98ccf14909
Some hosts cannot do scatter/gather in hardware. Since not doing sg is such a big performance hit, we (optionally) bounce the requests to a simple linear buffer that we hand over to the driver. Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>
35 lines
954 B
Plaintext
35 lines
954 B
Plaintext
#
|
|
# MMC/SD card drivers
|
|
#
|
|
|
|
comment "MMC/SD Card Drivers"
|
|
|
|
config MMC_BLOCK
|
|
tristate "MMC block device driver"
|
|
depends on BLOCK
|
|
default y
|
|
help
|
|
Say Y here to enable the MMC block device driver support.
|
|
This provides a block device driver, which you can use to
|
|
mount the filesystem. Almost everyone wishing MMC support
|
|
should say Y or M here.
|
|
|
|
config MMC_BLOCK_BOUNCE
|
|
bool "Use bounce buffer for simple hosts"
|
|
depends on MMC_BLOCK
|
|
default y
|
|
help
|
|
SD/MMC is a high latency protocol where it is crucial to
|
|
send large requests in order to get high performance. Many
|
|
controllers, however, are restricted to continuous memory
|
|
(i.e. they can't do scatter-gather), something the kernel
|
|
rarely can provide.
|
|
|
|
Say Y here to help these restricted hosts by bouncing
|
|
requests back and forth from a large buffer. You will get
|
|
a big performance gain at the cost of up to 64 KiB of
|
|
physical memory.
|
|
|
|
If unsure, say Y here.
|
|
|