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.
TI OMAP controllers which will return the reset-in-progress bit as zero if
you read the status register too fast after setting the reset bit.
The zero is apparently from a stale snapshot of the internal state presented
in the interface register, and leads to a false indication that the reset
is complete when it either hasn't started yet or is in-progress. The
workaround is to first loop until the bit is seen as asserted, then do the
normal loop waiting to see it de-asserted.
Submitted by: Michal Meloun <meloun@miracle.cz>
- Static'ize sdhci_debug local to sdhci.c.
- Const'ify PCI device description strings.
- Nuke redundant resource ID members from sdhci_pci_softc.
- Nuke unused hw.sdhci_pci.debug tunable.
- Add support for using MSI instead of INTx, controllable via the tunable
hw.sdhci.enable_msi (defaulting to on) and tested with a RICOH R5CE823 SD
controller.
- Use NULL instead of 0 for pointers.
MFC after: 3 days
If the hardware is not in a good state (like maybe clocks aren't running
because of a configuration glitch) its timeout clock may also not work
correctly, and the next command sent will hang that thread forever. The
thread in question is usually the one and only thread (at init time) or
a bio queue worker thread whose lockup will eventually lead to the whole
system locking up when it runs out of buffers.
No sd card command should take longer than 250ms. This new code establishes
a 1-second timeout to allow plenty of safety margin over that.
the response bits the way we do in software. While the hardware is just
doing the sensible thing rather than leaving it to the software, it's in
violation of the spec by doing so. Grrrr.
In order to use platorm backend hardware driver should
impement three methods:
- platform_start_transfer and platform_finish_transfer
to start and finish transfer
- platform_will_handle - check whether transaction is
suitable for backend. If not - driver will fall back
to PIO mode.
Submitted by: Daisuke Aoyama <aoyama at peach.ne.jp>
Approved by: ian@
- Replace divisor numbers with more descirptive names
- Properly calculate minimum frequency for SDHCI 3.0
- Properly calculate frequency for SDHCI 3.0 in mmcbr_set_clock
- Add min_freq method to sdhci_if.m and provide default
implementation. By re-implementing this method hardware
drivers can control frequency controller operates when
executing initialization sequence
sdchi encapsulates a generic SD Host Controller logic that relies on
actual hardware driver for register access.
sdhci_pci implements driver for PCI SDHC controllers using new SDHCI
interface
No kernel config modifications are required, but if you load sdhc
as a module you must switch to sdhci_pci instead.
Driver supports PCI devices with class 8 and subclass 5 according to
SD Host Controller Specification.
Update NOTES, enable module and static build.
Enable related mmc and mmcsd modules build.
Discussed on: mobile@, current@