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From: John Garry <john.garry@huawei.com>
To: Mika Westerberg <mika.westerberg@linux.intel.com>
Cc: <rjw@rjwysocki.net>, <andriy.shevchenko@linux.intel.com>,
	<linux-acpi@vger.kernel.org>, <lenb@kernel.org>,
	<lorenzo.pieralisi@arm.com>, <linux-kernel@vger.kernel.org>,
	<arnd@arndb.de>, <graeme.gregory@linaro.org>,
	<helgaas@kernel.org>, <linuxarm@huawei.com>,
	<z.liuxinliang@hisilicon.com>
Subject: Re: [RFC PATCH 1/2] ACPI / PNP: Don't add "enumeration_by_parent" devices
Date: Fri, 20 Apr 2018 15:09:30 +0100	[thread overview]
Message-ID: <75eae3ac-228f-d6a4-bb0e-4bd27e35c55d@huawei.com> (raw)
In-Reply-To: <20180420135222.GY2173@lahna.fi.intel.com>

On 20/04/2018 14:52, Mika Westerberg wrote:
> On Fri, Apr 20, 2018 at 02:24:18PM +0100, John Garry wrote:
>> Hi Mika,
>>
>> On 20/04/2018 14:07, Mika Westerberg wrote:
>>> On Fri, Apr 20, 2018 at 06:07:25PM +0800, John Garry wrote:
>>>> +	} else {
>>>> +		device->driver_data = dev;
>>>
>>> I think this deserves a comment explaining why we (ab)use driver_data
>>> like this.
>>
>> Sure, could add. I didn't see any other way for the acpi_device structure to
>> reference the derived PNP device.
>>
>> TBH, This overall approach is not good since we are creating the PNP device
>> in the scan, and then leaving the device in limbo, waiting for the parent to
>> add it, if at all. There's no rule for this.
>>
>> So I'm looking for ideas on how to improve this.
>

Hi Mika,

> One idea is to make pnpacpi_add_device() available outside of PNP and
> call it directly (or some variation) in hisi_lpc.c when it walks over
> its children.
>

I did consider this initially and it seems quite straightforward.

However I think the problem is that we would need to modify the 
acpi_device child resources from FW with kernel-specific resources, 
which does not seem right (I think that is what you meant). As I see, 
this is one reason that we went in the direction of modelling the host 
as an MFD, as we could set the resources of the mfd_cells.

So adding a variant of pnpacpi_add_device() could work, or modifying 
pnpacpi_add_device() to accept a callback to translate the resources. 
But this feature is specific to our very special requirement...

Thanks,
John

> .
>

  reply	other threads:[~2018-04-20 14:09 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-20 10:07 [RFC PATCH 0/2] HISI LPC: Add PNP device support John Garry
2018-04-20 10:07 ` [RFC PATCH 1/2] ACPI / PNP: Don't add "enumeration_by_parent" devices John Garry
2018-04-20 13:07   ` Mika Westerberg
2018-04-20 13:24     ` John Garry
2018-04-20 13:52       ` Mika Westerberg
2018-04-20 14:09         ` John Garry [this message]
2018-04-26 13:49           ` John Garry
2018-04-26 14:08             ` Mika Westerberg
2018-04-26 14:23               ` John Garry
2018-04-26 14:40                 ` Mika Westerberg
2018-04-27  9:17                 ` John Garry
2018-04-30  5:36                   ` Lee Jones
2018-04-30  9:00                     ` John Garry
2018-04-30  9:26                       ` Lee Jones
2018-04-30  9:35                         ` John Garry
2018-04-30 10:46                           ` Lee Jones
2018-04-30 10:57                             ` John Garry
2018-04-20 10:07 ` [RFC PATCH 2/2] HISI LPC: Add PNP device support John Garry
2018-04-20 12:50   ` Andy Shevchenko
2018-04-20 13:09     ` John Garry
2018-04-20 13:28       ` Andy Shevchenko
2018-04-20 13:32         ` John Garry
2018-04-20 13:12   ` Mika Westerberg
2018-04-20 13:36     ` John Garry

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