ARM: OMAP: MMC performance upgrade on OMAP2
A message that is not in the archive (sent off-list or not yet received): [email protected]
Hi Pierre,
If I am not wrong what you mean is,
If (card_is_4.0) then its HS {
If (it supports 26 && 52) and ur controller can generate 52 Mhzclk
then configure MMC_CLK to operate at 52Mhz
If (card supports only 26) then configure MMC_CLK at 26Mhz.
If (card can support upto 52 but controller can only support
till 48)
then configure MMC_CLK to 48 and issue a CMD4 to modify DSR (for
new
timing values).
Now this DSR timing depends on what Controller can offer and it
doesn't depend on the frequency as such. Is this what you mean?
}
Else{
Not an HS
}
Regards,
Khasim
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-----Original Message-----
From: Pierre Ossman [mailto:[email protected]]
Sent: Friday, March 09, 2007 12:20 AM
To: [email protected]
Cc: Syed Mohammed, Khasim; [email protected]
Subject: Re: [PATCH] ARM: OMAP: MMC performance upgrade on OMAP2Quoted 3 lines · Kyungmin Park
Yes, that's my understanding.
If the card is 4.0 compliant and OMAP2 supports up to 48MHz. then we
use
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this 48MHz clock.
But current mmc code down-grade to 20MHz since it's not set
highspeed.
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If the card is 4.0 compliant and even though host don't support
highspeed
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feature, we set the highspeed flags for support host max clocks. I think highspeed depends on host clock. Is it right?
No, high-speed is a _timing_ capability, not one of frequency (although
the
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new
timing allows a higher maximum frequency). Hence, maximum clock has _nothing_ to
do with what it can support. All it can tell you is that reasonably,
this
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controller should support at least one of SD or MMC high-speed, but it cannot
tell you which.Rgds
Pierre