linux-kernel - Re: [PATCH V7 5/7] ACPI: Delay the enumeration on the devices whose dependency has not met

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Date:   Thu, 16 Mar 2017 10:21:58 +0800
From:   "zhichang.yuan" <yuanzhichang@...ilicon.com>
To:     "Rafael J. Wysocki" <rjw@...ysocki.net>
CC:     <catalin.marinas@....com>, <will.deacon@....com>,
        <robh+dt@...nel.org>, <frowand.list@...il.com>,
        <bhelgaas@...gle.com>, <rafael@...nel.org>, <mark.rutland@....com>,
        <arnd@...db.de>, <linux-arm-kernel@...ts.infradead.org>,
        <linux-acpi@...r.kernel.org>, <lorenzo.pieralisi@....com>,
        <benh@...nel.crashing.org>, <linux-kernel@...r.kernel.org>,
        <linuxarm@...wei.com>, <devicetree@...r.kernel.org>,
        <linux-pci@...r.kernel.org>, <linux-serial@...r.kernel.org>,
        <minyard@....org>, <liviu.dudau@....com>, <zourongrong@...il.com>,
        <john.garry@...wei.com>, <gabriele.paoloni@...wei.com>,
        <zhichang.yuan02@...il.com>, <kantyzc@....com>,
        <xuwei5@...ilicon.com>
Subject: Re: [PATCH V7 5/7] ACPI: Delay the enumeration on the devices whose
 dependency has not met

Hi, Rafael,

Thanks for your review!

On 2017/3/14 5:24, Rafael J. Wysocki wrote:
> On Monday, March 13, 2017 10:42:41 AM zhichang.yuan wrote:
>> In commit 40e7fcb1929(ACPI: Add _DEP support to fix battery issue on Asus
>> T100TA), the '_DEP' was supported to solve the dependency of Asus battery. But
>> this patch is specific to Asus battery device.
>> In the real world, there are other devices which need the dependency to play the
>> role on the enumeration order. For example, all the Hip06 LPC
>> periperals(IPMI-BT, uart, etc) must be scanned after the LPC host driver
>> finished the probing. So, it makes sense to add a checking whether the ACPI
>> device meet all the dependencies during its enumeration slot, if not, the
>> enumeration will be delayed till all dependency master finish their work.
>>
>> This patch adds the dependency checking in ACPI enumeration, also the
>> corresponding handling to retrigger the Hip06 LPC peripherals' scanning.
> 
> AFAICS, _DEP is generally abused in the wild and cannot be made generic.  Sorry.
> 

>From the ACPI specification, _DEP is for operation region accesses.
You are right...

How about we add a ACPI handler for our LPC bus?? Just like amba.
In this way, we also can solve the issue about LPC enumeration order.

Thanks,
Zhichang


> Thanks,
> Rafael
> 
> 
> .
>