MdeModulePkg SataControllerDxe: Calculate ChannelCount based on PI value

[mirror_edk2.git] / MdeModulePkg / Bus / Pci / SataControllerDxe / SataController.c

diff --git a/MdeModulePkg/Bus/Pci/SataControllerDxe/SataController.c b/MdeModulePkg/Bus/Pci/SataControllerDxe/SataController.c
index 7dc40f82e81977224b3da64884c2924766e9180b..d47e918f5757eff15ab5f056f1651635596aede6 100644 (file)
--- a/MdeModulePkg/Bus/Pci/SataControllerDxe/SataController.c
+++ b/MdeModulePkg/Bus/Pci/SataControllerDxe/SataController.c
@@ -366,6 +366,7 @@ SataControllerStart (
   UINT32                            Data32;\r
   UINTN                             TotalCount;\r
   UINT64                            Supports;\r
+  UINT8                             MaxPortNumber;\r
 \r
   DEBUG ((EFI_D_INFO, "SataControllerStart start\n"));\r
 \r
@@ -472,12 +473,31 @@ SataControllerStart (
     Private->DeviceCount          = IDE_MAX_DEVICES;\r
   } else if (IS_PCI_SATADPA (&PciData)) {\r
     //\r
-    // Read Host Capability Register(CAP) to get Number of Ports(NPS) and Supports Port Multiplier(SPM)\r
-    //   NPS is 0's based value indicating the maximum number of ports supported by the HBA silicon.\r
-    //   A maximum of 32 ports can be supported. A value of '0h', indicating one port, is the minimum requirement.\r
+    // Read Ports Implemented(PI) to calculate max port number (0 based).\r
+    //\r
+    Data32 = AhciReadReg (PciIo, R_AHCI_PI);\r
+    DEBUG ((DEBUG_INFO, "Ports Implemented(PI) = 0x%x\n", Data32));\r
+    if (Data32 == 0) {\r
+      Status = EFI_UNSUPPORTED;\r
+      goto Done;\r
+    }\r
+    MaxPortNumber = 31;\r
+    while (MaxPortNumber > 0) {\r
+      if (Data32 & (1 << MaxPortNumber)) {\r
+        break;\r
+      }\r
+      MaxPortNumber--;\r
+    }\r
+    //\r
+    // Make the ChannelCount equal to the max port number (0 based) plus 1.\r
+    //\r
+    Private->IdeInit.ChannelCount = MaxPortNumber + 1;\r
+\r
+    //\r
+    // Read HBA Capabilities(CAP) to get Supports Port Multiplier(SPM).\r
     //\r
     Data32 = AhciReadReg (PciIo, R_AHCI_CAP);\r
-    Private->IdeInit.ChannelCount = (UINT8) ((Data32 & B_AHCI_CAP_NPS) + 1);\r
+    DEBUG ((DEBUG_INFO, "HBA Capabilities(CAP) = 0x%x\n", Data32));\r
     Private->DeviceCount          = AHCI_MAX_DEVICES;\r
     if ((Data32 & B_AHCI_CAP_SPM) == B_AHCI_CAP_SPM) {\r
       Private->DeviceCount = AHCI_MULTI_MAX_DEVICES;\r