efi: rtc-efi: Mark UIE as unsupported

Tools like hwclock attempt to enable the RTC update interrupt (UIE) to
maximize the accuracy of the reported time value. The EFI rtc does not
have interrupt capability so this is a pointless exercise to begin with,
but the generic RTC framework ends up issuing a SetWakeupTime() Runtime
Services call before drawing that conclusion on its own.

Instead, we can mark UIE as unsupported at driver probe time. The net
result is the same, but without the spurious SetWakeupTime() call.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>

diff --git a/drivers/rtc/rtc-efi.c b/drivers/rtc/rtc-efi.c
index 53b589dc34ebe7a7ee6a6466322515b8f62a1f10..d30fb65fbffac7754eb93d585c713b3af9a203e1 100644 (file)
--- a/drivers/rtc/rtc-efi.c
+++ b/drivers/rtc/rtc-efi.c
@@ -218,6 +218,7 @@ static int __init efi_rtc_probe(struct platform_device *dev)
        if (IS_ERR(rtc))
                return PTR_ERR(rtc);
 
+       rtc->uie_unsupported = 1;
        platform_set_drvdata(dev, rtc);
 
        return 0;