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From: Robert Richter <rric@kernel.org>
To: Jeremy Linton <jeremy.linton@arm.com>
Cc: linux-arm-kernel@lists.infradead.org, lorenzo.pieralisi@arm.com,
	catalin.marinas@arm.com, rjw@rjwysocki.net,
	linux-acpi@vger.kernel.org, sudeep.holla@arm.com,
	will@kernel.org, lenb@kernel.org
Subject: Re: [PATCH v4 2/2] arm64: topology: Use PPTT to determine if PE is a thread
Date: Fri, 2 Aug 2019 15:44:27 +0200	[thread overview]
Message-ID: <20190802134427.dmclik66zcgxapy3@rric.localdomain> (raw)
In-Reply-To: <20190801034634.26913-3-jeremy.linton@arm.com>

On 31.07.19 22:46:34, Jeremy Linton wrote:

> @@ -358,6 +356,10 @@ static int __init parse_acpi_topology(void)
>  		if (topology_id < 0)
>  			return topology_id;
>  
> +		is_threaded = acpi_pptt_cpu_is_thread(cpu);
> +		if (is_threaded < 0)
> +			is_threaded = read_cpuid_mpidr() & MPIDR_MT_BITMASK;
> +

I think the return code handling is error-prone, as in the kernel such
functions are typically used like:

	if (something_is_thread) { ... }

I see this is due to acpi and arch code separation so we cannot simply
move the fallback to pptt code.

So maybe we have a static function cpu_is_thread() in this file that
handles all the logic and directly use check_acpi_cpu_flag() from
there. However, code may change here in case of a rework as I
suggested in patch #1. In both cases the acpi api is more straight
then.

-Robert

>  		if (is_threaded) {
>  			cpu_topology[cpu].thread_id = topology_id;
>  			topology_id = find_acpi_cpu_topology(cpu, 1);

  parent reply	other threads:[~2019-08-02 13:44 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-01  3:46 [PATCH v4 0/2] arm64/PPTT ACPI 6.3 thread flag support Jeremy Linton
2019-08-01  3:46 ` [PATCH v4 1/2] ACPI/PPTT: Add support for ACPI 6.3 thread flag Jeremy Linton
2019-08-01 15:57   ` Sudeep Holla
2019-08-01 16:10     ` Jeremy Linton
2019-08-02 13:05   ` Robert Richter
2019-08-02 15:36     ` Jeremy Linton
2019-08-01  3:46 ` [PATCH v4 2/2] arm64: topology: Use PPTT to determine if PE is a thread Jeremy Linton
2019-08-01 15:58   ` Sudeep Holla
2019-08-02 13:44   ` Robert Richter [this message]
2019-08-02 16:04     ` Jeremy Linton
2019-08-08 20:40 [PATCH v4 0/2] arm64/PPTT ACPI 6.3 thread flag support Jeremy Linton
2019-08-08 20:40 ` [PATCH v4 2/2] arm64: topology: Use PPTT to determine if PE is a thread Jeremy Linton
2019-08-08 22:23   ` Robert Richter

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