Re: [PATCH] acerhdf: Limit modalias matching to supported boards

[Peter Feuerer <peter@piie.net>]

Bjorn Helgaas writes:

> On Monday 05 October 2009 09:56:51 am Stefan Bader wrote:
>> Bjorn Helgaas wrote:
>> > On Monday 05 October 2009 06:05:54 am Stefan Bader wrote:
>> >>>>>> <stefan.bader@canonical.com> wrote:
>> >>>>>>>>> I search my acerhdf-inbox for the people who sent me the BIOS 
>> >>>>>>>>> versions,
>> >>>>>>>> maybe they still have the netbook and can me send the modalias 
>> >>>>>>>> content. I'll

...

>> > 
>> > This smells like a maintenance problem.  The driver only works on the
>> > specific machines and BIOS versions compiled into it.  That means you
>> > have to update the driver every time a new machine comes out.  A major
>> > goal of ACPI is to avoid stuff like that.
>> > 
>> > Are you sure there's no way to make this driver work in a generic way,
>> > e.g., by claiming an ACPI device?
>> 
>> The driver is currently only targeted at a small set of netbooks and even there 
>> some registers have changed between sub models or bios versions.
>> The functions are implemented by poking and reading bits from the EC. No acpi 
>> interface to which one relate as far as I know. Maybe wmi, but from the 
>> experiences with acer-wmi, I doubt anything works. At least acer-wmi now 
>> explicitly blacklist these models for uselessness.
>> So the driver performs very strict bios version checks and every unknown 
>> version get a big warning printed. Which you do not want to be issued on every 
>> hardware of one of these vendors. Which happens with the driver as it is now.
> 
> I understand the motivation for the current patch, and I'm not asking
> about it in particular.  My concern is about the underlying structure
> of the driver.
> 
> I'm just asking why we would want a driver that requires an update
> for every new machine.  That sort of ongoing maintenance is a good
> sign that we're doing something wrong.

Hi Bjorn,

as Stefan already mentioned, is the driver only targeting a very small set 
of (very popular) netbooks. The vendor supposed to control the fan only by 
BIOS. I think it is not ment to be controlled by the OS at all, as there is 
no official Windows support neither.
The successor series of the supported netbooks even don't have the 
register in EC anymore. So I think there won't be much changes caused by new 
devices in the future anymore. Besides that, I don't think there's a way to 
detect the right register and the needed values automatically…

kind regards,
--peter
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