Adding bcm2835-sdhost driver, and an overlay to enable it
BCM2835 has two SD card interfaces. This driver uses the other one.
bcm2835-sdhost: Error handling fix, and code clarification
bcm2835-sdhost: Adding overclocking option
Allow a different clock speed to be substitued for a requested 50MHz.
This option is exposed using the "overclock_50" DT parameter.
Note that the sdhost interface is restricted to integer divisions of
core_freq, and the highest sensible option for a core_freq of 250MHz
is 84 (250/3 = 83.3MHz), the next being 125 (250/2) which is much too
high.
Use at your own risk.
bcm2835-sdhost: Round up the overclock, so 62 works for 62.5Mhz
Also only warn once for each overclock setting.
bcm2835-sdhost: Improve error handling and recovery
1) Expose the hw_reset method to the MMC framework, removing many
internal calls by the driver.
2) Reduce overclock setting on error.
3) Increase timeout to cope with high capacity cards.
4) Add properties and parameters to control pio_limit and debug.
5) Reduce messages at probe time.
bcm2835-sdhost: Further improve overclock back-off
It seems that the sdhost interface returns CRC7 errors for CMD1,
which is the MMC-specific SEND_OP_COND. Returning these errors to
the MMC layer causes a downward spiral, but ignoring them seems
to be harmless.
The bcm2835-mmc driver (and -sdhost driver that copied from it)
contains code to handle SDIO interrupts in a threaded interrupt
handler rather than waking the MMC framework thread. The change
follows a patch from Russell King that adds the facility as the
preferred way of working.
However, the new code path is only present in ARCH_BCM2835
builds, which I have taken to be a way of testing the waters
rather than making the change across the board; I can't see
any technical reason why it wouldn't be enabled for MACH_BCM270X
builds. So this patch standardises on the ARCH_BCM2835 code,
removing the old code paths.
The MMC card-discovery process generates timeouts. This is
expected behaviour, so reporting it to the user serves no purpose.
Suppress the reporting of timeout errors unless the debug flag
is on.
bcm2835-sdhost: Add workaround for odd behaviour on some cards
For reasons not understood, the sdhost driver fails when reading
sectors very near the end of some SD cards. The problem could
be related to the similar issue that reading the final sector
of any card as part of a multiple read never completes, and the
workaround is an extension of the mechanism introduced to solve
that problem which ensures those sectors are always read singly.
bcm2835-sdhost: Major revision
This is a significant revision of the bcm2835-sdhost driver. It
improves on the original in a number of ways:
1) Through the use of CMD23 for reads it appears to avoid problems
reading some sectors on certain high speed cards.
2) Better atomicity to prevent crashes.
3) Higher performance.
4) Activity logging included, for easier diagnosis in the event
of a problem.
Signed-off-by: Phil Elwell <phil@raspberrypi.org>
bcm2835-sdhost: Restore ATOMIC flag to PIO sg mapping
Allocation problems have been seen in a wireless driver, and
this is the only change which might have been responsible.
SQUASH: bcm2835-sdhost: Only claim one DMA channel
With both MMC controllers enabled there are few DMA channels left. The
bcm2835-sdhost driver only uses DMA in one direction at a time, so it
doesn't need to claim two channels.
Signed-off-by: Phil Elwell <phil@raspberrypi.org>
bcm2835-sdhost: Workaround for "slow" sectors
Some cards have been seen to cause timeouts after certain sectors are
read. This workaround enforces a minimum delay between the stop after
reading one of those sectors and a subsequent data command.
Using CMD23 (SET_BLOCK_COUNT) avoids this problem, so good cards will
not be penalised by this workaround.
Signed-off-by: Phil Elwell <phil@raspberrypi.org>
bcm2835-sdhost: Firmware manages the clock divisor
The bcm2835-sdhost driver hands control of the CDIV clock divisor
register to matching firmware, allowing it to adjust to a changing
core clock. This removes the need to use the performance governor or
to enable io_is_busy on the on-demand governor in order to get the
best SD performance.
N.B. As SD clocks must be an integer divisor of the core clock, it is
possible that the SD clock for "turbo" mode can be different (even
lower) than "normal" mode.
Signed-off-by: Phil Elwell <phil@raspberrypi.org>
bcm2835-sdhost: Reset the clock in task context
Since reprogramming the clock can now involve a round-trip to the
firmware it must not be done at atomic context, and a tasklet
is not a task.
Signed-off-by: Phil Elwell <phil@raspberrypi.org>
bcm2835-sdhost: Don't exit cmd wait loop on error
The FAIL flag can be set in the CMD register before command processing
is complete, leading to spurious "failed to complete" errors. This has
the effect of promoting harmless CRC7 errors during CMD1 processing
into errors that can delay and even prevent booting.
Also:
1) Convert the last KERN_ERROR message in the register dumping to
KERN_INFO.
2) Remove an unnecessary reset call from bcm2835_sdhost_add_host.
projects / mirror_ubuntu-artful-kernel.git / commit