Raise Tpl to protect MMC against Timer events

Raise Tpl to protect MMC against Timer events between command and
block IO

An attempt to improve reliability of the MMC card on TC2 when booting
 with the A7 core.

Signed-off-by: Ryan Harkin <ryan.harkin@linaro.org>
Signed-off-by: Steven Kinney <steven.kinney@linaro.org>

1 files changed, 46 insertions, 0 deletions

diff --git a/EmbeddedPkg/Universal/MmcDxe/MmcBlockIo.c b/EmbeddedPkg/Universal/MmcDxe/MmcBlockIo.c
index 81ba7372f..8e13e05c3 100644
--- a/EmbeddedPkg/Universal/MmcDxe/MmcBlockIo.c
+++ b/EmbeddedPkg/Universal/MmcDxe/MmcBlockIo.c
@@ -14,9 +14,50 @@
 

 #include <Library/BaseMemoryLib.h>

 #include <Library/TimerLib.h>

+#include <Library/UefiBootServicesTableLib.h>
 

 #include "Mmc.h"

 

+#define MAX_RETRY_COUNT  1000

+#define CMD_RETRY_COUNT  20

+

+#define TPL_FIRMWARE_INTERRUPTS   ((EFI_TPL)((int) TPL_NOTIFY + 1))
+#define TPL_FOR_MMC_BLOCK_IO      TPL_FIRMWARE_INTERRUPTS
+
+EFI_TPL
+CurrentTpl() {
+  const EFI_TPL Current = gBS->RaiseTPL(TPL_HIGH_LEVEL) ;
+  gBS->RestoreTPL(Current) ;
+  return Current ;
+}
+
+EFI_TPL
+RaiseTplIfLow() {
+  EFI_TPL Current = CurrentTpl() ;
+  /*
+    UEFI Spec states:
+    TPL_CALLBACK Interrupts code executing below TPL_CALLBACK level. Long
+      term operations (such as file system operations and disk I/O) can occur
+      at this level.
+    TPL_NOTIFY Interrupts code executing below TPL_NOTIFY level. Blocking is
+      not allowed at this level. Code executes to completion and returns. If
+      code requires more processing, it needs to signal an event to wait to
+      obtain control again at whatever level it requires. This level is
+      typically used to process low level IO to or from a device.
+    (Firmware Interrupts) This level is internal to the firmware . It is the
+      level at which internal interrupts occur. Code running at this level
+      interrupts code running at the TPL_NOTIFY level (or lower levels). If
+      the interrupt requires extended time to complete, firmware signals
+      another event (or events) to perform the longer term operations so that
+      other interrupts can occur.
+   */
+  if (Current < TPL_FOR_MMC_BLOCK_IO) {
+    Current = gBS->RaiseTPL(TPL_FOR_MMC_BLOCK_IO) ;
+  }
+  return Current ;
+}
+
+
 EFI_STATUS

 MmcNotifyState (

   IN MMC_HOST_INSTANCE *MmcHostInstance,

@@ -405,6 +446,7 @@ MmcIoBlocks (
   EFI_MMC_HOST_PROTOCOL   *MmcHost;

   UINTN                   BytesRemainingToBeTransfered;

   UINTN                   BlockCount;

+  EFI_TPL                 Tpl;
 

   BlockCount = 1;

   MmcHostInstance = MMC_HOST_INSTANCE_FROM_BLOCK_IO_THIS (This);

@@ -484,8 +526,11 @@ MmcIoBlocks (
       // Write a single block

       Cmd = MMC_CMD24;

     }

+    // Raise Tpl to protect against Timer events between command and block IO
+    Tpl = RaiseTplIfLow() ;
     Status = MmcHost->SendCommand (MmcHost, Cmd, CmdArg);

     if (EFI_ERROR (Status)) {

+      gBS->RestoreTPL(Tpl);
       DEBUG ((EFI_D_ERROR, "MmcIoBlocks(MMC_CMD%d): Error %r\n", Cmd, Status));

       return Status;

     }

@@ -493,6 +538,7 @@ MmcIoBlocks (
     if (Transfer == MMC_IOBLOCKS_READ) {

       // Read one block of Data

       Status = MmcHost->ReadBlockData (MmcHost, Lba, This->Media->BlockSize, Buffer);

+      gBS->RestoreTPL(Tpl) ;
       if (EFI_ERROR (Status)) {

         DEBUG ((EFI_D_BLKIO, "MmcIoBlocks(): Error Read Block Data and Status = %r\n", Status));

         MmcStopTransmission (MmcHost);