From: Mac Lin <redacted>

CNS3xxx override the softreset function of ahci_platform ahci_softreset by
cns3xxx_ahci_softreset, which would retry ahci_do_softreset again with pmp=0 if
pmp=15 failed, for the controller has problem receiving D2H Reg FIS of the
different PMP setting of the previous sent H2D Reg FIS.

Following describe the isssue with original ahci_platform driver on
linux-2.6.37-rc3, arm/cns3xxx.

If CONFIG_SATA_PMP is enabled, while not using multiplier and connect the disks
directly to the board, the disk cannot be found due to software reset always
failed.

   ahci ahci.0: forcing PORTS_IMPL to 0x3
   ahci ahci.0: AHCI 0001.0100 32 slots 2 ports 3 Gbps 0x3 impl platform mode
   ahci ahci.0: flags: ncq sntf pm led clo only pmp pio slum part ccc
   scsi0 : ahci_platform
   scsi1 : ahci_platform
   ata1: SATA max UDMA/133 irq_stat 0x00400040, connection status changed irq 65
   ata2: SATA max UDMA/133 mmio [mem 0x83000000-0x83ffffff] port 0x180 irq 65
   ata2: SATA link down (SStatus 0 SControl 300)
   ata1: link is slow to respond, please be patient (ready=0)
   ata1: softreset failed (device not ready)
   ata1: link is slow to respond, please be patient (ready=0)
   ata1: softreset failed (device not ready)
   ata1: link is slow to respond, please be patient (ready=0)
   ata1: softreset failed (device not ready)
   ata1: limiting SATA link speed to 1.5 Gbps
   ata1: SATA link down (SStatus 1 SControl 310)

While using multiplier with CONFIG_SATA_PMP enabled, or using disks directly
without CONFIG_SATA_PMP have no issue. It seems the device is sending D2H Reg
FIS, but controller is not reflecting it on any known means.

Signed-off-by: Mac Lin <redacted>
---
 arch/arm/mach-cns3xxx/devices.c |    2 +-
 drivers/ata/Kconfig             |   11 +++++++++++
 drivers/ata/ahci_platform.c     |   39 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 51 insertions(+), 1 deletions(-)

diff --git a/arch/arm/mach-cns3xxx/devices.c b/arch/arm/mach-cns3xxx/devices.c
index 50b4d31..b496f02 100644
--- a/arch/arm/mach-cns3xxx/devices.c
+++ b/arch/arm/mach-cns3xxx/devices.c

@@ -40,7 +40,7 @@ static struct resource cns3xxx_ahci_resource[] = {

 static u64 cns3xxx_ahci_dmamask = DMA_BIT_MASK(32);

 static struct platform_device cns3xxx_ahci_pdev = {
-       .name           = "ahci",
+       .name           = "ahci-cns3xxx",
       .id             = 0,
       .resource       = cns3xxx_ahci_resource,
       .num_resources  = ARRAY_SIZE(cns3xxx_ahci_resource),

diff --git a/drivers/ata/Kconfig b/drivers/ata/Kconfig
index 36e2319..5d8b1a3 100644
--- a/drivers/ata/Kconfig
+++ b/drivers/ata/Kconfig

@@ -75,6 +75,17 @@ config SATA_AHCI_PLATFORM

         If unsure, say N.

+config SATA_AHCI_CNS3XXX
+       bool "AHCI Support on the Cavium Networks CNS3xxx SOC"
+       depends on ARCH_CNS3XXX
+       depends on SATA_AHCI_PLATFORM
+       help
+         This option enables AHCI platform driver to support CNS3xxx
+         System-on-Chip devices. This is only needed when using CNS3xxx AHCI
+         controller.
+
+         If unsure, say N.
+
 config SATA_FSL
       tristate "Freescale 3.0Gbps SATA support"
       depends on FSL_SOC

diff --git a/drivers/ata/ahci_platform.c b/drivers/ata/ahci_platform.c
index 25d98c8..7d6957f 100644
--- a/drivers/ata/ahci_platform.c
+++ b/drivers/ata/ahci_platform.c

@@ -176,8 +176,47 @@ static int __devexit ahci_remove(struct platform_device *pdev)

       return 0;
 }

+#ifdef CONFIG_SATA_AHCI_CNS3XXX
+/*
+ * TODO: move cns3xxx_ahci_init to here after cns3xxx_pwr*() calls are
+ * thread-safe
+ */
+
+static int cns3xxx_ahci_softreset(struct ata_link *link, unsigned int *class,
+                         unsigned long deadline)
+{
+       int pmp = sata_srst_pmp(link);
+       int ret;
+
+       ret = ahci_do_softreset(link, class, pmp, deadline, ahci_check_ready);
+       if (pmp && ret)
+               return ahci_do_softreset(link, class, 0, deadline,
+                       ahci_check_ready);
+       return ret;
+}
+
+static struct ata_port_operations cns3xxx_ahci_ops = {
+       .inherits               = &ahci_ops,
+       .softreset              = cns3xxx_ahci_softreset,
+};
+
+static const struct ata_port_info cns3xxx_ata_port_info = {
+       .flags          = AHCI_FLAG_COMMON,
+       .pio_mask       = ATA_PIO4,
+       .udma_mask      = ATA_UDMA6,
+       .port_ops       = &cns3xxx_ahci_ops,
+};
+
+struct ahci_platform_data cns3xxx_ahci_platform_data = {
+       .ata_port_info  = &cns3xxx_ata_port_info,
+};
+#endif
+
 static const struct platform_device_id ahci_pltfm_ids[] = {
       { "ahci", },
+#ifdef CONFIG_SATA_AHCI_CNS3XXX
+       { "ahci-cns3xxx", (kernel_ulong_t)&cns3xxx_ahci_platform_data},
+#endif
       { },
 };
 MODULE_DEVICE_TABLE(platform, ahci_pltfm_ids);
--
1.7.3