unrecognised EXT_CSD revision 6解决办法

我是在编译了3.0内核后发现eMMC卡怎么也初始化不了，老提示这个错误。但正常的SD卡确可以使用，经过一番研究，在结合网上查找的资料，终于将问题解决了。

在网上搜到的资料，说明了内核对eMMC4.5的支持方法：

 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;
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3.0的内核只支持到了eMMC-v4.41版本，对应的版本号5。

最新的eMMC-v4.5对应的版本好为6，所以程序为报错，提示版本号6不支持。只要将版本号判断修改为6即可。

eMMC-v5.0协议对EXT_CSD_REV定义：

额外的一段资料

 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，这个是在chromium.org网站有人提交的补丁，使chromiumos支持eMMC-v5.1。