From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 305883033EB for ; Fri, 28 Aug 2026 07:27:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787902031; cv=none; b=fi4WSe9KnW4sX3bYocbSFgHpIXzKCONqmQZ7DvHOG8iuM6e6AnBA9XVStEBM7fA1x34K1dMWxn/hRuvhHw7mPJQaodjakDmk12+DGO57oXyBnTd0mTBB78jnm0YbIlJz2xjszrh6QQDs9F4PR2Cw1RUGvdDNUmzLbPTi4U9xNSI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787902031; c=relaxed/simple; bh=YOaIooRmfC3FPrSaNswv8niRo3TmeCLk0mVieo8uMrg=; h=MIME-Version:Date:From:To:Cc:Message-Id:In-Reply-To:References: Subject:Content-Type; b=WtuzLu0Jlfx3qauLeC7IMxAu/3rIZy6PbAf1iT+//BBqf2Hrw20T7peowv3Sty8zlA9sqJpzi/K28zfwBgmCUIAgGvT5y54ucKj9S5VyRXyJuRVN7dp9QPBgaHVnuFMD1Vis68501FbSxYlzZrGbcEdAVtskeDt4oERNfqbvDwQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=EBGRt2a4; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="EBGRt2a4" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 76F021F000E9; Fri, 28 Aug 2026 07:27:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1787902029; bh=k2vBzac2CbGqM8xG3fuwgDkMdJk6+vPRFv4ESM0iG2E=; h=Date:From:To:Cc:In-Reply-To:References:Subject; b=EBGRt2a4v1xa51snOqUK2SF6ho/Q8X6bJyegq8JDCIVy12op5oMFnj2HQ1SEvVl0N awlyGqKsR68ZoPbxugbXXBCQL+gaEoXq0yN+oZHB96pVANJy1r1SZ9ssfOY35/eHVH JJLiQES8dXMqCvHA/eZetxa0va1jI4HqTk1YugblFsAPO4axQpRO/JZTrcNsqbqZzH NTaK9EaXn6mbqt3j8uLFSTfk2DtDAO+LCbdqXYRfCDhh2vVX7NLTHWcr+L7tzyX1g4 77ZDBjaCNFeKFfVNmd74eVNCn4Di5CPN3+zgA7XRZ5hjnEf/F9X+LQiCYpvn+aOZbY MypdbU4o1Wcew== Received: from ams-compute-02.internal (ams-compute-02.internal [10.64.2.62]) by mailfauth.ams.internal (Postfix) with ESMTP id D230C1980064; Fri, 28 Aug 2026 03:27:07 -0400 (EDT) Received: from ams-imap-11 ([10.64.2.31]) by ams-compute-02.internal (MEProxy); Fri, 28 Aug 2026 03:27:07 -0400 X-ME-Sender: X-ME-Proxy-Cause: dmFkZTGKC7MJVsVhwe7apdyGUvleWgqZguDJI/SNNS1FzJ8hsWOiVRzxWnmF1rq8Soikfy 7XeSva86wvoFj9ysLgkIXIHOStH/wOg2Qtg6/mFUw+KMM0kXNfbmQd69Hg54MJpR6RDrNM vevQjW+cPRY83Rgxqpf9OXBIqmVIz9jO8n1uR0PbB3o3NT4kdH7SRMIOcbVlVAPKpetbTb 1pDIlJU+36zzvnRN83CTlYVuENfUI9AumZk5Q9NTZQmngHrB8hzBaYIshl3qtl660SqHsc Q688sfFJAx4XoQq1ej0WiN9ft6VgIgTq4pohWiJ54KHagKZE/dHFvzRtZUeOg0uX35lmoV /09Tzt/Eof5BGhbi+ri6wdOx26pZutZrjBwFIfwK+v3+FzVcjgLwQB4lWRMujVjmDa8Xhx mtE87RcmGaOsNdd3n0gZi7+mKPk5zrbMEbSvFMqWLp6H7QkKI09EK7bWWfL6qwvAWWOkCe EXx2u3cWnckVPjYU61rfm10XSFIAun7OFox3eeSiib9fmJIszqznWyNus+9v/B96Uu9scZ zdtwOX0GIBBGObYfvjqHbi48YWYPebOofCETaw1dQa1KwS/+6BJdhgjnU8O8VFU99MrzdB +5jErgjGqngQwyJOzIHrg14MHt9n0mWY5bYNkDYeLHGxxls6wK15SnGBD4LA X-ME-Proxy: Feedback-ID: ice86485a:Fastmail Received: by mailuser.ams.internal (Postfix, from userid 501) id A8123F8007B; Fri, 28 Aug 2026 03:27:05 -0400 (EDT) X-Mailer: MessagingEngine.com Webmail Interface Precedence: bulk X-Mailing-List: linux-rtc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Date: Fri, 28 Aug 2026 09:26:42 +0200 From: "Ard Biesheuvel" To: "Johnny.Fan" , "Alexandre Belloni" , linux-rtc@vger.kernel.org Cc: "Feng Tang" , linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org, cix-kernel-upstream@cixtech.com, bob.zhang@cixtech.com, jie.fu@cixtech.com Message-Id: <549999fa-4b1a-4f53-872a-9036a377f8cf@app.fastmail.com> In-Reply-To: <20260828031519.2749354-1-johnny.fan@cixtech.com> References: <20260828031519.2749354-1-johnny.fan@cixtech.com> Subject: Re: [PATCH] rtc: efi: restore alarm support with runtime capability probe Content-Type: text/plain Content-Transfer-Encoding: 7bit Hello Johnny, On Fri, 28 Aug 2026, at 05:15, Johnny.Fan wrote: > From: "Johnny.Fan" > > Restore the EFI RTC alarm functionality (read_alarm/set_alarm and > procfs output) that was removed by commit 18a3510bc87d ("rtc: efi: > Remove wakeup functionality"). > > The removal was motivated by the observation that many EFI platforms > lack RTC wakeup support while also omitting the RT_PROP table, causing > the wakeup capability to be incorrectly advertised. While that is > true, removing the feature entirely also breaks platforms where the > wakeup runtime service actually works. > > On CIX SoCs with an I2C-connected RTC, the firmware owns the RTC and > exposes it via EFI runtime services. Using the native I2C RTC driver > under Linux breaks Windows, which relies on EFI runtime services to > access the RTC. rtc-efi is therefore the only viable option for > shared RTC access across operating systems, and it needs working > alarm/wakeup support. > Why does it need working alarm/wakeup support? I'm not saying we shouldn't bring it back, but this deserves a bit of motivation, no?