linux-kernel - Re: [PATCH v2 1/3] ARM: tegra: basic support for Trusted Foundations

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Message-ID: <CAAVeFuLc57pV=To5yaE5x9mrVy1yknH2e90QockCiNbEXRm0WQ@mail.gmail.com>
Date:	Fri, 14 Jun 2013 17:27:09 +0900
From:	Alexandre Courbot <gnurou@...il.com>
To:	Stephen Warren <swarren@...dotorg.org>
Cc:	Alexandre Courbot <acourbot@...dia.com>,
	Joseph Lo <josephl@...dia.com>,
	Karan Jhavar <kjhavar@...dia.com>,
	Varun Wadekar <vwadekar@...dia.com>,
	Chris Johnson <CJohnson@...dia.com>,
	Matthew Longnecker <MLongnecker@...dia.com>,
	Russell King - ARM Linux <linux@....linux.org.uk>,
	Tomasz Figa <tomasz.figa@...il.com>,
	Dave Martin <Dave.Martin@....com>,
	Jassi Brar <jassisinghbrar@...il.com>,
	"devicetree-discuss@...ts.ozlabs.org" 
	<devicetree-discuss@...ts.ozlabs.org>,
	"linux-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v2 1/3] ARM: tegra: basic support for Trusted Foundations

On Fri, Jun 14, 2013 at 4:19 AM, Stephen Warren <swarren@...dotorg.org> wrote:
> On 06/13/2013 03:12 AM, Alexandre Courbot wrote:
>> Add basic support for booting secondary processors on Tegra devices
>> using the Trusted Foundations secure monitor.
>>
>> Signed-off-by: Alexandre Courbot <acourbot@...dia.com>
>> ---
>>  Documentation/devicetree/bindings/arm/tegra.txt    | 11 +++++
>>  .../devicetree/bindings/vendor-prefixes.txt        |  1 +
>>  arch/arm/configs/tegra_defconfig                   |  1 +
>
> The defconfig change should be a separate patch, so that I can squash it
> into any other defconfig updates separately from all the code changes.

Ok, moved that part into its own patch.

>> diff --git a/arch/arm/mach-tegra/firmware.c b/arch/arm/mach-tegra/firmware.c
>
>> +void __init tegra_init_firmware(void)
>> +{
>> +     struct device_node *node;
>> +
>> +     if (!of_have_populated_dt())
>> +             return;
>> +
>> +     node = of_find_compatible_node(NULL, NULL, "tl,trusted-foundations");
>> +     if (node && !IS_ENABLED(CONFIG_TEGRA_TRUSTED_FOUNDATIONS))
>> +             pr_warn("Trusted Foundations detected but support missing!\n");
>> +#if IS_ENABLED(CONFIG_TEGRA_TRUSTED_FOUNDATIONS)
>> +     else if (node)
>> +             register_firmware_ops(&tegra_trusted_foundations_ops);
>> +#endif
>> +}
>
> Is it worth continuing on in the node && !IS_ENABLED case here? After
> all, we can be pretty certain that the write to the CPU reset vector is
> immediately going to trap...

That's what was happening until 3.9, but from 3.10 on the trap is
apparently handled and the boot completes (although with only one
processor).

> I suppose that perhaps without SMP, cpuidle, suspend, ... we could keep
> running, but that seems a little niche.

If we can keep running, even in degraded mode, I see no reason to
panic. The problem is well reported in the kernel log, and having a
running system might be helpful to analyze the issue.

Thanks,
Alex.
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