Re: [PATCH v2 2/2] RISC-V: defconfig: Enable Goldfish RTC driver

From: Alistair Francis <Alistair.Francis@wdc.com>
To: "paul.walmsley@sifive.com" <paul.walmsley@sifive.com>,
	Anup Patel <Anup.Patel@wdc.com>
Cc: "linux-riscv@lists.infradead.org"
	<linux-riscv@lists.infradead.org>,
	Atish Patra <Atish.Patra@wdc.com>,
	"gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
	"rkir@google.com" <rkir@google.com>,
	"hch@infradead.org" <hch@infradead.org>,
	"aou@eecs.berkeley.edu" <aou@eecs.berkeley.edu>,
	"anup@brainfault.org" <anup@brainfault.org>,
	"palmer@sifive.com" <palmer@sifive.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2 2/2] RISC-V: defconfig: Enable Goldfish RTC driver
Date: Tue, 22 Oct 2019 22:53:05 +0000	[thread overview]
Message-ID: <17db4a6244d09abf867daf2a6c10de6a5cd58c89.camel@wdc.com> (raw)
In-Reply-To: <alpine.DEB.2.21.9999.1910221213490.28831@viisi.sifive.com>

On Tue, 2019-10-22 at 12:23 -0700, Paul Walmsley wrote:
> On Mon, 14 Oct 2019, Anup Patel wrote:
> 
> > > -----Original Message-----
> > > From: Palmer Dabbelt <palmer@sifive.com>
> > > Sent: Saturday, October 12, 2019 11:09 PM
> > > To: Anup Patel <Anup.Patel@wdc.com>
> > > Cc: Paul Walmsley <paul.walmsley@sifive.com>; 
> > > aou@eecs.berkeley.edu;
> > > Greg KH <gregkh@linuxfoundation.org>; rkir@google.com; Atish
> > > Patra
> > > <Atish.Patra@wdc.com>; Alistair Francis <Alistair.Francis@wdc.com
> > > >;
> > > Christoph Hellwig <hch@infradead.org>; anup@brainfault.org;
> > > linux-
> > > riscv@lists.infradead.org; linux-kernel@vger.kernel.org; Anup
> > > Patel
> > > <Anup.Patel@wdc.com>
> > > Subject: Re: [PATCH v2 2/2] RISC-V: defconfig: Enable Goldfish
> > > RTC driver
> > > 
> > > On Tue, 24 Sep 2019 23:38:08 PDT (-0700), Anup Patel wrote:
> > > > We have Goldfish RTC device available on QEMU RISC-V virt
> > > > machine
> > > > hence enable required driver in RV32 and RV64 defconfigs.
> 
> My understanding is that the Goldfish support is still under 
> discussion on the QEMU side and isn't merged yet - is that accurate?
> 
> https://lists.gnu.org/archive/html/qemu-devel/2019-10/msg04904.html
> 
> > > Reviewed-by: Palmer Dabbelt <palmer@sifive.com>
> > > 
> > > IIRC there was supposed to be a follow-up to your QEMU patch set
> > > to rebase
> > > it on top of a refactoring of their RTC code, but I don't see it
> > > in my inbox.  LMK
> > > if I missed it, as QEMU's soft freeze is in a few weeks and I'd
> > > like to make
> > > sure I get everything in.
> > 
> > I was hoping for QEMU RTC refactoring to be merged soon but it has
> > not
> > happened so far. I will wait couple of more days then send v3 of
> > QEMU
> > patches.
> 
> The patch looks fine to me, but let's wait until the underlying
> support 
> actually appears on the QEMU "hardware".  Could you resend once
> that's 
> happened?

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.

Alistair

> 
> thanks,
> 
> - Paul