platform, pnp and mmc bus

[Pierre Ossman]

David Zeuthen wrote:

>On Sat, 2005-01-29 at 02:00 +0100, Pierre Ossman wrote:
>  
>
>>I'm trying to make the necessary additions to HAL to allow it to detect 
>>mmc cards. This has proven to be a bit more work than I first thought.
>>
>>    
>>
>
>I'm not sure exactly what you mean by mmc cards? Can you clarify a bit
>more?
>
>  
>
Most laptops today include a card reader of some sort. In most cases 
these are for SD/MMC cards. For some reason they rarely choose to put in 
a card reader with an USB interface or something similar (i.e. 
standardised). Instead the put in a controller which gives direct access 
to the SD/MMC bus. Hardware detected on this bus (i.e. the memory cards) 
are given their own device nodes in linux and put under /sys/bus/mmc the 
same way all hardware is.

>>Step 3:
>>
>>Create a pnp bus handler.
>>    
>>
>
>This already exists on HEAD.
>
>  
>
Goodie. I'll do a checkout of that then.

>>Now for the actual questions. So far I've just been playing around to 
>>get my stuff working and it's a bit of a mess. Has anyone looked at 
>>these problems and perhaps already has a plan for handling them? 
>>Otherwise I could continue working on it and get a more clean version.
>>
>>The pnp is also a problem. It doesn't really correspond to a physical 
>>bus (platform doesn't really either, but it's closer at least). But pnp 
>>devices are in every case I can think of, devices that belong on the 
>>platform bus. So should the pnp bus be a seperate bus in hal or should 
>>we try to group it with the platform bus?
>>
>>    
>>
>
>Not sure until I understand the problem domain yet. Can you possibly
>post
>the output of 'tree /sys' and describe how it works today?
>
>  
>
My point was that PNP isn't a physical bus. The devices located on what 
linux calls the PNP bus might be physically connected to ISA, LPC or 
something else. I figured that the point of HAL was to isolate 
applications from how the kernel is designed.  Sorting devices by 
physical connection seemed to be the logical choice then.

Rgds
Pierre

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