linux-kernel - Re: [PATCH v3 5/5] clk: samsung: add exynos7870 CLKOUT support

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Message-ID: <31cad1da1a02aaf0935d35e9b56357fcea9320fa.camel@gmail.com>
Date: Fri, 28 Feb 2025 20:07:15 +0100
From: David Virag <virag.david003@...il.com>
To: Krzysztof Kozlowski <krzk@...nel.org>, Kaustabh Chakraborty
	 <kauschluss@...root.org>
Cc: Sylwester Nawrocki <s.nawrocki@...sung.com>, Chanwoo Choi	
 <cw00.choi@...sung.com>, Alim Akhtar <alim.akhtar@...sung.com>, Michael
 Turquette <mturquette@...libre.com>, Stephen Boyd <sboyd@...nel.org>, Rob
 Herring <robh@...nel.org>,  Conor Dooley <conor+dt@...nel.org>, Krzysztof
 Kozlowski <krzk+dt@...nel.org>, linux-kernel@...r.kernel.org, 
	linux-samsung-soc@...r.kernel.org, linux-clk@...r.kernel.org, 
	devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v3 5/5] clk: samsung: add exynos7870 CLKOUT support

On Mon, 2025-02-24 at 20:13 +0100, Krzysztof Kozlowski wrote:
> On 24/02/2025 18:47, Kaustabh Chakraborty wrote:
> > > 
> > > I wonder why do we need to keep growing this list? All devices
> > > are
> > > compatible, aren't they?
> > 
> > Well, there are two variants of compatibility having different mask
> > values.
> > 
> > > Do you use clkout, BTW?
> > 
> > Using the clocks defined by clkout? No. I added it as downstream
> > had it too. And the devices work fine without it. If you want me
> > to remove this patch and send the PMU patch to its respective
> > series I'll do that then (unless you object or suggest something
> > else).
> 
> clkout is a testing tool and I doubt you can use it on a phone -
> finding
> the actual clkout pins to connect the oscilloscope is tricky.

Actually, jackpotlte uses one of the clkout pins (7885 has two) to feed
it's NFC chip with a clock. 

Not sure if any 7870 (or any other Exynos) devices use it for something
similar but here we have at least one example of a non-debug use for
it. I will avoid it on 7885 though until it's actually needed and I can
test the functionality (and when I have the time to work on 7885
again).

Best Regards,
David