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    SubjectRe: [PATCH] Re: More than 2Gb problem (dvb related) ?
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    On Sat, 2007-04-28 at 18:17 +0100, Jon Burgess wrote:
    > On Fri, 2007-04-27 at 18:06 -0400, Lee Revell wrote:
    > > On 4/27/07, Jon Burgess <jburgess777@googlemail.com> wrote:
    > > > Interesting - I see similar symptoms after upgrading my PC:
    > > > * old PC was AMD Athlon 64 3000 w/ 2GB of RAM which had no issues
    > > > * new PC is a Intel Core 2 Duo w/ 4GB of RAM and fails in the way you
    > > > describe.
    > >
    > > Driver using an incorrect DMA mask?
    > >
    > > Lee
    >
    > It appears the problem is that the driver is using streamed PCI and
    > needs to explicitly sync the data otherwise it breaks when the SWIOTLB
    > is in use. A call to pci_unmap_sg() was missing too.
    >
    > This patch is against the current v4l-dvb HG tree.
    >
    > I've only tested the change with a budget-ci card.
    >
    > Jon
    >
    > Signed-off-by: Jon Burgess <jburgess777@googlemail.com>

    While the above patch works, it seems the underlying causes is that
    vmalloc_32() is providing memory above 4Gb on x86-64 which is not what
    the driver expects. This same issue came up a few weeks ago with regards
    to DRM on radeon http://lkml.org/lkml/2007/4/1/257

    Andi Kleen included a patch to ensure vmalloc_32() returns memory <4Gb
    in a patch which is currently in -mm
    http://kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.21-rc7/2.6.21-rc7-mm2/broken-out/x86_64-mm-vmalloc-32.patch

    With this patch applied the current driver appears to work OK.

    Attached is a smaller patch against v4l-dvb which just adds the missing
    pci_unmap_sg() call.

    Jon

    Signed-off-by: Jon Burgess <jburgess777@googlemail.com>
    diff -r a8b2a0738f4e linux/drivers/media/common/saa7146_core.c
    --- a/linux/drivers/media/common/saa7146_core.c Thu Apr 19 17:07:37 2007 -0300
    +++ b/linux/drivers/media/common/saa7146_core.c Sat Apr 28 20:55:30 2007 +0100
    @@ -152,6 +152,7 @@ char *saa7146_vmalloc_build_pgtable(stru
    return NULL;
    }

    + pt->nents = pages;
    slen = pci_map_sg(pci,pt->slist,pages,PCI_DMA_FROMDEVICE);
    if (0 != saa7146_pgtable_build_single(pci, pt, pt->slist, slen)) {
    return NULL;
    @@ -165,6 +166,7 @@ void saa7146_pgtable_free(struct pci_dev
    if (NULL == pt->cpu)
    return;
    pci_free_consistent(pci, pt->size, pt->cpu, pt->dma);
    + pci_unmap_sg(pci, pt->slist, pt->nents, PCI_DMA_FROMDEVICE);
    pt->cpu = NULL;
    kfree(pt->slist);
    pt->slist = NULL;
    diff -r a8b2a0738f4e linux/include/media/saa7146.h
    --- a/linux/include/media/saa7146.h Thu Apr 19 17:07:37 2007 -0300
    +++ b/linux/include/media/saa7146.h Sat Apr 28 18:06:47 2007 +0100
    @@ -70,6 +70,7 @@ struct saa7146_pgtable {
    unsigned long offset;
    /* used for custom pagetables (used for example by budget dvb cards) */
    struct scatterlist *slist;
    + int nents;
    };

    struct saa7146_pci_extension_data {
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      Last update: 2007-04-28 22:19    [W:0.025 / U:2.740 seconds]
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