Messages in this thread | | | Date | Tue, 28 Apr 2009 21:49:47 +0200 | From | Pierre Ossman <> | Subject | Re: [Patch 1/1 v5] via-sdmmc: VIA MSP card reader driver support |
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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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