From: t.figa@samsung•com (Tomasz Figa)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH 1/4] clk: samsung: out: Add infrastructure to register CLKOUT
Date: Thu, 15 May 2014 16:07:24 +0200 [thread overview]
Message-ID: <5374CA1C.8000207@samsung.com> (raw)
In-Reply-To: <CAPdUM4N=k-pPxdhPQgVHh0fb+nqkgs7StwM2Pb6C8gcjx6dw-w@mail.gmail.com>
Hi Rahul, Tushar,
On 15.05.2014 15:44, Rahul Sharma wrote:
> Hi Tushar,
>
> Basically you are adding a new clock-type for Clkout. IMO clkout
> is not a special hardware. Existing clock types can be reused to
> support clkout. I see 3 major problem here:
>
> 1) Clkout -> (Mux + Gate). You clubbed mux and gate together, and
> exposing as a single clock which is something like a composite clock.
> IMO this is not a recommended way in CCF.
>
> 2) New Clock Type: Since clkout is just a combination of a simple
> mux and gate which are already supported, it is a unnecessary
> duplication.
>
> 3) Clkout registered along with CMU: which is not correct. Clkout is in PMU
> (Separate physical IP) and should be registered as a independent Clock
> provider which provides 1 mux and 1 gate clock (As if now). It should also be
> well connected with main CMU.
>
> I understand the challenge in using regmap interface for a clock provider. But
> we need to identify a clean solution. IMHO a independent clock provider with
> iomap, is relatively cleaner approach till CCF is not ready with regmap based
> reg access for clock registers.
>
> Experts!! please comment.
It's quite unfortunate that Tushar has duplicated the effort to create a
clkout driver, considering the fact that we did have such driver
internally at SRPOL and it was quite nice and simple.
I will post a cleaned-up version today, that is about 2 times smaller in
terms of lines of added code and provides the same functionality,
without introducing custom clock types. In addition, it models the
clkout properly as a feature of PMU, not CMU (CMU only provides outputs
of particular sub-blocks that are fed into the PMU).
Best regards,
Tomasz
next prev parent reply other threads:[~2014-05-15 14:07 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-09 13:00 [PATCH 0/4] Add framework to support clkout Tushar Behera
2014-05-09 13:00 ` [PATCH 1/4] clk: samsung: out: Add infrastructure to register CLKOUT Tushar Behera
2014-05-10 3:51 ` Pankaj Dubey
2014-05-12 4:46 ` Tushar Behera
2014-05-15 13:44 ` Rahul Sharma
2014-05-15 14:07 ` Tomasz Figa [this message]
2014-05-15 14:14 ` Rahul Sharma
2014-05-19 3:30 ` Tushar Behera
2014-05-19 10:44 ` Tomasz Figa
2014-05-09 13:00 ` [PATCH 2/4] clk: samsung: exynos5420: Add xclkout debug clock Tushar Behera
2014-05-09 13:00 ` [PATCH 3/4] clk: samsung: exynos5250: " Tushar Behera
2014-05-09 13:00 ` [PATCH 4/4] ARM: dts: Add pmu-syscon handle for Exynos5420/Exynos5250 clock Tushar Behera
2014-05-10 3:39 ` [PATCH 0/4] Add framework to support clkout Pankaj Dubey
2014-05-12 4:42 ` Tushar Behera
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