Re: [PATCH] drivers: rtl818x: request DMA-able memory

From: John W. Linville
Date: Mon Oct 25 2010 - 09:45:43 EST


On Sun, Oct 24, 2010 at 10:32:07PM +0200, 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@xxxxxxxxxx>
> ---
> 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;

Are you sure about this? Are there USB controllers out there with
the ISA 16MB limitation for DMA?

John
--
John W. Linville Someday the world will need a hero, and you
linville@xxxxxxxxxxxxx might be all we have. Be ready.
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