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MdeModulePkg/.../IdeMode: actualize DRQReady*() comment blocks 

The DRQReady() and DRQReady2() functions only differ in that they poll
different status registers for BSY, ERR, and DRQ: the former looks at the
Status Register (clearing interrupt status), while the latter looks at the
Alternate Status Register (not clearing interrupt status).

They both correctly return a unique status code, EFI_NOT_READY, for the

  BSY==0 && ERR==0 && DRQ==0

case; that is, when the device reports "command complete".

However, the functions' leading comments don't explain this case, so it's
easy to miss in callers. Update the comments.

Cc: Feng Tian <feng.tian@intel.com>
Cc: Star Zeng <star.zeng@intel.com>
Cc: John Snow <jsnow@redhat.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Feng Tian <feng.tian@intel.com>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@19684 6f19259b-4bc3-4df7-8a09-765794883524
This commit is contained in:
Laszlo Ersek 2016-01-19 10:46:34 +00:00 committed by lersek
parent 3b672240e6
commit dfc229f6a6
1 changed files with 25 additions and 6 deletions
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31
MdeModulePkg/Bus/Ata/AtaAtapiPassThru/IdeMode.c
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@ -467,9 +467,18 @@ DRQClear2 (
@param IdeRegisters A pointer to EFI_IDE_REGISTERS data structure.
@param Timeout The time to complete the command, uses 100ns as a unit.
@retval EFI_SUCCESS DRQ bit set within the time out.
@retval EFI_TIMEOUT DRQ bit not set within the time out.
@retval EFI_ABORTED DRQ bit not set caused by the command abort.
@retval EFI_SUCCESS BSY bit cleared and DRQ bit set within the
timeout.
@retval EFI_TIMEOUT BSY bit not cleared within the timeout.
@retval EFI_ABORTED Polling abandoned due to command abort.
@retval EFI_DEVICE_ERROR Polling abandoned due to a non-abort error.
@retval EFI_NOT_READY BSY bit cleared within timeout, and device
reported "command complete" by clearing DRQ
bit.
@note Read Status Register will clear interrupt status.
@ -542,9 +551,19 @@ DRQReady (
@param IdeRegisters A pointer to EFI_IDE_REGISTERS data structure.
@param Timeout The time to complete the command, uses 100ns as a unit.
@retval EFI_SUCCESS DRQ bit set within the time out.
@retval EFI_TIMEOUT DRQ bit not set within the time out.
@retval EFI_ABORTED DRQ bit not set caused by the command abort.
@retval EFI_SUCCESS BSY bit cleared and DRQ bit set within the
timeout.
@retval EFI_TIMEOUT BSY bit not cleared within the timeout.
@retval EFI_ABORTED Polling abandoned due to command abort.
@retval EFI_DEVICE_ERROR Polling abandoned due to a non-abort error.
@retval EFI_NOT_READY BSY bit cleared within timeout, and device
reported "command complete" by clearing DRQ
bit.
@note Read Alternate Status Register will not clear interrupt status.
**/