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  1. 05 Oct, 2008 7 commits
    • Haavard Skinnemoen's avatar
      atmel-mci: Don't overwrite error bits when NOTBUSY is set · ca55f46e
      Haavard Skinnemoen authored 
      After a data error, we wait for the NOTBUSY bit to be set so that we can
be sure the data transfer is completely finished. However, when NOTBUSY
is set, the interrupt handler copies the contents of SR into
data_status, overwriting any error bits we may have detected earlier.

To avoid this, initialize data_status to 0 before starting a request, and
don't overwrite it unless it still contains 0.
Signed-off-by: default avatarHaavard Skinnemoen <haavard.skinnemoen@atmel.com>
      ca55f46e
    • Haavard Skinnemoen's avatar
      atmel-mci: Add experimental DMA support · 65e8b083
      Haavard Skinnemoen authored 
      This adds support for DMA transfers through the generic DMA engine
framework with the DMA slave extensions.

The driver has been tested using mmc-block and ext3fs on several SD,
SDHC and MMC+ cards. Reads and writes work fine, with read transfer
rates up to 7.5 MiB/s on fast cards with debugging disabled.

Unfortunately, the driver has been known to lock up from time to time
with DMA enabled, so DMA support is currently optional and marked
EXPERIMENTAL. However, I didn't see any problems while testing 13
different cards (MMC, SD and SDHC of different brands and sizes), so I
suspect the "Initialize BLKR before sending data transfer command" fix
that was posted earlier fixed this as well.
Signed-off-by: default avatarHaavard Skinnemoen <haavard.skinnemoen@atmel.com>
      65e8b083
    • Haavard Skinnemoen's avatar
      atmel-mci: support multiple mmc slots · 965ebf33
      Haavard Skinnemoen authored 
      The Atmel MCI controller can drive multiple cards through separate sets
of pins, but only one at a time. This patch adds support for
multiplexing access to the controller so that multiple card slots can be
used as if they were hooked up to separate mmc controllers.

The atmel-mci driver registers each slot as a separate mmc_host. Both
access the same common controller state, but they also have some state
on their own for card detection/write protect handling, and separate
shadows of the MR and SDCR registers.

When one of the slots receives a request from the mmc core, the common
controller state is checked. If it's idle, the request is submitted
immediately. If not, the request is added to a queue. When a request is
done, the queue is checked and if there is a queued request, it is
submitted before the completion callback is called.

This patch also includes a few cleanups and fixes, including a locking
overhaul. I had to change the locking extensively in any case, so I
might as well try to get it right. The driver no longer takes any
irq-safe locks, which may or may not improve the overall system
performance.

This patch also adds a bit of documentation of the internal data
structures.
Signed-off-by: default avatarHaavard Skinnemoen <haavard.skinnemoen@atmel.com>
      965ebf33
    • Haavard Skinnemoen's avatar
      atmel-mci: Platform code for supporting multiple mmc slots · 6b918657
      Haavard Skinnemoen authored 
      Add the necessary platform infrastructure to support multiple mmc/sdcard
slots all at once through a single controller. Currently, the driver
will use the first valid slot it finds and stick with that, but later
patches will add support for switching between several slots on the fly.

Extend the platform data structure with per-slot information: MMC/SDcard
bus width and card detect/write protect pins. This will affect the pin
muxing as well as the capabilities announced to the mmc core.

Note that board code is now required to supply a mci_platform_data
struct to at32_add_device_mci().
Signed-off-by: default avatarHaavard Skinnemoen <haavard.skinnemoen@atmel.com>
      6b918657
    • Haavard Skinnemoen's avatar
      atmel-mci: Don't stop the clock between transfers · 945533b5
      Haavard Skinnemoen authored 
      Some cards might get upset if we turn off the clock for extended periods
of time. So keep the clock running until the mmc core tells us to turn
it off.

Also, don't reset the controller between each transfer. That was an
attempt to work around earlier bugs, and it never really worked very
well.
Signed-off-by: default avatarHaavard Skinnemoen <haavard.skinnemoen@atmel.com>
      945533b5
    • Haavard Skinnemoen's avatar
      atmel-mci: Implement tasklet as a state machine · c06ad258
      Haavard Skinnemoen authored 
      With the current system of completed/pending events, things may get
handled in different order depending on which event triggers first. For
example, if the data transfer is complete before the command, the stop
command must be sent after the command is complete, not the data. This
creates a bit of complexity around the stop command.

By having the tasklet go through a sequence of clearly defined states,
things always happen in a certain order even if the events come at
different times, so the stop command can simply be sent when we exit the
"sending data" state because we will never enter that state before the
command has been sent successfully.
Signed-off-by: default avatarHaavard Skinnemoen <haavard.skinnemoen@atmel.com>
      c06ad258
    • Haavard Skinnemoen's avatar
      atmel-mci: Initialize BLKR before sending data transfer command · a252e3e3
      Haavard Skinnemoen authored 
      The atmel-mci driver sometimes fails data transfers like this:

   mmcblk0: error -5 transferring data
   end_request: I/O error, dev mmcblk0, sector 2749769
   end_request: I/O error, dev mmcblk0, sector 2749777

It turns out that this might be caused by the BLKR register (which
contains the block size and the number of blocks being transfered) being
initialized too late. This patch moves the initialization of BLKR so
that it contains the correct value before the block transfer command is
sent.

This error is difficult to reproduce, but if you insert a long delay
(mdelay(10) or thereabouts) between the calls to atmci_start_command()
and atmci_submit_data(), all transfers seem to fail without this patch,
while I haven't seen any failures with this patch.
Reported-by: default avatarHein_Tibosch <hein_tibosch@yahoo.es>
Signed-off-by: default avatarHaavard Skinnemoen <haavard.skinnemoen@atmel.com>
      a252e3e3
  3. 04 Oct, 2008 16 commits
  5. 03 Oct, 2008 17 commits
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