[U-Boot] [PATCH v2] mmc: Update "mmc->part_num" when performing a partition switch

[Stephen Warren]

On 06/04/2013 02:45 PM, Fabio Estevam wrote:
> Hi Stephen,
> 
> On Tue, Jun 4, 2013 at 4:36 PM, Stephen Warren <swarren at wwwdotorg.org> wrote:
> 
>> That seems like a reasonable way for the code to work. However, you'd
>> need to modify common/env_mmc.c:init_mmc_for_env() so that it saves off
>> mmc->part_num before switching MMC partitions, so that
>> fini_mmc_for_env() knows which partition to switch back to. Right now,
>> it relies on the fact that mmc_switch_part() does not update
>> mmc->part_num, and hence uses that value to save the previously selected
>> partition ID.
>>
>> Also, if you make this change, I think you can update
>> common/cmd_mmc.c:do_mmcops(), since it will no longer need to update
>> mmc->part_num after a successful switch.
> 
> I understood your second suggestion and did the changes below, but I
> am not sure on the first one regarding the change you proposed inside
> init_mmc_for_env().

In env_mmc.c, you'll want something like:

+#ifdef CONFIG_SYS_MMC_ENV_PART
+static char orig_part_num;
+#ifdef CONFIG_SYS_MMC_ENV_PART

 static int init_mmc_for_env(struct mmc *mmc)
 ...
 #ifdef CONFIG_SYS_MMC_ENV_PART
+	orig_part_num = mmc->part_num;
 	if (CONFIG_SYS_MMC_ENV_PART != mmc->part_num) {
 		if (mmc_switch_part(CONFIG_SYS_MMC_ENV_DEV,
 				    CONFIG_SYS_MMC_ENV_PART)) {
 			puts("MMC partition switch failed\n");
 			return -1;
 		}
 	}
 #endif
...
 static void fini_mmc_for_env(struct mmc *mmc)
 {
 #ifdef CONFIG_SYS_MMC_ENV_PART
-	if (CONFIG_SYS_MMC_ENV_PART != mmc->part_num)
+ 	if (mmc->part_num != orig_part_num)
 		mmc_switch_part(CONFIG_SYS_MMC_ENV_DEV,
-				mmc->part_num);
+				orig_part_num);
 #endif
 }