linux-kernel - Re: [PATCH v3 2/2] ACPI: AGDI: Add driver for Arm Generic Diagnostic Dump and Reset device

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Date:   Thu, 13 Jan 2022 18:17:13 -0800 (PST)
From:   Ilkka Koskinen <ilkka@...amperecomputing.com>
To:     Lorenzo Pieralisi <lorenzo.pieralisi@....com>
cc:     guohanjun@...wei.com, sudeep.holla@....com, rafael@...nel.org,
        linux@...linux.org.uk, lenb@...nel.org, robert.moore@...el.com,
        linux-acpi@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, patches@...erecomputing.com,
        scott@...amperecomputing.com, darren@...amperecomputing.com,
        james.morse@....com, Ilkka Koskinen <ilkka@...amperecomputing.com>
Subject: Re: [PATCH v3 2/2] ACPI: AGDI: Add driver for Arm Generic Diagnostic
 Dump and Reset device


Hi Lorenzo,

On Wed, 5 Jan 2022, Ilkka Koskinen wrote:
>
> Hi Lorenzo,
>
> On Wed, 5 Jan 2022, Lorenzo Pieralisi wrote:
>> [+James, for SDEI bits]
>> 
>> On Thu, Dec 30, 2021 at 07:37:25PM -0800, Ilkka Koskinen wrote:
>>> ACPI for Arm Components 1.1 Platform Design Document v1.1 [0] specifices
>>> Arm Generic Diagnostic Device Interface (AGDI). It allows an admin to
>>> issue diagnostic dump and reset via an SDEI event or an interrupt.
>>> This patch implements SDEI path.
>>> 
>>> [0] https://developer.arm.com/documentation/den0093/latest/
>>> 
>>> Signed-off-by: Ilkka Koskinen <ilkka@...amperecomputing.com>
>>> ---
>>>  drivers/acpi/arm64/Kconfig  |   8 +++
>>>  drivers/acpi/arm64/Makefile |   1 +
>>>  drivers/acpi/arm64/agdi.c   | 125 ++++++++++++++++++++++++++++++++++++
>>>  3 files changed, 134 insertions(+)
>>>  create mode 100644 drivers/acpi/arm64/agdi.c

<snip>

>>> diff --git a/drivers/acpi/arm64/agdi.c b/drivers/acpi/arm64/agdi.c
>>> new file mode 100644
>>> index 000000000000..6525ccbae5c1
>>> --- /dev/null
>>> +++ b/drivers/acpi/arm64/agdi.c

<snip>

>>>
>>> +static int __init agdi_init(void)
>>> +{
>>> +	int ret;
>>> +	acpi_status status;
>>> +	struct acpi_table_agdi *agdi_table;
>>> +	struct agdi_data pdata;
>>> +	struct platform_device *pdev;
>>> +
>>> +	if (acpi_disabled)
>>> +		return 0;
>> 
>> Why don't we call agdi_init() from acpi_init() as we do for IORT/VIOT ?
>> 
>> I don't think it is necessary to add a device_initcall(), with related
>> ordering dependencies.
>
> That's a good point. I change it.

Actually, I looked at this more carefully. acpi_init() is called in 
subsys_initcall() while sdei_init() is called in subsys_initcall_sync(). 
That is, if I call this function in acpi_init(), SDEI driver won't be 
ready and this driver fails to register the event.

Cheers, Ilkka