92 lines
3.3 KiB
ReStructuredText
92 lines
3.3 KiB
ReStructuredText
|
==================================
|
||
|
|
SD and MMC Block Device Attributes
|
||
|
|
==================================
|
||
|
|
|
||
|
|
These attributes are defined for the block devices associated with the
|
||
|
|
SD or MMC device.
|
||
|
|
|
||
|
|
The following attributes are read/write.
|
||
|
|
|
||
|
|
======== ===============================================
|
||
|
|
force_ro Enforce read-only access even if write protect switch is off.
|
||
|
|
======== ===============================================
|
||
|
|
|
||
|
|
SD and MMC Device Attributes
|
||
|
|
============================
|
||
|
|
|
||
|
|
All attributes are read-only.
|
||
|
|
|
||
|
|
====================== ===============================================
|
||
|
|
cid Card Identification Register
|
||
|
|
csd Card Specific Data Register
|
||
|
|
scr SD Card Configuration Register (SD only)
|
||
|
|
date Manufacturing Date (from CID Register)
|
||
|
|
fwrev Firmware/Product Revision (from CID Register)
|
||
|
|
(SD and MMCv1 only)
|
||
|
|
hwrev Hardware/Product Revision (from CID Register)
|
||
|
|
(SD and MMCv1 only)
|
||
|
|
manfid Manufacturer ID (from CID Register)
|
||
|
|
name Product Name (from CID Register)
|
||
|
|
oemid OEM/Application ID (from CID Register)
|
||
|
|
prv Product Revision (from CID Register)
|
||
|
|
(SD and MMCv4 only)
|
||
|
|
serial Product Serial Number (from CID Register)
|
||
|
|
erase_size Erase group size
|
||
|
|
preferred_erase_size Preferred erase size
|
||
|
|
raw_rpmb_size_mult RPMB partition size
|
||
|
|
rel_sectors Reliable write sector count
|
||
|
|
ocr Operation Conditions Register
|
||
|
|
dsr Driver Stage Register
|
||
|
|
cmdq_en Command Queue enabled:
|
||
|
|
|
||
|
|
1 => enabled, 0 => not enabled
|
||
|
|
====================== ===============================================
|
||
|
|
|
||
|
|
Note on Erase Size and Preferred Erase Size:
|
||
|
|
|
||
|
|
"erase_size" is the minimum size, in bytes, of an erase
|
||
|
|
operation. For MMC, "erase_size" is the erase group size
|
||
|
|
reported by the card. Note that "erase_size" does not apply
|
||
|
|
to trim or secure trim operations where the minimum size is
|
||
|
|
always one 512 byte sector. For SD, "erase_size" is 512
|
||
|
|
if the card is block-addressed, 0 otherwise.
|
||
|
|
|
||
|
|
SD/MMC cards can erase an arbitrarily large area up to and
|
||
|
|
including the whole card. When erasing a large area it may
|
||
|
|
be desirable to do it in smaller chunks for three reasons:
|
||
|
|
|
||
|
|
1. A single erase command will make all other I/O on
|
||
|
|
the card wait. This is not a problem if the whole card
|
||
|
|
is being erased, but erasing one partition will make
|
||
|
|
I/O for another partition on the same card wait for the
|
||
|
|
duration of the erase - which could be a several
|
||
|
|
minutes.
|
||
|
|
2. To be able to inform the user of erase progress.
|
||
|
|
3. The erase timeout becomes too large to be very
|
||
|
|
useful. Because the erase timeout contains a margin
|
||
|
|
which is multiplied by the size of the erase area,
|
||
|
|
the value can end up being several minutes for large
|
||
|
|
areas.
|
||
|
|
|
||
|
|
"erase_size" is not the most efficient unit to erase
|
||
|
|
(especially for SD where it is just one sector),
|
||
|
|
hence "preferred_erase_size" provides a good chunk
|
||
|
|
size for erasing large areas.
|
||
|
|
|
||
|
|
For MMC, "preferred_erase_size" is the high-capacity
|
||
|
|
erase size if a card specifies one, otherwise it is
|
||
|
|
based on the capacity of the card.
|
||
|
|
|
||
|
|
For SD, "preferred_erase_size" is the allocation unit
|
||
|
|
size specified by the card.
|
||
|
|
|
||
|
|
"preferred_erase_size" is in bytes.
|
||
|
|
|
||
|
|
Note on raw_rpmb_size_mult:
|
||
|
|
|
||
|
|
"raw_rpmb_size_mult" is a multiple of 128kB block.
|
||
|
|
|
||
|
|
RPMB size in byte is calculated by using the following equation:
|
||
|
|
|
||
|
|
RPMB partition size = 128kB x raw_rpmb_size_mult
|