From: Jaroslav Kysela <perex@suse.cz>
To: Jeff Garzik <jgarzik@pobox.com>
Cc: LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] ALSA update [6/10] - 2002/07/20
Date: Sun, 29 Sep 2002 22:34:51 +0200 (CEST) [thread overview]
Message-ID: <Pine.LNX.4.33.0209292230500.591-100000@pnote.perex-int.cz> (raw)
In-Reply-To: <3D9759FF.2050802@pobox.com>
On Sun, 29 Sep 2002, Jeff Garzik wrote:
> Jaroslav Kysela wrote:
> > On 29 Sep 2002, Arjan van de Ven wrote:
> >>what is wrong with the PCI DMA API that makes ALSA wants a private
> >>interface/implementation ?
> >
> >
> > These lines (i386 arch):
> >
> > if (hwdev == NULL || ((u32)hwdev->dma_mask != 0xffffffff))
> > gfp |= GFP_DMA;
> > ret = (void *)__get_free_pages(gfp, get_order(size));
> >
> > Note that some of soundcards have various PCI DMA transfer limits
> > (dma_mask is not set to use full 32-bits). In this case, restricting this
> > hardware to allocate these buffers in first 16MB is not a very good idea.
> > Thus, we have own hacks to allocate memory in whole hardware area.
>
> It sounds like it would be reasonable to fix the ia32 arch code, would
> it not?
We have simple method in our hack:
- try to allocate memory anywhere
- try to allocate memory with GFP DMA if first step fails
Here is updated pci-dma.c code for comments:
===== pci-dma.c 1.8 vs edited =====
--- 1.8/arch/i386/kernel/pci-dma.c Thu May 9 19:24:12 2002
+++ edited/pci-dma.c Sun Sep 29 22:26:46 2002
@@ -19,14 +19,24 @@
void *ret;
int gfp = GFP_ATOMIC;
- if (hwdev == NULL || ((u32)hwdev->dma_mask != 0xffffffff))
+ if (hwdev == NULL || (u32)hwdev->dma_mask <= 0x00ffffff)
gfp |= GFP_DMA;
ret = (void *)__get_free_pages(gfp, get_order(size));
- if (ret != NULL) {
- memset(ret, 0, size);
- *dma_handle = virt_to_phys(ret);
+ if (ret == NULL)
+ return NULL;
+
+ /* try to allocate area in first 16MB memory */
+ if ((gfp & GFP_DMA) == 0 && (u32)hwdev->dma_mask != 0xffffffff &&
+ ((virt_to_phys(ret) + size - 1) & ~(u32)hwdev->dma_mask) != 0) {
+ free_pages(ret, get_order(size));
+ ret = (void *)__get_free_pages(gfp | GFP_DMA, get_order(size));
+ if (ret == NULL)
+ return NULL;
}
+
+ memset(ret, 0, size);
+ *dma_handle = virt_to_phys(ret);
return ret;
}
Jaroslav
-----
Jaroslav Kysela <perex@suse.cz>
Linux Kernel Sound Maintainer
ALSA Project http://www.alsa-project.org
SuSE Linux http://www.suse.com
next prev parent reply other threads:[~2002-09-29 20:30 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-09-29 18:51 [PATCH] ALSA update [6/10] - 2002/07/20 Jaroslav Kysela
2002-09-29 19:12 ` Arjan van de Ven
2002-09-29 19:28 ` Jaroslav Kysela
2002-09-29 19:52 ` Jeff Garzik
2002-09-29 20:34 ` Jaroslav Kysela [this message]
2002-09-29 21:19 ` Alan Cox
2002-09-30 0:53 ` David S. Miller
2002-09-30 12:54 ` Alan Cox
2002-09-30 16:17 ` Jaroslav Kysela
2002-09-30 20:33 ` David S. Miller
2002-09-30 0:22 ` David S. Miller
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