Messages in this thread | | | Date | Fri, 11 Jan 2008 01:25:01 -0500 | From | "Mike Frysinger" <> | Subject | Re: [patch] split MMC_CAP_4_BIT_DATA |
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On Jan 11, 2008 1:17 AM, Bryan Wu <cooloney.lkml@gmail.com> wrote: > On Jan 10, 2008 7:57 PM, Pierre Ossman <drzeus-mmc@drzeus.cx> wrote: > > On Thu, 10 Jan 2008 17:22:55 +0800 > > "Bryan Wu" <cooloney.lkml@gmail.com> wrote: > > > > > > > > At page 4-3 of ADSP-BF54x Blackfin(R) Processor Peripheral Hardware > > > Reference, there is a table which guide us the SDH controller does not > > > support 4-bit mode MMC card. Please found the table picture in the > > > attachment or get the document at: > > > http://www.analog.com/UploadedFiles/Associated_Docs/61460151169789ADSP_BF54x_Blackfin_Processor_Peripheral_Hardware_Reference.pdf > > > > > > > Ok, but this just means the controller wasn't designed with 4-bit MMC in mind. As several other "SD-only" controller have been tested with modern MMC cards without a problem, this is not sufficient to explain any problem. > > > > This should be some HW design issue and BF54x including SDH controller > is in mass production. > There is no chance to change the silicon, we just wanna use software > driver to workaround this issue. > So Mike's patch is here. > > > > > > > Thanks, actually we are not yet convinced by our hardware designer > > > why BF54x SDH does not support 4-bit MMC. > > > > > > > Please keep me informed on how it progresses. I'd like an at least plausible explanation, preferably also some empirical data, before I'm ready to accept Mike's patch. > > > > We were told this is an hardware design issue, so please help us to > workaround it in software side with Mike's patch. > And how do you think my suggestion to Mike's patch, > #define MMC_CAP_4_BIT_DATA ( MMC_CAP_SD_4_BIT_DATA | MMC_CAP_MMC_4_BIT_DATA) > Then no need to change other MMC host drivers
i can send an updated patch as needed. i think Bryan's suggestion here is a good one. -mike
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