[edk2-devel] [edk2-platforms][Patch 2/3] KabylakeSiliconPkg/BaseSmbusLib: Fix SmBusSendByte value

[Michael D Kinney]

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=3451

Update SmBusSendByte() to write value to Command Register instead of
Host Data registers.

Cc: Chasel Chiu <chasel.chiu at intel.com>
Cc: Nate DeSimone <nathaniel.l.desimone at intel.com>
Signed-off-by: Michael D Kinney <michael.d.kinney at intel.com>
---
 .../Pch/Library/BaseSmbusLib/BaseSmbusLib.c   | 24 +++++++++++++------
 1 file changed, 17 insertions(+), 7 deletions(-)

diff --git a/Silicon/Intel/KabylakeSiliconPkg/Pch/Library/BaseSmbusLib/BaseSmbusLib.c b/Silicon/Intel/KabylakeSiliconPkg/Pch/Library/BaseSmbusLib/BaseSmbusLib.c
index 5d09e18613..68dc698aaf 100644
--- a/Silicon/Intel/KabylakeSiliconPkg/Pch/Library/BaseSmbusLib/BaseSmbusLib.c
+++ b/Silicon/Intel/KabylakeSiliconPkg/Pch/Library/BaseSmbusLib/BaseSmbusLib.c
@@ -201,14 +201,24 @@ InternalSmBusNonBlock (
     HostControl      |= B_PCH_SMBUS_PEC_EN;
   }
   //
-  // Set Host Commond Register.
+  // We do not need Data Register for SendByte Command
   //
-  IoWrite8 (IoPortBaseAddress + R_PCH_SMBUS_HCMD, (UINT8) SMBUS_LIB_COMMAND (SmBusAddress));
-  //
-  // Write value to Host Data 0 and Host Data 1 Registers.
-  //
-  IoWrite8 (IoPortBaseAddress + R_PCH_SMBUS_HD0, (UINT8) Value);
-  IoWrite8 (IoPortBaseAddress + R_PCH_SMBUS_HD1, (UINT8) (Value >> 8));
+  if ((HostControl == V_PCH_SMBUS_SMB_CMD_BYTE) && ((SmBusAddress & BIT0) == B_PCH_SMBUS_WRITE)) {
+    //
+    // Set Host Command Register.
+    //
+    IoWrite8 (IoPortBaseAddress + R_PCH_SMBUS_HCMD, (UINT8)Value);
+  } else {
+    //
+    // Set Host Command Register.
+    //
+    IoWrite8 (IoPortBaseAddress + R_PCH_SMBUS_HCMD, (UINT8) SMBUS_LIB_COMMAND (SmBusAddress));
+    //
+    // Write value to Host Data 0 and Host Data 1 Registers.
+    //
+    IoWrite8 (IoPortBaseAddress + R_PCH_SMBUS_HD0, (UINT8) Value);
+    IoWrite8 (IoPortBaseAddress + R_PCH_SMBUS_HD1, (UINT8) (Value >> 8));
+  }
   //
   // Set Auxiliary Control Regiester.
   //
-- 
2.31.1.windows.1



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