--- Tejun Heo <htejun@xxxxxxxxx> wrote:
> Hello,
Hello,
> It just seems sb600 claims that it can do DMA above 4G while it actually
> can't. Can you test the attached patch?
Makes sense now. Gladly check the patch. Checking ...
Great news: everything just works without any parameters :-)). True genious.
With your patch, with 4 GB of RAM, all SATA drives are detected & working
normally. For the record dmesg is attached.
There's always a catch isn't it? Now no DMA over 32 bit memory space for SATA,
right? CPU will have to work harder, I presume. Perhaps putting more pressure.
While with 4 GB that might not be a problem, perhaps when I upgrade it to over
4 GB, it might be?? I see, even now, because a chunk of 512 MB is mapped over
4 GB (starting at 0x100000000), those are no good for the SATA's DMA access.
If so, too sad :-(.
> Thanks.
Thank you.
(I'll leave the patch for the poor souls stumble upon these emails some far
future :-))
PS: if this turns out to a hardware limitation, then perhaps may I request
this patch in better form (as not to impact on other ahci users) find its way
to mainstream? Even to -stable if I'm lucky, such that Fedora 7 etc. might
work out of the box for poor souls (not counting me; I'm used to quirky
things) trying out Linux on this chipset.
> --
> tejun
> > ---
> drivers/ata/ahci.c | 10 +++++++++-
> 1 file changed, 9 insertions(+), 1 deletion(-)
>
> Index: tree0/drivers/ata/ahci.c
> ===================================================================
> --- tree0.orig/drivers/ata/ahci.c
> +++ tree0/drivers/ata/ahci.c
> @@ -170,6 +170,7 @@ enum {
> AHCI_FLAG_IGN_IRQ_IF_ERR = (1 << 25), /* ignore IRQ_IF_ERR */
> AHCI_FLAG_HONOR_PI = (1 << 26), /* honor PORTS_IMPL */
> AHCI_FLAG_IGN_SERR_INTERNAL = (1 << 27), /* ignore SERR_INTERNAL */
> + AHCI_FLAG_32BIT_ONLY = (1 << 28), /* force 32bit */
> };
>
> struct ahci_cmd_hdr {
> @@ -370,7 +371,8 @@ static const struct ata_port_info ahci_p
> .flags = ATA_FLAG_SATA | ATA_FLAG_NO_LEGACY |
> ATA_FLAG_MMIO | ATA_FLAG_PIO_DMA |
> ATA_FLAG_SKIP_D2H_BSY |
> - AHCI_FLAG_IGN_SERR_INTERNAL,
> + AHCI_FLAG_IGN_SERR_INTERNAL |
> + AHCI_FLAG_32BIT_ONLY,
> .pio_mask = 0x1f, /* pio0-4 */
> .udma_mask = 0x7f, /* udma0-6 ; FIXME */
> .port_ops = &ahci_ops,
> @@ -1579,6 +1581,12 @@ static int ahci_host_init(struct ata_pro
> probe_ent->n_ports = cap_n_ports;
>
> using_dac = hpriv->cap & HOST_CAP_64;
> + if (using_dac && (probe_ent->port_flags & AHCI_FLAG_32BIT_ONLY)) {
> + dev_printk(KERN_INFO, &pdev->dev,
> + "controller can't do 64bit DMA, forcing 32bit\n");
> + using_dac = 0;
> + }
> +
> if (using_dac &&
> !pci_set_dma_mask(pdev, DMA_64BIT_MASK)) {
> rc = pci_set_consistent_dma_mask(pdev, DMA_64BIT_MASK);
>
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