This doesn't actually change any behavior, because it just allows a 16-bit
read of the command register to return the correct value, and nothing
actually does a 16-bit read of that register.
sdhci controllers, such as the one on a Raspberry Pi, mishandle the signal
timing in high speed signaling mode, but run just fine in standard mode
with the bus running at frequencies between 25-50MHz (which shouldn't work).
This is the solution adopted by U-Boot and other OSes (linux and *BSD)
for the timeouts on Raspberry Pi boards with certain SD cards. Some
research shows that this quirk is also used on a few other boards, so the
fix is a generic quirk instead of being in the RPi-specific driver code.
This change is based on information discovered by Michal Meloun.
The driver inherently does dma in 512 byte chunks, but it's possible that
such a buffer can span two physically discontiguous pages (such as when
a userland program does IO on the raw /dev/mmcsdN devices). Now the driver
can handle a buffer that's split across two pages.
It could in theory handle any number of segments now, but as long as IO is
being done in 512 byte blocks it will never need more than two.
requires that each 512 byte IO be in a single contiguous buffer, but if a
buffer crosses a page boundary and the physical pages aren't contiguous
you can get an EFBIG failure (too many segments).
The driver really should handle multiple segment IO, but before adding that
I wanted to make sure that it's handling failure properly while the failure
is easily recreatable.
that expose new bugs with HS mode.
When the old code could not do the proper card detection it would boot with
lower defaults (and no HS mode) and this makes some HS cards boots.
Now, with the card always identified as HS capable, the sdhci controller
tries to run the card at HS speeds and makes the boot always fail.
Disable the HS mode for now (which still can be enabled with the tunable)
until it is properly fixed.
MFC with: r273264
Requested by: many
lose the contents of consecutive writes (that happens within two SD card
clock cycles).
This fixes the causes of instability during the SD card detection and
identification on Raspberry Pi (which happens at 400 kHz and so was much
more vulnerable to this issue).
Remove the previous workaround which clearly can't provide the same effect.
MFC after: 1 week
Relnotes: yes
to check the status property in their probe routines.
Simplebus used to only instantiate its children whose status="okay"
but that was improper behavior, fixed in r261352. Now that it doesn't
check anymore and probes all its children; the children all have to
do the check because really only the children know how to properly
interpret their status property strings.
Right now all existing drivers only understand "okay" versus something-
that's-not-okay, so they all use the new ofw_bus_status_okay() helper.
really need it. That would be almost everywhere it was included. Add
it in a couple files that really do need it and were previously getting
it by accident via another header.
register from a bus space resource.
Note that this macro is just for ARM, and is intended to have a short
lifespan. The DMA engines in some SoCs need the physical address of a
memory-mapped device register as one of the arguments for the transfer.
Several scattered ad-hoc solutions have been converted to use this macro,
which now also serves to mark the places where a more complete fix needs
to be applied (after that fix has been designed).
seems to cause more problems then previous behavior: it either breaks
initilization sequence in other places or uncovers problems with
high-speed mode timing for SDHCI 3.0
SDHCI driver
Suggested by: Daisuke Aoyama
- Set initilization sequence frequency to 8MHz. It should fix Data CRC
errors. Standard requires initialization sequence to be executed
at 400KHz but on this hardware low frequncies seems to cause
Data CRC errors.
Value was derived from analyzing hardware signals after
Raspberry Pi is powered up. Before any data is read though DATA line
adapter's clock frequency is changed to 8MHz.
Modern cards should function fine at 8MHz but for older MMC cards it
can be overriden by setting hw.bcm2835.sdhci.min_freq tunable.
