From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751547AbcFEJf5 (ORCPT ); Sun, 5 Jun 2016 05:35:57 -0400 Received: from mx2.suse.de ([195.135.220.15]:52266 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750826AbcFEJf4 (ORCPT ); Sun, 5 Jun 2016 05:35:56 -0400 From: Alexander Graf To: rtc-linux@googlegroups.com Cc: leif.lindholm@linaro.org, linux-kernel@vger.kernel.org, Alexandre Belloni , Alessandro Zummo , Ard Biesheuvel Subject: [PATCH] rtc: efi: Fail probing if RTC reads don't work Date: Sun, 5 Jun 2016 11:35:56 +0200 Message-Id: <1465119356-129799-1-git-send-email-agraf@suse.de> X-Mailer: git-send-email 1.8.5.6 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org While the EFI spec mandates an RTC, not every implementation actually adheres to that rule (or can adhere to it - some systems just don't have an RTC). For those, we really don't want to probe the EFI RTC driver at all, because if we do we'd get a non-functional driver that does nothing useful but only spills our kernel log with warnings. Signed-off-by: Alexander Graf --- drivers/rtc/rtc-efi.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/rtc/rtc-efi.c b/drivers/rtc/rtc-efi.c index 96d3860..0130afd 100644 --- a/drivers/rtc/rtc-efi.c +++ b/drivers/rtc/rtc-efi.c @@ -259,6 +259,12 @@ static const struct rtc_class_ops efi_rtc_ops = { static int __init efi_rtc_probe(struct platform_device *dev) { struct rtc_device *rtc; + efi_time_t eft; + efi_time_cap_t cap; + + /* First check if the RTC is usable */ + if (efi.get_time(&eft, &cap) != EFI_SUCCESS) + return -ENODEV; rtc = devm_rtc_device_register(&dev->dev, "rtc-efi", &efi_rtc_ops, THIS_MODULE); -- 1.8.5.6