Messages in this thread | | | Subject | Re: [PATCH] [9/50] mmc: Added quirks for Ricoh 1180:e823 lower base clock | From | matsumur@nts ... | Date | Fri, 29 Jul 2011 11:10:45 +0900 |
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Hi Chris,
> Do you know of a better solution than always lowering the clock speed to > 50MHz for this controller?
Yes, it is a better solution. As you know, SD ver.1.1 and 2.0(SDHC) cards can be applied 50MHz SD-CLK.. SD 3.0 (UHS-I) cards also can be applied 50Mhz. However UHS-I cards are available 200 or 100Mhz SD-CLK. I would like to know if the current SD Host driver has the function of setting SD-CLK to 200Mhz for SD ver3.0 compliant Host Controller.
Thanks,
Koji Matsumuro Ricoh Company,Ltd.
Chris Ball <cjb@laptop.org> wrote on 2011/07/29 09:47:53:
> Hi,
> On Thu, Jul 28 2011, Andi Kleen wrote: > > On Fri, Jul 29, 2011 at 09:27:56AM +0900, matsumur@nts.ricoh.co.jp wrote: > >> Dear Sir, > >> > >> Ricoh 1180:e823 device is named R5U220/R5U232 (2 devices have the same > >> device ID ). > >> So, I think it should be declared to as PCI_DEVICE_ID_RICOH_R5U220. > > > > Is that just the wrong name or will it actually cause misfunction?
> I don't think it could possibly cause misfunction; it's just a macro name.
> > BTW, does anyone know whether the current SDHCI-driver sets 200Mhz to > > SD-CLK for UHS-I cards ?
> The Linux 3.1 SD driver will set the SD-CLK to 50MHz for every card on an > e823 device, and older kernels will do so too once the commit has been > applied to the stable trees. See this commit:
> http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git; > a=commitdiff;h=15bed0f2fa8e1d7db201692532c210a7823d2d21
> Do you know of a better solution than always lowering the clock speed to > 50MHz for this controller?
> Thanks,
> - Chris. > -- > Chris Ball <cjb@laptop.org> <http://printf.net/> > One Laptop Per Child
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