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    SubjectSATA_SIL on IXP425 workaround
    I'm trying to add a workaround for IXP4xx CPUs to SATA SIL driver. The
    problem is that IXP4xx CPUs (Intel's XScale (ARM) network-oriented
    processors) are unable to perform 8 and 16-bit read from PCI MMIO, they
    can only do a full 32-bit readl(); SIL chips respond to that with PCI
    abort. The workaround is to use 8 and 16-bit regular IO reads (inb/inw)
    instead (MMIO write is not a problem).

    For SIL3x12 the workaround is simple (attached) and it works on my 3512.
    I'm not sure about 3114 (the 4-port chip) - the PIO BARs have TF, CTL
    and BWDMA registers which are common to channels 0 and 2, and (the other
    set) to channels 1 and 3. Channel selection is done with bit 4 of
    device/head TF register, this is similar (same?) as PATA master/slave.
    Does that mean that I can simply treat channel 0 as PRI master, ch#2 as
    PRI slave, ch#1 as SEC master and ch#3 as SEC slave, and the SFF code
    will select the right device correctly? Does it need additional code?
    I don't have anything based on 3114.

    Note: the large PRD is not a problem here, the transfer can be started
    by MMIO write. Only reads are an issue.

    --- a/drivers/ata/sata_sil.c
    +++ b/drivers/ata/sata_sil.c
    @@ -757,7 +757,12 @@ static int sil_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
    if (rc)
    return rc;

    +#ifdef CONFIG_ARCH_IXP4XX
    + /* We need all 6 regions on IXP4xx */
    + rc = pcim_iomap_regions(pdev, 0x3F, DRV_NAME);
    rc = pcim_iomap_regions(pdev, 1 << SIL_MMIO_BAR, DRV_NAME);
    if (rc == -EBUSY)
    if (rc)
    @@ -777,10 +782,18 @@ static int sil_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
    struct ata_port *ap = host->ports[i];
    struct ata_ioports *ioaddr = &ap->ioaddr;

    +#ifdef CONFIG_ARCH_IXP4XX
    + /* IXP4xx CPUs can't perform 8 and 16-bit MMIO reads,
    + use normal IO from/to regions 0-5 instead */
    + ioaddr->cmd_addr = host->iomap[i * 2];
    + ioaddr->altstatus_addr = host->iomap[1 + i * 2] + 2;
    + ioaddr->bmdma_addr = host->iomap[4] + sil_port[i].bmdma;
    ioaddr->cmd_addr = mmio_base + sil_port[i].tf;
    - ioaddr->altstatus_addr =
    - ioaddr->ctl_addr = mmio_base + sil_port[i].ctl;
    + ioaddr->altstatus_addr = mmio_base + sil_port[i].ctl;
    ioaddr->bmdma_addr = mmio_base + sil_port[i].bmdma;
    + ioaddr->ctl_addr = mmio_base + sil_port[i].ctl;
    ioaddr->scr_addr = mmio_base + sil_port[i].scr;

    Krzysztof Halasa

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      Last update: 2009-11-09 18:33    [W:0.020 / U:30.576 seconds]
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