mirror of
https://github.com/torvalds/linux.git
synced 2024-12-29 06:12:08 +00:00
4137e50494
c31b50e (mmc: core: Use delayed work in clock gating framework, 2011-11-14) missed a few things during review: o A useless pr_info() o milliseconds was written as two words o The sysfs file had units in its output Fix all three problems. Signed-off-by: Stephen Boyd <sboyd@codeaurora.org> Cc: Sujit Reddy Thumma <sthumma@codeaurora.org> Signed-off-by: Chris Ball <cjb@laptop.org>
77 lines
2.8 KiB
Plaintext
77 lines
2.8 KiB
Plaintext
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 Identifaction 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)
|
|
serial Product Serial Number (from CID Register)
|
|
erase_size Erase group size
|
|
preferred_erase_size Preferred erase size
|
|
|
|
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.
|
|
|
|
SD/MMC/SDIO Clock Gating Attribute
|
|
==================================
|
|
|
|
Read and write access is provided to following attribute.
|
|
This attribute appears only if CONFIG_MMC_CLKGATE is enabled.
|
|
|
|
clkgate_delay Tune the clock gating delay with desired value in milliseconds.
|
|
|
|
echo <desired delay> > /sys/class/mmc_host/mmcX/clkgate_delay
|