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Message-ID: <44F85797.9070208@drzeus.cx>
Date: Fri, 01 Sep 2006 17:53:59 +0200
From: Pierre Ossman <drzeus-list@...eus.cx>
To: Ian Stirling <ian.stirling@...ve.plus.com>
CC: madhu chikkature <crmadhu210@...il.com>,
linux-kernel@...r.kernel.org
Subject: Re: SDIO card support in Linux
Ian Stirling wrote:
>>
>> SD mandates a star topology (just a single card per bus), so we'll just
>> force a single card into the list. SD memory cards can actually work on
>> a shared bus, SDIO can not. It's not a big problem in practice though.
>
> Is this true in SD-1 bit mode, or SPI?
Yes, no. :)
> I see nothing on a quick read-through of the abbreviated SDIO spec
> precluding this.
> Of course, it'd mean wire-or'd interrupt lines.
>
The problem is that there is no "king-of-the-hill" mechanism in the SDIO
init sequence (like there is in SD mem). The protocol assumes that the
desired card always receives the command.
Rgds
Pierre
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