Re: platform_driver_register() ??

From: Pierre Ossman
Date: Sun Jul 08 2007 - 08:23:38 EST


On Thu, 5 Jul 2007 14:51:35 +0530
"Midhun Agnihotram" <agnimidhun@xxxxxxxxx> wrote:

>
> Is it necessary that the firmware (may be bootloader) notify about
> the MMC host to Linux? The kernel documentation (platform.txt) says :
>
> "The firmware should notify the platform bus about devices before the
> legacy drivers have had a chance to load."
>
> Have I interpreted the above sentence correctly?
>

I don't know what the meaning of that sentence was supposed to be, but
platform devices are everything the kernel cannot probe in a "normal"
way. Usually this covers devices that cannot be probed at all, but must
be listed some other way (i.e. manually).

Commonly the arch and machine specific code adds the devices. The
machine code is usually specific to a certain hardware, so the code
"knows" which devices are present, even though it can't probe them.

So to answer your question; no, the firmware doesn't have to tell Linux
about the devices.

Rgds
--
-- Pierre Ossman

Linux kernel, MMC maintainer http://www.kernel.org
PulseAudio, core developer http://pulseaudio.org
rdesktop, core developer http://www.rdesktop.org
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