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mmc: Fix size calculation for sector addressed MMC version 4

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For eMMC v4 and newer that is smaller than 2 GiB, the JEDEC JESD84-B51
section 6.2.4 Configure partitions indicates that EXT_CSD SEC_COUNT
should not be used to determine device size, and instead device size
should be calculated from C_SIZE and C_SIZE_MULT.

This is not exactly accurate, the 2 GiB limit is not a hard line,
there are eMMC devices which are smaller than 2 GiB and still
require device size to be determined from EXT_CSD SEC_COUNT. The
hard line is instead OCR HCS bit, which indicates whether the device
is byte or sector addressed, the former applies to most devices
below 2 GiB, and the later applies mostly to devices above 2 GiB.

However, there are a couple of devices which are smaller than 2 GiB
and still set the OCR HCS bit to indicate they are sector addressed,
and therefore the size calculation for those devices should also
use EXT_CSD SEC_COUNT . Use mmc->high_capacity flag to discern the
devices instead of arbitrary 2 GiB limit. The mmc->high_capacity flag
reflects the OCR HCS bit state.

Fixes: 639b7827d1 ("mmc: fix the condition for MMC version 4")
Signed-off-by: Marek Vasut <marex@denx.de>
This commit is contained in:
Marek Vasut 2025-01-29 12:15:54 +01:00 • committed by Tom Rini
parent 59fd62d71c
commit dbb9e136b8
1 changed files with 1 additions and 1 deletions
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2
drivers/mmc/mmc.c
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@ -2376,7 +2376,7 @@ static int mmc_startup_v4(struct mmc *mmc)
| ext_csd[EXT_CSD_SEC_CNT + 2] << 16
| ext_csd[EXT_CSD_SEC_CNT + 3] << 24;
capacity *= MMC_MAX_BLOCK_LEN;
if ((capacity >> 20) > 2 * 1024)
if (mmc->high_capacity)
mmc->capacity_user = capacity;
}