Re: [edk2-devel] [PATCH 1/1] EmbeddedPkg/MmcDxe: Added MaxBlock Transfer Limit 65535 in R/W.

[Ard Biesheuvel]

On 4/6/20 4:08 PM, Leif Lindholm wrote:
Hi Gaurav,
Haojian, Tien Hock - can you help review/test this change?

Best Regards,

Leif

On Fri, Apr 03, 2020 at 14:54:07 +0530, Gaurav Jain wrote:
Moved BlockCount calculation below BufferSize Validation checks.
First Ensure Buffersize is Not Zero and multiple of Media BlockSize.
then calculate BlockCount and perform Block checks.

Corrected BlockCount calculation, as BufferSize is multiple of BlockSize,
So adding (BlockSize-1) bytes to BufferSize and
then divide by BlockSize will have no impact on BlockCount.

Reading Large Images from MMC causes errors.
As per SD Host Controller Spec version 4.20,
Restriction of 16-bit Block Count transfer is 65535.
Max block transfer limit in single cmd is 65535 blocks.
Added Max Block check that can be processed is 0xFFFF.
then Update BlockCount on the basis of MaxBlock.

Signed-off-by: Gaurav Jain <gaurav.j...@nxp.com>


Hello Gaurav,

Could you please elaborate on the underlying need for this change? If 
you are considering using this driver for future NXP platforms, I should 
point out that this legacy driver is only kept around for existing 
users, and new users should use the driver stack in MdeModulePkg, which 
is based on the UEFI spec.

--
Ard.



---
  EmbeddedPkg/Universal/MmcDxe/MmcBlockIo.c | 38 ++++++++++++++++++++-----------
  1 file changed, 25 insertions(+), 13 deletions(-)

diff --git a/EmbeddedPkg/Universal/MmcDxe/MmcBlockIo.c 
b/EmbeddedPkg/Universal/MmcDxe/MmcBlockIo.c
index 17c20c0159ba..b508c466d9c5 100644
--- a/EmbeddedPkg/Universal/MmcDxe/MmcBlockIo.c
+++ b/EmbeddedPkg/Universal/MmcDxe/MmcBlockIo.c
@@ -242,6 +242,8 @@ MmcIoBlocks (
    UINTN                   BytesRemainingToBeTransfered;
    UINTN                   BlockCount;
    UINTN                   ConsumeSize;
+  UINT32                  MaxBlock;
+  UINTN                   RemainingBlock;
  
    BlockCount = 1;
    MmcHostInstance = MMC_HOST_INSTANCE_FROM_BLOCK_IO_THIS (This);
@@ -262,19 +264,6 @@ MmcIoBlocks (
      return EFI_NO_MEDIA;
    }
  
-  if (MMC_HOST_HAS_ISMULTIBLOCK(MmcHost) && MmcHost->IsMultiBlock(MmcHost)) {
-    BlockCount = (BufferSize + This->Media->BlockSize - 1) / 
This->Media->BlockSize;
-  }
-
-  // All blocks must be within the device
-  if ((Lba + (BufferSize / This->Media->BlockSize)) > (This->Media->LastBlock 
+ 1)) {
-    return EFI_INVALID_PARAMETER;
-  }
-
-  if ((Transfer == MMC_IOBLOCKS_WRITE) && (This->Media->ReadOnly == TRUE)) {
-    return EFI_WRITE_PROTECTED;
-  }
-
    // Reading 0 Byte is valid
    if (BufferSize == 0) {
      return EFI_SUCCESS;
@@ -285,14 +274,36 @@ MmcIoBlocks (
      return EFI_BAD_BUFFER_SIZE;
    }
  
+  if (MMC_HOST_HAS_ISMULTIBLOCK(MmcHost) && MmcHost->IsMultiBlock(MmcHost)) {
+    BlockCount = BufferSize / This->Media->BlockSize;
+  }
+
+  // All blocks must be within the device
+  if ((Lba + (BufferSize / This->Media->BlockSize)) > (This->Media->LastBlock 
+ 1)) {
+    return EFI_INVALID_PARAMETER;
+  }
+
+  if ((Transfer == MMC_IOBLOCKS_WRITE) && (This->Media->ReadOnly == TRUE)) {
+    return EFI_WRITE_PROTECTED;
+  }
+
    // Check the alignment
    if ((This->Media->IoAlign > 2) && (((UINTN)Buffer & (This->Media->IoAlign - 
1)) != 0)) {
      return EFI_INVALID_PARAMETER;
    }
  
+  // Max block number in single cmd is 65535 blocks.
+  MaxBlock = 0xFFFF;
+  RemainingBlock = BlockCount;
    BytesRemainingToBeTransfered = BufferSize;
    while (BytesRemainingToBeTransfered > 0) {
  
+    if (RemainingBlock <= MaxBlock) {
+      BlockCount = RemainingBlock;
+    } else {
+      BlockCount = MaxBlock;
+    }
+
      // Check if the Card is in Ready status
      CmdArg = MmcHostInstance->CardInfo.RCA << 16;
      Response[0] = 0;
@@ -338,6 +349,7 @@ MmcIoBlocks (
        DEBUG ((EFI_D_ERROR, "%a(): Failed to transfer block and Status:%r\n", 
__func__, Status));
      }
  
+    RemainingBlock -= BlockCount;
      BytesRemainingToBeTransfered -= ConsumeSize;
      if (BytesRemainingToBeTransfered > 0) {
        Lba    += BlockCount;
--
2.7.4



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