From: Sherry Sun <sherry.sun@nxp.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: "sudeep.dutt@intel.com" <sudeep.dutt@intel.com>,
"ashutosh.dixit@intel.com" <ashutosh.dixit@intel.com>,
"arnd@arndb.de" <arnd@arndb.de>,
"gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
"kishon@ti.com" <kishon@ti.com>,
"lorenzo.pieralisi@arm.com" <lorenzo.pieralisi@arm.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
dl-linux-imx <linux-imx@nxp.com>
Subject: RE: [PATCH V2 4/4] misc: vop: mapping kernel memory to user space as noncached
Date: Tue, 29 Sep 2020 13:12:43 +0000 [thread overview]
Message-ID: <VI1PR04MB4960D01FB5508589D586AE5792320@VI1PR04MB4960.eurprd04.prod.outlook.com> (raw)
In-Reply-To: <20200929102833.GD7784@infradead.org>
Hi Christoph,
> On Tue, Sep 29, 2020 at 04:44:25PM +0800, Sherry Sun wrote:
> > Mapping kernel space memory to user space as noncached, since user
> > space need check the updates of avail_idx and device page flags timely.
> >
> > Signed-off-by: Joakim Zhang <qiangqing.zhang@nxp.com>
> > Signed-off-by: Sherry Sun <sherry.sun@nxp.com>
> > ---
> > drivers/misc/mic/vop/vop_vringh.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/misc/mic/vop/vop_vringh.c
> > b/drivers/misc/mic/vop/vop_vringh.c
> > index 4d5feb39aeb7..6e193bd64ef1 100644
> > --- a/drivers/misc/mic/vop/vop_vringh.c
> > +++ b/drivers/misc/mic/vop/vop_vringh.c
> > @@ -1057,7 +1057,7 @@ static int vop_mmap(struct file *f, struct
> vm_area_struct *vma)
> > }
> > err = remap_pfn_range(vma, vma->vm_start + offset,
> > pa >> PAGE_SHIFT, size,
> > - vma->vm_page_prot);
> > + pgprot_noncached(vma->vm_page_prot));
>
> You can't call remap_pfn_range on memory returned from
> dma_alloc_coherent (which btw is not marked uncached on many platforms).
>
> You need to use the dma_mmap_coherent helper instead. And this also
> needs to go into the first patch.
Okay, will try to use dma_mmap_coherent api in V3. Thanks.
Regards
Sherry
next prev parent reply other threads:[~2020-09-29 13:12 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-29 8:44 [PATCH V2 0/4] Change vring space from nomal memory to dma coherent memory Sherry Sun
2020-09-29 8:44 ` [PATCH V2 1/4] misc: vop: change the way of allocating vring Sherry Sun
2020-09-29 10:23 ` Christoph Hellwig
2020-09-29 13:02 ` Sherry Sun
2020-09-29 8:44 ` [PATCH V2 2/4] misc: vop: do not allocate and reassign the used ring Sherry Sun
2020-09-29 10:24 ` Christoph Hellwig
2020-09-29 13:02 ` Sherry Sun
2020-09-29 14:28 ` David Laight
2020-09-29 8:44 ` [PATCH V2 3/4] misc: vop: simply return the saved dma address instead of virt_to_phys Sherry Sun
2020-09-29 10:26 ` Christoph Hellwig
2020-09-29 13:10 ` Sherry Sun
2020-09-29 18:11 ` Christoph Hellwig
2020-09-30 7:30 ` Sherry Sun
2020-10-05 13:42 ` Christoph Hellwig
2020-09-29 8:44 ` [PATCH V2 4/4] misc: vop: mapping kernel memory to user space as noncached Sherry Sun
2020-09-29 10:28 ` Christoph Hellwig
2020-09-29 13:12 ` Sherry Sun [this message]
2020-09-29 15:39 ` David Laight
2020-10-13 2:02 ` Sherry Sun
2020-10-20 1:33 ` Sherry Sun
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