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/[email protected]/msg02307.html)? Thanks Sujit -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
