[PATCHv2 3/3] MdeModulePkg/SdMmcPciHcDxe: Fix SdMmcMmcLegacy bus timing handling

["Albecki, Mateusz" <mateusz.albecki@intel.com>]

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=2218

There is a bug in current driver code that makes
it impossible for it to work with devices that
only work in legacy speed mode since the function
EmmcSwitchToHighSpeed will return with EFI_INVALID_ARGUMENT
for such bus mode. Since the logic in that function will
work well for SdMmcMmcLegacy this patch just allows
to call this function with SdMmcMmcLegacy bus mode.

Signed-off-by: Mateusz Albecki <mateusz.albecki@intel.com>
Cc: Hao A Wu <hao.a.wu@intel.com>
Cc: Marcin Wojtas <mw@semihalf.com>
---
 MdeModulePkg/Bus/Pci/SdMmcPciHcDxe/EmmcDevice.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/MdeModulePkg/Bus/Pci/SdMmcPciHcDxe/EmmcDevice.c b/MdeModulePkg/Bus/Pci/SdMmcPciHcDxe/EmmcDevice.c
index 3598a8538a..082904ccc5 100644
--- a/MdeModulePkg/Bus/Pci/SdMmcPciHcDxe/EmmcDevice.c
+++ b/MdeModulePkg/Bus/Pci/SdMmcPciHcDxe/EmmcDevice.c
@@ -794,7 +794,7 @@ EmmcSwitchToHighSpeed (
   EFI_STATUS  Status;
   BOOLEAN     IsDdr;
 
-  if ((BusMode->BusTiming != SdMmcMmcHsSdr && BusMode->BusTiming != SdMmcMmcHsDdr) ||
+  if ((BusMode->BusTiming != SdMmcMmcHsSdr && BusMode->BusTiming != SdMmcMmcHsDdr && BusMode->BusTiming != SdMmcMmcLegacy) ||
       BusMode->ClockFreq > 52) {
     return EFI_INVALID_PARAMETER;
   }
@@ -1244,6 +1244,12 @@ EmmcSetBusMode (
   } else if (BusMode.BusTiming == SdMmcMmcHs200) {
     Status = EmmcSwitchToHS200 (PciIo, PassThru, Slot, Rca, &BusMode);
   } else {
+    //
+    // Note that EmmcSwitchToHighSpeed is also called for SdMmcMmcLegacy
+    // bus timing. This is because even though we might not want to
+    // change the timing itself we still want to allow customization of
+    // bus parameters such as clock frequency and bus width.
+    //
     Status = EmmcSwitchToHighSpeed (PciIo, PassThru, Slot, Rca, &BusMode);
   }
 
-- 
2.14.1.windows.1

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