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  1. 04 Apr, 2013 29 commits
  3. 03 Apr, 2013 7 commits
  5. 02 Apr, 2013 2 commits
    • Mike Turquette's avatar
      clk: allow reentrant calls into the clk framework · 533ddeb1
      Mike Turquette authored 
      Reentrancy into the clock framework is necessary for clock operations
that result in nested calls to the clk api.  A common example is a clock
that is prepared via an i2c transaction, such as a clock inside of a
discrete audio chip or a power management IC.  The i2c subsystem itself
will use the clk api resulting in a deadlock:

clk_prepare(audio_clk)
	i2c_transfer(..)
		clk_prepare(i2c_controller_clk)

The ability to reenter the clock framework prevents this deadlock.

Other use cases exist such as allowing .set_rate callbacks to call
clk_set_parent to achieve the best rate, or to save power in certain
configurations.  Yet another example is performing pinctrl operations
from a clk_ops callback.  Calls into the pinctrl subsystem may call
clk_{un}prepare on an unrelated clock.  Allowing for nested calls to
reenter the clock framework enables both of these use cases.

Reentrancy is implemented by two global pointers that track the owner
currently holding a global lock.  One pointer tracks the owner during
sleepable, mutex-protected operations and the other one tracks the owner
during non-interruptible, spinlock-protected operations.

When the clk framework is entered we try to hold the global lock.  If it
is held we compare the current task against the current owner; a match
implies a nested call and we reenter.  If the values do not match then
we block on the lock until it is released.
Signed-off-by: default avatarMike Turquette <mturquette@linaro.org>
Cc: Rajagopal Venkat <rajagopal.venkat@linaro.org>
Cc: David Brown <davidb@codeaurora.org>
Tested-by: default avatarLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
Reviewed-by: default avatarUlf Hansson <ulf.hansson@linaro.org>
      533ddeb1
    • Mike Turquette's avatar
      clk: abstract locking out into helper functions · eab89f69
      Mike Turquette authored 
      Create locking helpers for the global mutex and global spinlock.  The
definitions of these helpers will be expanded upon in the next patch
which introduces reentrancy into the locking scheme.
Signed-off-by: default avatarMike Turquette <mturquette@linaro.org>
Cc: Rajagopal Venkat <rajagopal.venkat@linaro.org>
Cc: David Brown <davidb@codeaurora.org>
Tested-by: default avatarLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
Reviewed-by: default avatarUlf Hansson <ulf.hansson@linaro.org>
      eab89f69
  7. 27 Mar, 2013 2 commits
    • Michal Simek's avatar
      clk: zynq: Add missing zynq clk header · 43c4120c
      Michal Simek authored 
      Include zynq clk header where init function is declared.

It removes this sparse warning:
drivers/clk/clk-zynq.c:373:13: warning: symbol
'xilinx_zynq_clocks_init' was not declared. Should it be static?
Signed-off-by: default avatarMichal Simek <michal.simek@xilinx.com>
Signed-off-by: default avatarMike Turquette <mturquette@linaro.org>
      43c4120c
    • Emilio López's avatar
      clk: sunxi: rename compatible strings · e3276998
      Emilio López authored 
      During the introduction of the Allwinner SoC platforms, sunxi was
initially meant as a generic name for all the variants of the Allwinner
SoC.

It was ok at the time of the support of only the A10 and A13 that
look pretty much the same; but it's beginning to be troublesome with
the future addition of the Allwinner A31 (sun6i) that is quite
different, and would introduce some weird logic, where sunxi would
actually mean in some case sun4i and sun5i but without sun6i...

Moreover, it makes the compatible strings naming scheme not consistent
with other architectures, where usually for this kind of compability, we
just use the oldest SoC name that has this IP, so let's do just this.
Signed-off-by: default avatarEmilio López <emilio@elopez.com.ar>
Signed-off-by: default avatarMike Turquette <mturquette@linaro.org>
      e3276998
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