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[209.132.180.67]) by mx.google.com with ESMTP id qn24si12263756ejb.200.2019.10.22.21.08.12; Tue, 22 Oct 2019 21:08:36 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=pass header.i=@brainfault-org.20150623.gappssmtp.com header.s=20150623 header.b="yLN/ddNF"; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732668AbfJWDYg (ORCPT + 99 others); Tue, 22 Oct 2019 23:24:36 -0400 Received: from mail-wm1-f65.google.com ([209.85.128.65]:50702 "EHLO mail-wm1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731772AbfJWDYf (ORCPT ); Tue, 22 Oct 2019 23:24:35 -0400 Received: by mail-wm1-f65.google.com with SMTP id q13so9405437wmj.0 for ; Tue, 22 Oct 2019 20:24:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=brainfault-org.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=PoiwGNtU0nAEwpqhaQ40WOeNzy+Ug1D1A+7yaqwVZpE=; b=yLN/ddNFMfFhvPjBZjTwKqoSwWn/DGdu7QUqpRbP8p9LI1mFK7KIlnrmHTLH01uos+ X0D82O2AYz2IOS9/+jyeTWKP9FcdB/e3uP6Z42DJbWTV6MQr7OkuzYq3kjk1RuEoOSOC eNv3Qo7LIIG+xOTLtiUJ+6EnRnxxTFzlGvAGBHGPUMmYKgEhFhfnbJFhQI1rQPdG1OiE d96LttnBqOssIU7NYDQc5/uF1ZD1QnrxEj/9dMaee9uPD4JB1Vjxwda0O5TfOCTW1vBp YBogOBQGt8j3ddQYskXwVEGM3mtoVnSL2pbeaIDRQvrjheAM3nxeNfolhNL/blZzk/9l TX+Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=PoiwGNtU0nAEwpqhaQ40WOeNzy+Ug1D1A+7yaqwVZpE=; b=BcXE0W73TpoM4OcN+LnNmPyKLRo22ZZDfFfaTFJKCatwYYQqciZmHbsyEqJt1GjFRS V5Re3g7X8DcBjoZOZjveTmIeCaiEQDJ4kSWE+SNShO+nnNUuneWsmfgUnjpE+dTdQh+c 1tiohX4B08cZ8y78r0x8/+Iri9DdQ7B5vWz1x+eLZT9K3dANZKayUbJc/u7LEzErgNEc o34/IgA6v7P7q1qPJpf/H5ZjViKAw8Mm6OyNxI7PoaXGDczrJoWzLC/00DgohyvkX6Yq VsZBpehp97vlAhnLeOHg/VuGI5Ec4kGJOM3IgDNC0Xf8HKsmxjkqEZ7J7GUnn6bBgily B0iA== X-Gm-Message-State: APjAAAUTP7qTx6aet/7iP2FSR/gu5TotvnzK60TT4zMmLuL7q+4vsaqM y2TSie8cJhr0C4hbX4du2dS9FCpV2X5BSxKEGoLsuA== X-Received: by 2002:a1c:9695:: with SMTP id y143mr5676311wmd.103.1571801071659; Tue, 22 Oct 2019 20:24:31 -0700 (PDT) MIME-Version: 1.0 References: <20190925063706.56175-3-anup.patel@wdc.com> <17db4a6244d09abf867daf2a6c10de6a5cd58c89.camel@wdc.com> In-Reply-To: From: Anup Patel Date: Wed, 23 Oct 2019 08:54:19 +0530 Message-ID: Subject: Re: [PATCH v2 2/2] RISC-V: defconfig: Enable Goldfish RTC driver To: Paul Walmsley Cc: Alistair Francis , Anup Patel , "linux-riscv@lists.infradead.org" , Atish Patra , "gregkh@linuxfoundation.org" , "rkir@google.com" , "hch@infradead.org" , "aou@eecs.berkeley.edu" , "palmer@sifive.com" , "linux-kernel@vger.kernel.org" Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Oct 23, 2019 at 6:37 AM Paul Walmsley wrote: > > On Tue, 22 Oct 2019, Alistair Francis wrote: > > > I think it makese sense for this to go into Linux first. > > > > The QEMU patches are going to be accepted, just some nit picking to do > > first :) > > > > After that we have to wait for a PR and then a QEMU release until most > > people will see the change in QEMU. In that time Linux 5.4 will be > > released, if this can make it into 5.4 then everyone using 5.4 will get > > the new RTC as soon as they upgrade QEMU (QEMU provides the device > > tree). If this has to wait until QEMU has support then it won't be > > supported for users until even later. > > > > Users are generally slow to update kernels (buildroot is still using > > 5.1 by default for example) so the sooner changes like this go in the > > better. > > The defconfigs are really just for kernel developers. We expect users to > define their own Kconfigs for their own needs. > > If using the Goldfish code really is what we all want to do (see below), > then the kernel patch that should go in right away -- which also has no > dependence on what QEMU does -- would be the first patch of this series: > > https://lore.kernel.org/linux-riscv/20190925063706.56175-2-anup.patel@wdc.com/ > > And that should go in via whoever is maintaining the Goldfish driver, not > the RISC-V tree. (It looks like drivers/platform/goldfish is completely > unmaintained - a red flag! - so probably someone needs to persuade Greg or > Andrew to take it.) GregKH has already queued this for Linux-5.5 and you can see this commit present in linux-next tree: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/log/drivers/platform/goldfish?h=next-20191022 > > Incidentally, just looking at drivers/platform/goldfish, that driver seems > to be some sort of Google-specific RPC driver. Are you all really sure Nopes, it's not RPC driver. In fact, all Goldfish virtual platform devices are MMIO devices. > you want to enable that just for an RTC? Seems like overkill - there are > much simpler RTCs out there. No, it's not overkill. All Goldfish virtual platform devices are quite simple MMIO devices having bare minimum registers required for device functioning. The problem is VirtIO spec does not define any RTC device so instead of inventing our own virtual RTC device we re-use RTC device defined in Goldfish virtual platform for QEMU virt machine. This way we can re-use the Linux Goldfish RTC driver. BTW, I will send-out QEMU Goldfish RTC patches today or tomorrow addressing nit comments from Alistair. Regards, Anup