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SubjectRe: [Patch 1/1 v5] via-sdmmc: VIA MSP card reader driver support
On Wed, 22 Apr 2009 01:35:29 +0800
JosephChan@via.com.tw wrote:

> -----Original Message-----
> From: Pierre Ossman [mailto:drzeus-mmc@drzeus.cx]
> >> + else if (ios->clock >= 5000000)
> >> + clock = PCI_CLK_8M;
> >>+ else
> >>+ clock = PCI_CLK_375K;
> >>+
>
> > This looks a bit strange. Why are you not comparing with the clock frequency you'll be setting?
>
> Do you mean that we should check the current clock frequency before setting?

No. My point was that you compare with, for example, 5 MHz, but then
you set the clock to 8 MHz. This is very dangerous as you'll most
likely overclock things.


>
> > You also need to set the bits stating if the controller supports the high-speed SD and/or MMC mode, otherwise the core won't go over 25/20 MHz.
>
>
> OK, we will add the following line in the via_init_mmc_host function:
>
> mmc->caps |= MMC_CAP_MMC_HIGHSPEED |MMC_CAP_SD_HIGHSPEED;
>

You sure the controller handles MMC high-speed timings though? They are
different from SD high-speed, which is why there are two separate caps
bits.

Rgds
--
-- Pierre Ossman

Linux kernel, MMC maintainer http://www.kernel.org
rdesktop, core developer http://www.rdesktop.org
TigerVNC, core developer http://www.tigervnc.org

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