Re: [patch 1/5] Staging: VME Framework for the Linux Kernel

From: Martyn Welch
Date: Tue Aug 11 2009 - 12:37:48 EST


Emilio G. Cota wrote:
Martyn Welch wrote:
It wouldn't break it, the model simply couldn't give you more
than 8 windows-->8 devices.
Unless the devices we the same and the driver reused one window.

No, we agreed on that devices should know *nothing* about windows.

Don't think I did. :-)

I agreed that it would be impossible to assign sole use of 8 resources to 17 different drivers. I feel that there could be room and indeed a need for both approaches. It may be more efficient for a driver to use and move 1 window to position it's self over the registers of each of a number of compatible devices as required. Such a driver could exist side-by-side with drivers using your approach, that utilize a layer which removes such control. Whilst I understand you can assign a fairly sizable chunk of memory mapped IO for VME, this is not always the case. In situations where the available memory mapped IO is limited, placing a large window to cover 2 smaller windows with dead space in between them will not be an adequate solution either.

Martyn
E.


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