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 Oct 12, 2011, at 10:35 AM, Hans J. Koch wrote: > 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. >=20 > For what devices? Can you give a real world usecase where this is = needed? >=20 > Thanks, > Hans In the Freescale Networking devices we have a coherent memory interface = to our HW queuing system. In that case we want to change the pgprot() = to be cache-able instead of non-cached. - k >=20 >> Provide a means for the >> kernel side UIO driver to override the flags without having to >> implement its own full mmap callback. >>=20 >> Signed-off-by: Kumar Gala >> --- >> drivers/uio/uio.c | 6 +++++- >> include/linux/uio_driver.h | 2 ++ >> 2 files changed, 7 insertions(+), 1 deletions(-) >>=20 >> 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) >>=20 >> vma->vm_flags |=3D VM_IO | VM_RESERVED; >>=20 >> - vma->vm_page_prot =3D pgprot_noncached(vma->vm_page_prot); >> + if (idev->info->mem[mi].set_pgprot) >> + vma->vm_page_prot =3D >> + = idev->info->mem[mi].set_pgprot(vma->vm_page_prot); >> + else >> + vma->vm_page_prot =3D = pgprot_noncached(vma->vm_page_prot); >>=20 >> 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); >> }; >>=20 >> #define MAX_UIO_MAPS 5 >> --=20 >> 1.7.3.4 >>=20 >>=20