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    SubjectRe: [PATCH 0/3] ARM: OMAP5+: Support Duty Cycle Correction(DCC)
    Date
    Quoting Nishanth Menon (2014-05-16 03:45:57)
    > Hi,
    >
    > This patch series has been carried over in vendor kernel for quiet
    > few years now.
    >
    > Unfortunately, it was very recently re-discovered and upstream kernel
    > is noticed to be broken for OMAP5 1.5GHz - at least we are operating
    > DPLL at frequency higher than what it was intended to be when CPUFreq
    > is enabled. Thankfully, with nominal voltage(we dont use AVS yet in
    > upstream for the mentioned platforms) and margins in trimming, we
    > have so far not crashed - but I strongly suspect this might be some
    > boundary case survival.

    DCC also exists in OMAP4. In some cases customers used it, in other
    cases we just ran the PLL way out of spec and the mpu_clk would divide
    by 2.

    Is this broken for OMAP4 as well?

    Regards,
    Mike

    >
    > Verified on the following impacted platforms using 3.15-rc4 based
    > vendor kernel.
    >
    > Before:
    > OMAP5432: http://slexy.org/view/s20cs0qQFg
    > DRA72x: http://slexy.org/view/s2TXtSa6mH (refused to lock)
    > DRA75x: http://slexy.org/view/s20AW8MU5c
    > After:
    > OMAP5432: http://slexy.org/view/s21iAfWxpu
    > DRA72x: http://slexy.org/view/s2hwsvGLmC (locks properly)
    > DRA75x: http://slexy.org/view/s21ehw8WQn
    >
    > Hopefully, we can get these into some kernel revision in some form.
    >
    > NOTE: Support for 4470(which is the only other platform requiring
    > DCC) is not present in upstream kernel and there are no plans to
    > support that SoC, even if it is added at a later point, support can be
    > extended as needed.
    >
    > Series based on v3.15-rc5 tag.
    > Also available on my tree:
    > https://github.com/nmenon/linux-2.6-playground/
    > branch: push/clock/dcc
    >
    > weblink: https://github.com/nmenon/linux-2.6-playground/commits/push/clock/dcc
    >
    > Verification:
    > 3.15-rc4 based kernel - DRA75x-evm, 72x-evm, OMAP5uevm
    > 3.15-rc5 - OMAP5uEVM(only one supporting 1.5GHz atm)
    >
    > Andrii Tseglytskyi (1):
    > ARM: OMAP5+: dpll: support Duty Cycle Correction(DCC)
    >
    > Nishanth Menon (2):
    > clk: dpll: support OMAP5 MPU DPLL that need special handling for
    > higher frequencies
    > ARM: dts: OMAP5/DRA7: use omap5-mpu-dpll-clock capable of dealing
    > with higher frequencies
    >
    > .../devicetree/bindings/clock/ti/dpll.txt | 1 +
    > arch/arm/boot/dts/dra7xx-clocks.dtsi | 2 +-
    > arch/arm/boot/dts/omap54xx-clocks.dtsi | 2 +-
    > arch/arm/mach-omap2/dpll3xxx.c | 9 +++++++++
    > drivers/clk/ti/dpll.c | 21 ++++++++++++++++++++
    > include/linux/clk/ti.h | 4 ++++
    > 6 files changed, 37 insertions(+), 2 deletions(-)
    >
    > Regards,
    > Nishanth Menon
    > --
    > 1.7.9.5
    >


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