Issues with AHCI and AMD SB700

[Paul Menzel]

Dear SeaBIOS folks,

Timothy Pearson submitted the change below [1] to the coreboot
repository.

```
ommit 14ebf951e41c085aa2f8420fcf7452dc5761514e
Author: Timothy Pearson 
Date:   Sun Jun 21 16:27:03 2015 -0500

src/southbridge/amd/sb700: Reset SATA controller in AHCI mode during startup

In AHCI mode SeaBIOS randomly fails to detect disks (AHCI timeouts),
    with the probability of a failure increasing with the number of disks
    connected to the controller.  Resetting the SATA controller appears to
    show the true state of the underlying hardware, allowing the drive
    detection code to attempt link renegotiation as needed.

Change-Id: Ib1f7c5f830a0cdba41cb6f5b05d759adee5ce369
    Signed-off-by: Timothy Pearson 
    Reviewed-on: http://review.coreboot.org/11998
    Tested-by: Raptor Engineering Automated Test Stand 
    Reviewed-by: Stefan Reinauer 
    Tested-by: build bot (Jenkins)

diff --git a/src/southbridge/amd/sb700/sata.c b/src/southbridge/amd/sb700/sata.c
index ae44446..63c07d8 100644
--- a/src/southbridge/amd/sb700/sata.c
+++ b/src/southbridge/amd/sb700/sata.c
@@ -131,6 +131,8 @@ static void sata_init(struct device *dev)
        /* get rev_id */
        rev_id = pci_read_config8(sm_dev, 0x08) - 0x28;

+       printk(BIOS_SPEW, "rev_id=%x\n", rev_id);
+
        if (sata_ahci_mode) {
                /* Enable link latency enhancement on A14 and above */
                if (rev_id >= 0x14) {
@@ -241,6 +243,27 @@ static void sata_init(struct device *dev)
                write32(sata_bar5 + 0xfc, dword);
        }

+       if (sata_ahci_mode) {
+               /* FIXME
+               * SeaBIOS does not know how to spin
+               * up the drives and therefore hangs
+               * in AHCI init if this is enabled...
+               */
+               /* Enable staggered spin-up */
+               dword = read32(sata_bar5 + 0x00);
+#if 0
+               dword |= 0x1 << 27;
+#else
+               dword &= ~(0x1 << 27);
+#endif
+               write32(sata_bar5 + 0x00, dword);
+
+               /* Reset the HBA to avoid stuck drives in SeaBIOS */
+               dword = read32(sata_bar5 + 0x04);
+               dword |= 0x1;
+               write32(sata_bar5 + 0x04, dword);
+       }
+
        /* Write protect Sub-Class Code */
        byte = pci_read_config8(dev, 0x40);
        byte &= ~(1 << 0);
@@ -367,21 +390,21 @@ static void sata_init(struct device *dev)
        }

/* Below is CIM InitSataLateFar */
-       /* Enable interrupts from the HBA  */
-       byte = read8(sata_bar5 + 0x4);
-       byte |= 1 << 1;
-       write8((sata_bar5 + 0x4), byte);
-
        if (!sata_ahci_mode) {
-               /* Clear error status */
-               write32((sata_bar5 + 0x130), 0xFFFFFFFF);
-               write32((sata_bar5 + 0x1b0), 0xFFFFFFFF);
-               write32((sata_bar5 + 0x230), 0xFFFFFFFF);
-               write32((sata_bar5 + 0x2b0), 0xFFFFFFFF);
-               write32((sata_bar5 + 0x330), 0xFFFFFFFF);
-               write32((sata_bar5 + 0x3b0), 0xFFFFFFFF);
+               /* Enable interrupts from the HBA  */
+               byte = read8(sata_bar5 + 0x4);
+               byte |= 1 << 1;
+               write8((sata_bar5 + 0x4), byte);
        }

+       /* Clear error status */
+       write32((sata_bar5 + 0x130), 0xFFFFFFFF);
+       write32((sata_bar5 + 0x1b0), 0xFFFFFFFF);
+       write32((sata_bar5 + 0x230), 0xFFFFFFFF);
+       write32((sata_bar5 + 0x2b0), 0xFFFFFFFF);
+       write32((sata_bar5 + 0x330), 0xFFFFFFFF);
+       write32((sata_bar5 + 0x3b0), 0xFFFFFFFF);
+
        /* Clear SATA status,Firstly we get the AcpiGpe0BlkAddr */
        /* ????? why CIM does not set the AcpiGpe0BlkAddr , but use it??? */
        /* ????? why CIM does not set the AcpiGpe0BlkAddr , but use it??? */
```

Do you know if there is a fix for SeaBIOS or is this a hardware issue?

Thanks,

Paul

[1] http://review.coreboot.org/11998