[PATCH v3 00/10] clk: implement clock rate protection mechanism
jbrunet at baylibre.com
Mon Jun 12 12:44:28 PDT 2017
This Patchset is related the RFC  and the discussion around
CLK_SET_RATE_GATE available here 
This patchset is based on clk-next.
The goal of this patchset is to provide a way for consumers to inform the
system that they depend on the rate of the clock source and can't tolerate
other consumers changing the rate or causing glitches.
With this series there is 3 use-case:
- the provider is not protected: nothing changes
- the provider is protected by only 1 consumer (and only once), then only
this consumer will be able to alter the rate of the clock, as it is the
only one depending on it.
- If the provider is protected more than once, or by the provider itself,
the rate is basically locked and protected against reparenting.
The last patch provide the same functionnality for providers themself,
fixing CLK_SET_RATE_GATE flag (enforce clock gating along the tree)
qcom, at91 and ux500 are the heaviest users of this flag. If anybody having
one these platform could try this series, it would help build confidence
that the platform relying on CLK_SET_RATE_GATE (even if broken) don't get
Changes since RFC:
- Request rework around core_nolock function
- Add clk_set_rate_protect
- Reword clk_rate_protect and clk_unprotect documentation
- Add few comments to explain the code
- Add 2 last patches to fix users of CLK_SET_RATE_GATE
Changes since v1:
- Add patch 4: Check if the rate would actually change before continuing, a
possibly in clk_set_rate.
Changes since v2: 
- Fix issues reported by Adriana Reus (Thanks !)
- Dropped patch "clk: move CLK_SET_RATE_GATE protection from prepare
to enable". This was broken as the protect count, like the prepare_count
should only be accessed under the prepare_lock.
- No change around bail-out code. Mike wanted to ponder a bit more on it.
- Patch 1 still included, could not find the clk-next-protect Mike was
This was tested with the audio use case mentioned in 
Jerome Brunet (10):
clk: take the prepare lock out of clk_core_set_parent
clk: add clk_core_set_phase_nolock function
clk: rework calls to round and determine rate callbacks
clk: use round rate to bail out early in set_rate
clk: add support for clock protection
clk: add clk_set_rate_protect
clk: rollback set_rate_range changes on failure
clk: cosmetic changes to clk_summary debugfs entry
clk: fix incorrect usage of ENOSYS
clk: fix CLK_SET_RATE_GATE with clock rate protection
drivers/clk/clk.c | 428 ++++++++++++++++++++++++++++++++++++-------
include/linux/clk-provider.h | 1 +
include/linux/clk.h | 43 +++++
3 files changed, 402 insertions(+), 70 deletions(-)
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