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SubjectRe: [PATCH] drivers: rtl818x: request DMA-able memory
On Mon, Oct 25, 2010 at 10:22:32AM -0400, John W. Linville wrote:
> On Mon, Oct 25, 2010 at 03:11:22PM +0100, Hin-Tak Leung wrote:
> >
> >
> > Larry Finger wrote:
> > >On 10/24/2010 03:32 PM, Serafeim Zanikolas wrote:
> > >>Despite the indicated intention in comment, the kmalloc() call was not
> > >>explicitly requesting memory from ZONE_DMA.
> > >>
> > >>Signed-off-by: Serafeim Zanikolas <sez@debian.org>
> > >>---
> > >> drivers/net/wireless/rtl818x/rtl8187_dev.c | 3 ++-
> > >> 1 files changed, 2 insertions(+), 1 deletions(-)
> > >>
> > >>diff --git a/drivers/net/wireless/rtl818x/rtl8187_dev.c b/drivers/net/wireless/rtl818x/rtl8187_dev.c
> > >>index 38fa824..771794d 100644
> > >>--- a/drivers/net/wireless/rtl818x/rtl8187_dev.c
> > >>+++ b/drivers/net/wireless/rtl818x/rtl8187_dev.c
> > >>@@ -1343,7 +1343,8 @@ static int __devinit rtl8187_probe(struct usb_interface *intf,
> > >> priv->is_rtl8187b = (id->driver_info == DEVICE_RTL8187B);
> > >> /* allocate "DMA aware" buffer for register accesses */
> > >>- priv->io_dmabuf = kmalloc(sizeof(*priv->io_dmabuf), GFP_KERNEL);
> > >>+ priv->io_dmabuf = kmalloc(sizeof(*priv->io_dmabuf),
> > >>+ GFP_DMA | GFP_KERNEL);
> > >> if (!priv->io_dmabuf) {
> > >> err = -ENOMEM;
> > >> goto err_free_dev;
> > >
> > >ACK.
> > >
> > >Larry
> >
> > Acked-by: Hin-Tak Leung <htl10@users.sourceforge.net>
> >
> > I had a quick look for similiar constructs and AFAIK only the
> > b43/b43legacy drivers uses DMA buffers. Seems to be a rare practice.
> > Is that something we should or should not do?
>
> It doesn't mean what you think it means. It is a relic of the past,
> used to indicate memory below 16MB so that ISA devices could do DMA.

Right. Sorry for the noise.

-S


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