On 05/24/2014 12:07 AM, Mike Turquette wrote:
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?
Yes, its broken. This series does not address the OMAP4 needs for it,
but can be expanded later by just defining a proper clock type with
OMAP4 specific DCC rate limits etc. for it. We would need properly
functioning DVFS for OMAP4 panda first though I guess... (support for
the TPS regulator.)
-Tero
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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