Thread (13 messages) 13 messages, 4 authors, 2020-09-14

Re: [RFT 3/4] ARM: dts: exynos: Move CMU assigned ISP clocks to buses in Exynos3250

From: Marek Szyprowski <m.szyprowski@samsung.com>
Date: 2020-08-31 08:29:19
Also in: dri-devel, linux-devicetree, linux-samsung-soc, lkml

Hi Krzysztof,

On 31.08.2020 10:19, Krzysztof Kozlowski wrote:
On Mon, Aug 31, 2020 at 10:11:02AM +0200, Marek Szyprowski wrote:
quoted
On 29.08.2020 19:25, Krzysztof Kozlowski wrote:
quoted
Commit 52005dece527 ("ARM: dts: Add assigned clock parents to CMU node
for exynos3250") added assigned clocks under Clock Management Unit to
fix hangs when accessing ISP registers.

This is not the place for it as CMU does not have a required "clocks"
property:

    arch/arm/boot/dts/exynos3250-artik5-eval.dt.yaml: clock-controller@10030000: 'clocks' is a dependency of 'assigned-clocks'

Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>

---

Not tested and I wonder whether actually correct. For example, what will
happen if devfreq (exynos-bus) is not built in?

Could someone verify it?
Sorry, but this patch is not correct. Those clocks has noting with
bus-freq. The assigned clocks property should stay where it is. Maybe
one need to fix the schemas for dts verification. Those clocks has to be
set (and so generic clock framework does) according to the assigned
clocks properties once the clock controller is instantiated.

The only alternative would be to add exynos-subcmu variant to properly
link CMU with the ISP power domain, but assuming that there is no Exynos
3250 ISP driver in mainline (and probably never will be), it is safe to
keep those clocks sourced from 24MHz crystal.
Thanks for the clarification.  Another solution to silence the warning
could be to add a "clocks" property for FIN_PLL, although the driver
actually does not take it.
Okay, that would be fine. It would make dts match better the hardware 
and this would even help generic clock framework to always instantiate 
CMU after the oscilator fixed-clock (there have been some hacks there at 
some point for that...)

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland


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