linux-kernel - Re: [RFC PATCH 0/5] Add smp booting support for Qualcomm ARMv8 SoCs

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Date:	Thu, 16 Apr 2015 16:21:22 +0100
From:	Catalin Marinas <catalin.marinas@....com>
To:	Rob Clark <robdclark@...il.com>
Cc:	Mark Rutland <mark.rutland@....com>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-arm-msm@...r.kernel.org" <linux-arm-msm@...r.kernel.org>,
	Kumar Gala <galak@...eaurora.org>,
	Will Deacon <Will.Deacon@....com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"arm@...nel.org" <arm@...nel.org>,
	"abhimany@...eaurora.org" <abhimany@...eaurora.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [RFC PATCH 0/5] Add smp booting support for Qualcomm ARMv8 SoCs

On Wed, Apr 15, 2015 at 11:01:17AM -0400, Rob Clark wrote:
> On Wed, Apr 15, 2015 at 9:34 AM, Catalin Marinas
> <catalin.marinas@....com> wrote:
> > On Tue, Apr 14, 2015 at 05:48:48PM -0400, Rob Clark wrote:
> >> Just speaking as an outsider to this topic, but seems like most/all
> >> tablets/phones/etc ship with signed firmware.  Which means for most of
> >> the population, upgrading the firmware to a new version which did
> >> support the standard (assuming it existed), isn't really an option on
> >> our devices, any more than fixing buggy acpi tables is on our
> >> laptops..
> >
> > I wouldn't expect most population to build their own kernels on
> > tablets/phones. And even if you could install a custom kernel, mainline
> > rarely runs on such devices because of tons of out of tree patches (just
> > look at the Nexus 9 patches that Kumar pointed at; even ignoring the
> > booting protocol they are extremely far from an upstreamable form).
> 
> my point being, that it happens some times.. for example John Stultz's
> work on nexus7:
> 
> https://plus.google.com/111524780435806926688/posts/DzvpMLmzQiQ
> 
> If this had been a year or two in the future and on some 64b
> snapdragon, and support for devices with non-PSCI fw is rejected, then
> he'd be stuck.
> 
> There are folks who are working to get saner, more-upstream kernels
> working on devices.. and improving kernel infrastructure for
> device-needs (well, in my neck of the woods, there is drm/kms atomic
> and dsi/panel framework stuff.. I'm sure other similar things in other
> kernel domains).  And it seems like that is a good thing to encourage,
> rather than stymie.

I'm not looking to discourage individuals trying to get upstream support
for older boards. Should the need arise, we'll look at options which may
or may not include kernel changes (e.g. wrap the kernel in a shim).

But I'm definitely going to discourage companies like Qualcomm
deliberately ignoring the existing booting protocols while trying to get
their code upstream. This patch series is posted by Qualcomm without
providing any technical reason on why they don't want to/couldn't use
PSCI (well, I guess there is no technical reason but they may not care
much about mainline either).

-- 
Catalin
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