Re: [PATCH v3 6/7] ACPI: enable ACPI_DBG2_TABLE on ARM64

From: Aleksey Makarov <amakarov.linux@gmail.com>
To: Peter Hurley <peter@hurleysoftware.com>,
	Aleksey Makarov <aleksey.makarov@linaro.org>,
	linux-acpi@vger.kernel.org
Cc: Matthias Brugger <mbrugger@suse.com>,
	Russell King <linux@arm.linux.org.uk>,
	Graeme Gregory <graeme.gregory@linaro.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	"Rafael J . Wysocki" <rjw@rjwysocki.net>,
	linux-kernel@vger.kernel.org,
	Leif Lindholm <leif.lindholm@linaro.org>,
	Christopher Covington <cov@codeaurora.org>,
	linux-serial@vger.kernel.org,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will.deacon@arm.com>, Al Stone <ahs3@redhat.com>,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v3 6/7] ACPI: enable ACPI_DBG2_TABLE on ARM64
Date: Thu, 3 Mar 2016 14:41:17 +0300	[thread overview]
Message-ID: <56D822DD.2030400@gmail.com> (raw)
In-Reply-To: <56D5D08E.3030902@hurleysoftware.com>

On 03/01/2016 08:25 PM, Peter Hurley wrote:
> On 03/01/2016 09:02 AM, Aleksey Makarov wrote:
>>
>>
>> On 03/01/2016 05:52 PM, Peter Hurley wrote:
>>> On 02/29/2016 04:42 AM, Aleksey Makarov wrote:
>>>> SBBR mentions DBG2 as a mandatory ACPI table.
>>>> So enable it for ARM64
>>>
>>> Why does this have to be opted-in per-arch?
>>
>> DBG2 can specify earlycons.  They should start as soon as possible.
>> On ARM64 it is just after boot tables become available (in arch_init()).
>> So it has to be per-arch unless we decide not to start earlycons on 
>> DBG2 ports.
> 
> OF does all that already but the earlycon opt-in is not per-arch.

In the last next-XXXX kernel support for OF earlycon depends on
CONFIG_OF_EARLY_FLATTREE which *is* per-arch.

Probably we need the same kind of configuration option here,
something like CONFIG_ACPI_BOOT_TABLES instead of ACPI_DBG2_TABLE.

>>>> Signed-off-by: Aleksey Makarov <aleksey.makarov@linaro.org>
>>>> ---
>>>>  arch/arm64/Kconfig       | 1 +
>>>>  arch/arm64/kernel/acpi.c | 2 ++
>>>>  2 files changed, 3 insertions(+)
>>>>
>>>> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
>>>> index 9dc5209..0b614d4 100644
>>>> --- a/arch/arm64/Kconfig
>>>> +++ b/arch/arm64/Kconfig
>>>> @@ -3,6 +3,7 @@ config ARM64
>>>>  	select ACPI_CCA_REQUIRED if ACPI
>>>>  	select ACPI_GENERIC_GSI if ACPI
>>>>  	select ACPI_REDUCED_HARDWARE_ONLY if ACPI
>>>> +	select ACPI_DBG2_TABLE if ACPI
>>>>  	select ARCH_HAS_DEVMEM_IS_ALLOWED
>>>>  	select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE
>>>>  	select ARCH_HAS_ELF_RANDOMIZE
>>>> diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c
>>>> index d1ce8e2..3370046 100644
>>>> --- a/arch/arm64/kernel/acpi.c
>>>> +++ b/arch/arm64/kernel/acpi.c
>>>> @@ -208,6 +208,8 @@ void __init acpi_boot_table_init(void)
>>>>  		pr_err("Failed to init ACPI tables\n");
>>>>  		if (!param_acpi_force)
>>>>  			disable_acpi();
>>>> +	} else {
>>>> +		acpi_probe_device_table(dbg2);
>>>>  	}
>>>>  }
>>>>  
>>>>
>>>
> 
> 
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