Hi: I have not seen case (1) and (2) across >20 types of micro SD cards, and >10 types of Sandisk/Toshiba eMMC chips, so I believe the 2GB condition is ok. Probing of the OCR bit to chose between byte and sector mode will also work, which I have tried in a large scope. Regards, -Ethan On Wed, Jan 5, 2011 at 12:59 AM, Sujit Reddy <sujitreddy243@xxxxxxxxx> wrote: > Hi, > > Any comments on below mentioned query? > > Thanks > Sujit > > On Thu, Dec 23, 2010 at 1:35 PM, Sujit Reddy <sujitreddy243@xxxxxxxxx> wrote: >> Hi, >> >> According to eMMC spec v4.3, Section 6.1 says that greater than 2GB >> density cards are sector addressable and less than 2GB are byte addressable. >> But Section 7.3.3 says that OCR bit 30 needs to be used which access mode >> the host must use for all its future transactions. >> >> In mainline kernel the support for less than 2GB cards is by checking >> the density of card. >> If it is greater than 2GB it is assumed to be supporting sector addressing. >> >> But actually we need to check the OCR value to determine the correct access mode >> See patch (http://www.spinics.net/lists/linux-mmc/msg01466.html) by Philip. >> >> Some eMMC cards even though less than 2GB have SEC_COUNT value defined >> in EXT_CSD register but does not support sector access mode. >> >> I have a couple of questions here: >> 1) Are there any cards that support only byte access mode even though >> the density is >> greater than 2GB? >> 2) If there are cards which have capacity less than 2GB and supports only sector >> access mode then what's the solution? I am not sure If there are any such cards. >> >> Philip's patch handles both these scenarios effectively. >> Can anyone mention the reason not taking Philip's patch into account, >> which I feel is much >> more fool proof than the implementation in mainline kernel >> (http://www.mail-archive.com/linux-mmc@xxxxxxxxxxxxxxx/msg02307.html)? >> >> Thanks >> Sujit >> > -- > To unsubscribe from this list: send the line "unsubscribe linux-mmc" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
