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unrecognised EXT_CSD revision 6解决办法
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我是在編譯了3.0內核后發現eMMC卡怎么也初始化不了，老提示這個錯誤。但正常的SD卡確可以使用，經過一番研究，在結合網上查找的資料，終于將問題解決了。
在網上搜到的資料，說明了內核對eMMC4.5的支持方法：
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mmc:?core:?Detect?eMMC?v4.5?ext_csd?entries?? ?? Gitweb:?????http://git.kernel.org/linus/38ca285044be88a0fb47b6eb91deeeb729435fd0?? Commit:?????38ca285044be88a0fb47b6eb91deeeb729435fd0?? Parent:?????d5a5bd1c3f7e8d010393530d60df8da75218a488?? Author:?????Kyungmin?Park?<kyungmin.park?<at>?samsung.com>?? AuthorDate:?Tue?Jul?26?17:12:37?2011?+0900?? Committer:??Chris?Ball?<cjb?<at>?laptop.org>?? CommitDate:?Sat?Aug?13?14:50:22?2011?-0400?? ?? ????mmc:?core:?Detect?eMMC?v4.5?ext_csd?entries?? ?? ????The?eMMC?v4.5?Spec?is?released?now:?? ?? ????EXT_CSD_REV?Extended?CSD?Revision?? ????255-7???????Reserved?? ????6???????Revision?1.6?(for?MMC?v4.5)?? ????5???????Revision?1.5?(for?MMV?v4.41)?? ????...?? ?? ????Signed-off-by:?Kyungmin?Park?<kyungmin.park?<at>?samsung.com>?? ????Signed-off-by:?Chris?Ball?<cjb?<at>?laptop.org>?? ---?? ?drivers/mmc/core/mmc.c?|????2?+-?? ?1?files?changed,?1?insertions(+),?1?deletions(-)?? ?? diff?--git?a/drivers/mmc/core/mmc.c?b/drivers/mmc/core/mmc.c?? index?aa7d1d7..5700b1c?100644?? ---?a/drivers/mmc/core/mmc.c?? +++?b/drivers/mmc/core/mmc.c?? ?<at>??<at>??-259,7?+259,7??<at>??<at>??static?int?mmc_read_ext_csd(struct?mmc_card?*card,?u8?*ext_csd)?? ????}?? ?? ????card->ext_csd.rev?=?ext_csd[EXT_CSD_REV];?? -???if?(card->ext_csd.rev?>?5)?{?? +???if?(card->ext_csd.rev?>?6)?{?? ????????printk(KERN_ERR?"%s:?unrecognised?EXT_CSD?revision?%d\n",?? ????????????mmc_hostname(card->host),?card->ext_csd.rev);?? ????????err?=?-EINVAL;?? --?? To?unsubscribe?from?this?list:?send?the?line?"unsubscribe?git-commits-head"?in?? the?body?of?a?message?to?majordomo?<at>?vger.kernel.org?? More?majordomo?info?at??http://vger.kernel.org/majordomo-info.html??
3.0的內核只支持到了eMMC-v4.41版本，對應的版本號5。
最新的eMMC-v4.5對應的版本好為6，所以程序為報錯，提示版本號6不支持。只要將版本號判斷修改為6即可。
eMMC-v5.0協議對EXT_CSD_REV定義：
額外的一段資料
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mmc:?core:?Update?the?ext-csd.rev?check?for?eMMC5.1??00/55800/5?? ?? ?? ?? authorYuvaraj?CD?<yuvaraj.cd@gmail.com>?? Tue,?21?May?2013?17:38:43?+0800?(09:38?+0000)?? committerChromeBot?<chrome-bot@google.com>?? Thu,?23?May?2013?08:57:28?+0800?(17:57?-0700)?? ?? ?? ?? With?the?new?eMMC5.1?spec,there?is?a?new?EXT_CSD?register?with?? ?? the?revision?number(EXT_CSD_REV)?7.This?patch?updates?the?check?? ?? for?ext-csd.rev?number?as?7.?? ?? ?? ?? This?patch?was?picked?from?patchwork:?? ?? ??http://patchwork.kernel.org/patch/2596591/?? ?? ?? ?? BUG=chrome-os-partner:19007?? ?? TEST=Boot?kernel?on?SMDK5420.?/wo?this?patch?emmc?gives?error?"mmc0:?? ?? ?????unrecognised?EXT_CSD?revision?7"?? ?? ?????/w?this?patch?the?above?error?is?not?seen.?? ?? ?? ?? Change-Id:?I08843976eeba6e63adc27c02365f71f8d4dc6fa0?? ?? Signed-off-by:?Alim?Akhtar?<alim.akthar@samsung.com>?? ?? Signed-off-by:?Yuvaraj?Kumar?C?D?<yuvaraj.cd@samsung.com>?? ?? Signed-off-by:?Doug?Anderson?<dianders@chromium.org>?? ?? Reviewed-on:?https://gerrit.chromium.org/gerrit/55800?? ?? ?? ?? ?? ?? ?? ?? ?? drivers/mmc/core/mmc.c?? ?? patch?|?blob?|?blame?|?history?? ?? ?? ?? ?? ?? ?? diff?--git?a/drivers/mmc/core/mmc.c?b/drivers/mmc/core/mmc.c?? ?? index?089e8ea..66b996f?100644?(file)?? ?? ?? ---?a/drivers/mmc/core/mmc.c?? +++?b/drivers/mmc/core/mmc.c?? @@?-292,7?+292,7?@@?static?int?mmc_read_ext_csd(struct?mmc_card?*card,?u8?*ext_csd)?? ????????}?? ??? ????????card->ext_csd.rev?=?ext_csd[EXT_CSD_REV];?? -???????if?(card->ext_csd.rev?>?6)?{?? +???????if?(card->ext_csd.rev?>?7)?{?? ????????????????pr_err("%s:?unrecognised?EXT_CSD?revision?%d\n",?? ????????????????????????mmc_hostname(card->host),?card->ext_csd.rev);?? ????????????????err?=?-EINVAL;??
更是牛人，這個是在chromium.org網站有人提交的補丁，使chromiumos支持eMMC-v5.1。
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