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Subject[PATCH] PNP: set the pnp_card dma_mask for use by ISAPnP cards

From 801c13fb3e8564221a1fb21892dbe13add3d7cea Mon Sep 17 00:00:00 2001
From: Rene Herman <>
Date: Fri, 30 May 2008 23:10:23 +0200
Subject: [PATCH] PNP: set the pnp_card dma_mask for use by ISAPnP cards.

dma_alloc_coherent() on x86 currently takes a passed in NULL device
pointer to mean that it should allocate an ISA compatible (24-bit)
buffer which is a bit of a hack.

The ALSA ISA drivers are the main consumers of this but have a struct
device in fact readily available.

For the PnP drivers, the specific pnp_dev->dev device pointer is not
always available at the right time so for now we want to pass the
pnp_card->dev instead which is always available. Set its dma_mask in
preparation for doing so.

This does not fix a current bug -- 2.6.26-rc1 stumbled over the NULL
hack in dma_alloc_coherent() but this has already been fixed in commit
4a367f3a9dbf2e7ffcee4702203479809236ee6e by Takashi Iwai.

Signed-off-by: Rene Herman <>
Acked-by: Bjorn Helgaas <>
Cc: Takashi Iwai <>
Cc: Alan Cox <>
drivers/pnp/card.c | 4 ++++
1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/drivers/pnp/card.c b/drivers/pnp/card.c
index a762a41..b00ef10 100644
--- a/drivers/pnp/card.c
+++ b/drivers/pnp/card.c
@@ -8,6 +8,7 @@
#include <linux/ctype.h>
#include <linux/slab.h>
#include <linux/pnp.h>
+#include <linux/dma-mapping.h>
#include "base.h"

@@ -167,6 +168,9 @@ struct pnp_card *pnp_alloc_card(struct pnp_protocol *protocol, int id, char *pnp
sprintf(card->dev.bus_id, "%02x:%02x", card->protocol->number,

+ card->dev.coherent_dma_mask = DMA_24BIT_MASK;
+ card->dev.dma_mask = &card->dev.coherent_dma_mask;
dev_id = pnp_add_card_id(card, pnpid);
if (!dev_id) {
 \ /
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