1. 07 12月, 2012 1 次提交
  2. 12 1月, 2012 2 次提交
    • S
      mmc: core: Fixup delayed work clock gating patch · 4137e504
      Stephen Boyd 提交于
      c31b50e (mmc: core: Use delayed work in clock gating framework,
      2011-11-14) missed a few things during review:
      
       o A useless pr_info()
      
       o milliseconds was written as two words
      
       o The sysfs file had units in its output
      
      Fix all three problems.
      Signed-off-by: NStephen Boyd <sboyd@codeaurora.org>
      Cc: Sujit Reddy Thumma <sthumma@codeaurora.org>
      Signed-off-by: NChris Ball <cjb@laptop.org>
      4137e504
    • S
      mmc: core: Use delayed work in clock gating framework · 597dd9d7
      Sujit Reddy Thumma 提交于
      Current clock gating framework disables the MCI clock as soon as the
      request is completed and enables it when a request arrives. This aggressive
      clock gating framework, when enabled, cause following issues:
      
      When there are back-to-back requests from the Queue layer, we unnecessarily
      end up disabling and enabling the clocks between these requests since 8MCLK
      clock cycles is a very short duration compared to the time delay between
      back to back requests reaching the MMC layer. This overhead can effect the
      overall performance depending on how long the clock enable and disable
      calls take which is platform dependent. For example on some platforms we
      can have clock control not on the local processor, but on a different
      subsystem and the time taken to perform the clock enable/disable can add
      significant overhead.
      
      Also if the host controller driver decides to disable the host clock too
      when mmc_set_ios function is called with ios.clock=0, it adds additional
      delay and it is highly possible that the next request had already arrived
      and unnecessarily blocked in enabling the clocks. This is seen frequently
      when the processor is executing at high speeds and in multi-core platforms
      thus reduces the overall throughput compared to if clock gating is
      disabled.
      
      Fix this by delaying turning off the clocks by posting request on
      delayed workqueue. Also cancel the unscheduled pending work, if any,
      when there is access to card.
      
      sysfs entry is provided to tune the delay as needed, default
      value set to 200ms.
      Signed-off-by: NSujit Reddy Thumma <sthumma@codeaurora.org>
      Acked-by: NLinus Walleij <linus.walleij@linaro.org>
      Signed-off-by: NChris Ball <cjb@laptop.org>
      597dd9d7
  3. 25 5月, 2011 1 次提交
  4. 12 8月, 2010 1 次提交
    • A
      mmc: add erase, secure erase, trim and secure trim operations · dfe86cba
      Adrian Hunter 提交于
      SD/MMC cards tend to support an erase operation.  In addition, eMMC v4.4
      cards can support secure erase, trim and secure trim operations that are
      all variants of the basic erase command.
      
      SD/MMC device attributes "erase_size" and "preferred_erase_size" have been
      added.
      
      "erase_size" is the minimum size, in bytes, of an erase operation.  For
      MMC, "erase_size" is the erase group size reported by the card.  Note that
      "erase_size" does not apply to trim or secure trim operations where the
      minimum size is always one 512 byte sector.  For SD, "erase_size" is 512
      if the card is block-addressed, 0 otherwise.
      
      SD/MMC cards can erase an arbitrarily large area up to and
      including the whole card.  When erasing a large area it may
      be desirable to do it in smaller chunks for three reasons:
      
          1. A single erase command will make all other I/O on the card
             wait.  This is not a problem if the whole card is being erased, but
             erasing one partition will make I/O for another partition on the
             same card wait for the duration of the erase - which could be a
             several minutes.
      
          2. To be able to inform the user of erase progress.
      
          3. The erase timeout becomes too large to be very useful.
             Because the erase timeout contains a margin which is multiplied by
             the size of the erase area, the value can end up being several
             minutes for large areas.
      
      "erase_size" is not the most efficient unit to erase (especially for SD
      where it is just one sector), hence "preferred_erase_size" provides a good
      chunk size for erasing large areas.
      
      For MMC, "preferred_erase_size" is the high-capacity erase size if a card
      specifies one, otherwise it is based on the capacity of the card.
      
      For SD, "preferred_erase_size" is the allocation unit size specified by
      the card.
      
      "preferred_erase_size" is in bytes.
      Signed-off-by: NAdrian Hunter <adrian.hunter@nokia.com>
      Acked-by: NJens Axboe <axboe@kernel.dk>
      Cc: Kyungmin Park <kmpark@infradead.org>
      Cc: Madhusudhan Chikkature <madhu.cr@ti.com>
      Cc: Christoph Hellwig <hch@lst.de>
      Cc: Ben Gardiner <bengardiner@nanometrics.ca>
      Cc: <linux-mmc@vger.kernel.org>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      dfe86cba