MdeModulePkg/SerialDxe: Fix return valued in SerialSetAttributes

SerialSetAttributes is meant to match the behavior of the function
EFI_SERIAL_IO_PROTOCOL.SetAttributes() in the UEFI spec (v2.7). This
means the function can only return:
    - EFI_SUCCESS
    - EFI_INVALID_PARAMETER
    - EFI_DEVICE_ERROR

However the function SerialPortSetAttributes may also validly return
EFI_UNSUPPORTED. For instance this is the case of the Xen Console
driver.

EFI_UNSUPPORTED could be also interpreted as "One or more of the attributes
has an unsupported value". So return EFI_INVALID_PARAMETER in that case.

Lastly, to prevent another return slipping in the future, all the errors
but EFI_INVALID_PARAMETER and EFI_UNSUPPORTED will return
EFI_DEVICE_ERROR.

Contributed-under: Tianocore Contribution Agreement 1.1
Signed-off-by: Julien Grall <julien.grall@linaro.org>
Reviewed-by: Star Zeng <star.zeng@intel.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>

1 files changed, 9 insertions, 5 deletions

diff --git a/MdeModulePkg/Universal/SerialDxe/SerialIo.c b/MdeModulePkg/Universal/SerialDxe/SerialIo.c
index 19fc889c25..ee10ec7e05 100644
--- a/MdeModulePkg/Universal/SerialDxe/SerialIo.c
+++ b/MdeModulePkg/Universal/SerialDxe/SerialIo.c
@@ -66,8 +66,9 @@ SerialReset (
                            value of DefaultStopBits will use the device's default number of

                            stop bits.

 

-  @retval EFI_SUCCESS      The device was reset.

-  @retval EFI_DEVICE_ERROR The serial device is not functioning correctly.

+  @retval EFI_SUCCESS           The device was reset.

+  @retval EFI_INVALID_PARAMETER One or more attributes has an unsupported value.

+  @retval EFI_DEVICE_ERROR      The serial device is not functioning correctly.

 

 **/

 EFI_STATUS

@@ -264,8 +265,9 @@ SerialReset (
                            value of DefaultStopBits will use the device's default number of

                            stop bits.

 

-  @retval EFI_SUCCESS      The device was reset.

-  @retval EFI_DEVICE_ERROR The serial device is not functioning correctly.

+  @retval EFI_SUCCESS           The device was reset.

+  @retval EFI_INVALID_PARAMETER One or more attributes has an unsupported value.

+  @retval EFI_DEVICE_ERROR      The serial device is not functioning correctly.

 

 **/

 EFI_STATUS

@@ -323,8 +325,10 @@ SerialSetAttributes (
       DataBits = OriginalDataBits;

       StopBits = OriginalStopBits;

       Status = EFI_SUCCESS;

+    } else if (Status == EFI_INVALID_PARAMETER || Status == EFI_UNSUPPORTED) {

+      return EFI_INVALID_PARAMETER;

     } else {

-      return Status;

+      return EFI_DEVICE_ERROR;

     }

   }