The SD path never performs the CMD6 switch its eMMC counterpart has
performed for years, so an SD card is left in default speed and every
host clocked accordingly, at 25MHz rather than the 50MHz the card
supports. A TODO in this file has asked for it since 2010; this removes
it.
A host asks for the switch by reporting SDIO_CAPS_SD_HS_MODE, which
mirrors the eMMC capability beside it. The switch is attempted once the
bus is at the default transfer rate and the wide bus is selected, and
the card's own answer decides the outcome: the 64 byte status block
reports the function actually selected, and a card that cannot do what
was asked says so there rather than failing the command. Cards below
version 1.10 of the physical layer specification are not asked, since
CMD6 postdates them.
Only a confirmed switch reaches the host, as the new
CLOCK_SD_TRANSFER_4BIT_HS rate. That is a rate rather than a flag on an
existing one because the host is clocked twice during initialization,
once before the switch can have happened, and a host that cannot tell
the two apart would run a card in default speed past its rated 25MHz.
The enumerator is added last, so no existing driver's switch statement
changes meaning, and the rate reaches only a host that reported the new
capability, which none in tree does.
Every failure path is survivable: a card that declines, a card too old
to ask, and a host that never asks all stay at the default rate.
Documents the two capabilities and the clock rates a lower half has to
handle.
The MMC/SD documentation was three sentences and a pointer to the SDIO
page, so it said nothing about how a card is registered, how the bus width
and clock are negotiated, or what any of the configuration options do. It
now covers those, the ioctl interface and /proc/mmcsd, and the high speed
switch this commit adds is described where somebody looking for it would
look rather than only in the SDIO lower half page.
Assisted-by: Claude:claude-opus-5
Signed-off-by: Justin Hammond <justin@dynam.ac>
When the CONFIG_MMCSD_MMCSUPPORT is disabled, we can remove the
mmc partition support, saving ~300+ bytes of flash on a 32-bit Arm
target. These partitions don't exist on SD cards.
Signed-off-by: Jukka Laitinen <jukka.laitinen@tii.ae>
debug.h is a NuttX-specific, non-POSIX header. Placing it in the
top-level include/ directory creates naming conflicts with external
projects that define their own debug.h.
This commit moves the canonical header to include/nuttx/debug.h,
following the NuttX convention for non-POSIX/non-standard headers,
and updates all in-tree references.
A backward-compatibility shim is left at include/debug.h that
emits a deprecation #warning and re-includes <nuttx/debug.h>,
allowing out-of-tree code to continue building while migrating.
Signed-off-by: Piyush Patle <piyushpatle228@gmail.com>
Most tools used for compliance and SBOM generation use SPDX identifiers
This change brings us a step closer to an easy SBOM generation.
Signed-off-by: Alin Jerpelea <alin.jerpelea@sony.com>
According to the eMMC specification, in Backwards Compatibility
with legacy MMC card mode, the frequency of the SD clock must be
0-26 MHZ; in high speed SDR mode, it must be 0-52MHZ. So we should
switch to high speed SDR mode if the clock frequency is higher than
26MHZ.
Signed-off-by: Yinzhe Wu <Yinzhe.Wu@sony.com>
Reviewed-by: Yuezhang Mo <Yuezhang.Mo@sony.com>
Reviewed-by: Jacky Cao <Jacky.Cao@sony.com>
Tested-by: Yinzhe Wu <Yinzhe.Wu@sony.com>
