Adrian, Thank you for the feedback. I have amended the patch. I tested the patch against mmc4.3 or earlier cards and it works. Your comment about the switch boot config not being supported by earlier cards is handled by NOT checking for any errors. The reason the patch is needed is because when our boot loader gets loaded from the private boot area, it sets the partition to the private boot area and then hands control to a secondary loader. Normally our boot loader would disable access to the partition once boot code was loaded in before passing control to linux but if the process is stopped or the kernel is loaded from another device the partition number is not reset. We can fix this but it seems good practice for linux to reset the flash to a normal state. The other concerns I believe were addressed earlier. The trace showing what was happening with and without the patch. regards, Philip signed-off-by: Philip Rakity <prakity@xxxxxxxxxxx> diff -ru linux-2.6.32.8/drivers/mmc/core/mmc.c linux-2.6.32.8 copy/drivers/mmc/core/mmc.c --- linux-2.6.32.8/drivers/mmc/core/mmc.c 2010-02-09 04:57:19.000000000 -0800 +++ linux-2.6.32.8 copy/drivers/mmc/core/mmc.c 2010-03-12 20:56:16.000000000 -0800 @@ -430,6 +432,13 @@ } /* + * ensure eMMC private booting PARTITION is not enabled + */ + mmc_switch(card, EXT_CSD_CMD_SET_NORMAL, + EXT_CSD_BOOT_CONFIG, 0x0); + + /* * Compute bus speed. */ max_dtr = (unsigned int)-1; diff -ru linux-2.6.32.8/include/linux/mmc/mmc.h linux-2.6.32.8 copy/include/linux/mmc/mmc.h --- linux-2.6.32.8/include/linux/mmc/mmc.h 2010-02-09 04:57:19.000000000 -0800 +++ linux-2.6.32.8 copy/include/linux/mmc/mmc.h 2010-03-12 20:53:48.000000000 -0800 @@ -251,6 +252,7 @@ * EXT_CSD fields */ +#define EXT_CSD_BOOT_CONFIG 179 /* R/W */ #define EXT_CSD_BUS_WIDTH 183 /* R/W */ #define EXT_CSD_HS_TIMING 185 /* R/W */ #define EXT_CSD_CARD_TYPE 196 /* RO */ On Mar 15, 2010, at 1:08 AM, Adrian Hunter wrote: > Philip Rakity wrote: >> Some eMMC chips have a boot partition that is meant to be used to load in low level boot code. >> This partition is available when the chip is powered up. Normally the boot loader would disable >> access to the partition once boot code was loaded in before passing control to linux. >> >> if booting occurs from another device (not the eMMC chip) the partition will not be disabled by >> the boot loader and control will be passed to linux. This will cause linux to not recognize user >> partitions on the chip unless access to the boot partition is deactivated. >> >> See JEDEC Standard 84-A44 (eMMC 4.4 spec) -- Page 139 > > Page 139 doesn't say anything about why you need that switch command. > Please provide a more useful reference or delete this. > > Boot mode is terminated by CMD1, so that switch command should not > be needed. Please explain why it is needed in more detail. > > That switch command should not be used for devices that do not > support it e.g. eMMC 4.3 and before. > > >> >> signed off by: Philip Rakity <prakity@xxxxxxxxxxx> >> diff -ru linux-2.6.32.8/drivers/mmc/core/mmc.c linux-2.6.32.8 copy/drivers/mmc/core/mmc.c >> --- linux-2.6.32.8/drivers/mmc/core/mmc.c 2010-02-09 04:57:19.000000000 -0800 >> +++ linux-2.6.32.8 copy/drivers/mmc/core/mmc.c 2010-03-12 20:56:16.000000000 -0800 >> @@ -430,6 +432,13 @@ >> } >> >> /* >> + * ensure eMMC private booting PARTITION is not enabled >> + * see JEDEC Standard No. 84-A44 - Page 139 >> + */ >> + mmc_switch(card, EXT_CSD_CMD_SET_NORMAL, >> + EXT_CSD_BOOT_CONFIG, 0x0); >> + >> + /* >> * Compute bus speed. >> */ >> max_dtr = (unsigned int)-1; >> diff -ru linux-2.6.32.8/include/linux/mmc/mmc.h linux-2.6.32.8 copy/include/linux/mmc/mmc.h >> --- linux-2.6.32.8/include/linux/mmc/mmc.h 2010-02-09 04:57:19.000000000 -0800 >> +++ linux-2.6.32.8 copy/include/linux/mmc/mmc.h 2010-03-12 20:53:48.000000000 -0800 >> @@ -251,6 +252,7 @@ >> * EXT_CSD fields >> */ >> >> +#define EXT_CSD_BOOT_CONFIG 179 /* R/W */ >> #define EXT_CSD_BUS_WIDTH 183 /* R/W */ >> #define EXT_CSD_HS_TIMING 185 /* R/W */ >> #define EXT_CSD_CARD_TYPE 196 /* RO */ >> >> -- >> 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 >> >
signed-off-by: Philip Rakity <prakity@xxxxxxxxxxx> diff -ru linux-2.6.32.8/drivers/mmc/core/mmc.c linux-2.6.32.8 copy/drivers/mmc/core/mmc.c --- linux-2.6.32.8/drivers/mmc/core/mmc.c 2010-02-09 04:57:19.000000000 -0800 +++ linux-2.6.32.8 copy/drivers/mmc/core/mmc.c 2010-03-12 20:56:16.000000000 -0800 @@ -430,6 +432,13 @@ } /* + * ensure eMMC private booting PARTITION is not enabled + */ + mmc_switch(card, EXT_CSD_CMD_SET_NORMAL, + EXT_CSD_BOOT_CONFIG, 0x0); + + /* * Compute bus speed. */ max_dtr = (unsigned int)-1; diff -ru linux-2.6.32.8/include/linux/mmc/mmc.h linux-2.6.32.8 copy/include/linux/mmc/mmc.h --- linux-2.6.32.8/include/linux/mmc/mmc.h 2010-02-09 04:57:19.000000000 -0800 +++ linux-2.6.32.8 copy/include/linux/mmc/mmc.h 2010-03-12 20:53:48.000000000 -0800 @@ -251,6 +252,7 @@ * EXT_CSD fields */ +#define EXT_CSD_BOOT_CONFIG 179 /* R/W */ #define EXT_CSD_BUS_WIDTH 183 /* R/W */ #define EXT_CSD_HS_TIMING 185 /* R/W */ #define EXT_CSD_CARD_TYPE 196 /* RO */
