linux-kernel - Re: Fwd: Hid over I2C and ACPI interaction

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Date:	Mon, 09 Jul 2012 11:24:45 +0800
From:	Lan Tianyu <tianyu.lan@...el.com>
To:	Mika Westerberg <mika.westerberg@...ux.intel.com>
CC:	Zhang Rui <rui.zhang@...el.com>, khali@...ux-fr.org,
	ben-linux@...ff.org, w.sang@...gutronix.de, lenb@...nel.org,
	linux-acpi@...r.kernel.org, linux-i2c@...r.kernel.org,
	linux-kernel@...r.kernel.org, jkosina@...e.cz, chatty@...c.fr,
	jj_ding@....com.tw, bhelgaas@...gle.com, abelay@....edu
Subject: Re: Fwd: Hid over I2C and ACPI interaction

On 2012年07月06日 13:52, Mika Westerberg wrote:
> On Thu, Jul 05, 2012 at 03:01:57PM +0800, Zhang Rui wrote:
>> +Note that although these are ACPI devices, we prefer to use PnP drivers
>> for them,
>> +this is because:
>> +1. all the non-ACPI-predefined Devices are exported as PnP devices as
>> well
>> +2. PnP bus is a well designed bus. Probing via PnP layer saves a lot of
>> work
>> +   for the device driver, e.g. getting&  parsing ACPI resources.
>
> (Nice BKM, thanks for sharing)
>
> I have few questions about using PnP drivers instead of pure ACPI drivers.
>
> ACPI 5.0 defined some new resources, for example "Fixed DMA descriptor"
> that has information about the request line + channel for the device to
> use. Hovewer, PnP drivers pass resources as 'struct resource', which
> basically only has start and end - how do you represent all this new stuff
> using 'struct resource'?
>
I think we can add new interface to get acpi specific resources. e.g
struct acpi_resource pnp_get_acpi_resource(...). When the pnp acpi devices
were initialized, put those acpi specific resources into a new resource list
pnpdev->acpi_resources. What pnp_get_acpi_resource does is to get specified
type acpi resources and return. We also need to define some acpi resource types.

ACPI_RESOURCE_DMA
ACPI_RESOURCE_I2C_SERIALBUS
ACPI_RESOURCE_SPI_SERIALBUS
ACPI_RESOURCE_UART_SERIALBUS
ACPI_RESOURCE_COMMON_SERIALBUS
...

How about this? welcome to comments.

> Or should we use acpi_walk_resources() where 'struct resource' is not
> suitable?
>

-- 
Best Regards
Tianyu Lan
linux kernel enabling team
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