Ryan Harkin a4626006bb EmbeddedPkg/Lan9118Dxe: use MemoryFence
When reviewing my LAN9118 driver PCD patch [1], Ard Biesheuvel noted
that most calls to gBS->Stall() in this driver seem to be used to
prevent timing issues between the device updating data and the host
reading the values.  And that replacing most of these calls with a
MemoryFence() would be more robust.

The only exceptions are the stalls that are enclosed inside retry loops:

 - in the AutoNegotiate() function.
   This stall is waiting for the link to negotiate, which may require
   stalling until it is ready.

 - in the Lan9118Initialize() function.
   These two stalls are waiting for devices and time out after a number
   of retries.

 - in the SoftReset() function.
   This stall is inside a loop where the comment states:
   "If time taken exceeds 100us, then there was an error condition"

In these instances, I kept the stall, but also added a MemoryFence().

[1] http://article.gmane.org/gmane.comp.bios.edk2.devel/7389

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ryan Harkin <ryan.harkin@linaro.org>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
2016-02-10 17:56:39 +01:00
2016-02-03 18:42:21 +00:00
2014-10-14 16:08:15 +00:00
2014-10-14 16:08:15 +00:00
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Acidanthera UEFI Development Kit based on EDK II edk2-stable202405
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