[cdi-devel] [PATCH v2] ahci: Initialisation/Reset improvements

[Kevin Wolf <kevin@xxxxxxxxxx>]

Surprisingly, real hardware works much better when the disk gets power
and is spun up. Also disable any automatic transition to power
management modes just to be on the safe side.

Before resetting a port, the processing of the command list must be
stopped.

Signed-off-by: Kevin Wolf <kevin@xxxxxxxxxx>
---
v2:
- Removed the long delays that v1 had while trying to wait for a device on an
  empty port

 ahci/ahci.h | 12 +++++++++++-
 ahci/main.c | 52 ++++++++++++++++++++++++++++++++++++++++++++++++----
 2 files changed, 59 insertions(+), 5 deletions(-)

diff --git a/ahci/ahci.h b/ahci/ahci.h
index 24a830b..85d2cd5 100644
--- a/ahci/ahci.h
+++ b/ahci/ahci.h
@@ -94,9 +94,16 @@ enum {
 
 enum {
     PxCMD_ST    = (1 <<  0), /* Start */
+    PxCMD_SUD   = (1 <<  1), /* Spin-Up Device */
+    PxCMD_POD   = (1 <<  2), /* Power On Device */
     PxCMD_FRE   = (1 <<  4), /* FIS Receive Enable */
     PxCMD_FR    = (1 << 14), /* FIS Receive Running */
     PxCMD_CR    = (1 << 15), /* Command List Running */
+    PxCMD_CPS   = (1 << 16), /* Cold Presence State */
+    PxCMD_CPD   = (1 << 20), /* Cold Presence Detection */
+
+    PxCMD_ICC_MASK      = (0xf << 28),
+    PxCMD_ICC_ACTIVE    = (0x1 << 28),
 };
 
 enum {
@@ -114,7 +121,10 @@ enum {
 };
 
 enum {
-    PxSCTL_DET_MASK     = (0xf << 0),
+    PxSCTL_DET_MASK     = (0xf << 0),   /* Device Detection Initialization */
+    PxSCTL_IPM_MASK     = (0xf << 8),   /* Interface Power Management
+                                           Transitions Allowed */
+    PxSCTL_IPM_NONE     = (0x3 << 8),
 };
 
 /* SATA 2.6: "11.3 Software reset protocol" */
diff --git a/ahci/main.c b/ahci/main.c
index 1afc03c..35f5141 100644
--- a/ahci/main.c
+++ b/ahci/main.c
@@ -46,7 +46,7 @@ static int ahci_init_hardware(struct ahci_device* ahci)
 {
     int port;
     bool all_idle;
-    uint32_t cmd, ssts, sig;
+    uint32_t cmd, ssts, sig, sctl;
     int retries;
 
     /* HBA reset (see AHCI 1.3, chapter 10.4.3) */
@@ -89,21 +89,59 @@ static int ahci_init_hardware(struct ahci_device* ahci)
     /* Determine number of command slots */
     ahci->cmd_slots = (reg_inl(ahci, REG_CAP) & CAP_NCS_MASK) >> CAP_NCS_SHIFT;
 
-    /* Allocate Command List and FIS for each port */
+    /* All ports: Power On Device, Spin-Up Device, Link Active */
     for (port = 0; port < MAX_PORTS; port++) {
         if (!(ahci->ports & BIT(port))) {
             continue;
         }
+        cmd = pxreg_inl(ahci, port, REG_PxCMD);
+        cmd &= ~PxCMD_ICC_MASK;
+        cmd |=  PxCMD_POD | PxCMD_SUD | PxCMD_ICC_ACTIVE;
+        pxreg_outl(ahci, port, REG_PxCMD, cmd);
+    }
 
-        /* If there is a device attached, register it */
-        ssts = pxreg_inl(ahci, port, REG_PxSSTS);
+    /* Detect and initialise devices for each port */
+    retries = 10;
+    for (port = 0; port < MAX_PORTS; port++) {
+        if (!(ahci->ports & BIT(port))) {
+            continue;
+        }
+
+        /* If we know there is nothing (Cold Presence Detection supported, but
+         * no device detected), skip the device. */
+        cmd = pxreg_inl(ahci, port, REG_PxCMD);
+        if ((cmd & (PxCMD_CPD | PxCMD_CPS)) == PxCMD_CPD) {
+            continue;
+        }
+
+        /* Check whether there is a device */
+        do {
+            ssts = pxreg_inl(ahci, port, REG_PxSSTS);
+            if ((ssts & PxSSTS_DET_MASK) == PxSSTS_DET_PRESENT) {
+                break;
+            } else if ((ssts & PxSSTS_DET_MASK) == 0 && retries < 10) {
+                /* At least device presence should be detected after 100ms,
+                 * even if Phy communication isn't established yet. */
+                break;
+            } else if (retries) {
+                cdi_sleep_ms(100);
+                retries--;
+            }
+        } while (retries);
 
+        /* If there is a device attached, register it */
         if ((ssts & PxSSTS_DET_MASK) != PxSSTS_DET_PRESENT ||
             (ssts & PxSSTS_IPM_MASK) != PxSSTS_IPM_ACTIVE)
         {
             continue;
         }
 
+        /* Forbid transition to any power mangement states */
+        sctl = pxreg_inl(ahci, port, REG_PxSCTL);
+        sctl &= ~PxSCTL_IPM_MASK;
+        sctl |= PxSCTL_IPM_NONE;
+        pxreg_outl(ahci, port, REG_PxSCTL, sctl);
+
         /* Create a device with the right driver */
         sig = pxreg_inl(ahci, port, REG_PxSIG);
 
@@ -145,6 +183,10 @@ static int ahci_init_hardware(struct ahci_device* ahci)
 void ahci_port_comreset(struct ahci_device* ahci, int port)
 {
     uint32_t sctl = pxreg_inl(ahci, port, REG_PxSCTL);
+    uint32_t cmd = pxreg_inl(ahci, port, REG_PxCMD);
+
+    pxreg_outl(ahci, port, REG_PxCMD, cmd & ~PxCMD_ST);
+    while (pxreg_inl(ahci, port, REG_PxCMD) & PxCMD_CR);
 
     sctl &= ~PxSCTL_DET_MASK;
     sctl |= 0x1;
@@ -154,6 +196,8 @@ void ahci_port_comreset(struct ahci_device* ahci, int port)
 
     sctl &= ~PxSCTL_DET_MASK;
     pxreg_outl(ahci, port, REG_PxSCTL, sctl);
+
+    pxreg_outl(ahci, port, REG_PxCMD, cmd);
 }
 
 static void irq_handler(struct cdi_device* dev)
-- 
2.1.4