From: Krzysztof Kozlowski <krzk@kernel.org>
To: Sylwester Nawrocki <s.nawrocki@samsung.com>,
Tomasz Figa <tomasz.figa@gmail.com>,
Chanwoo Choi <cw00.choi@samsung.com>,
Michael Turquette <mturquette@baylibre.com>,
Stephen Boyd <sboyd@kernel.org>, Kukjin Kim <kgene@kernel.org>,
linux-samsung-soc@vger.kernel.org, linux-clk@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Subject: Re: [PATCH 2/2] clk: samsung: exynos-clkout: convert to module driver
Date: Wed, 28 Oct 2020 23:07:33 +0100 [thread overview]
Message-ID: <20201028220733.GB271157@kozik-lap> (raw)
In-Reply-To: <20201001165646.32279-3-krzk@kernel.org>
On Thu, Oct 01, 2020 at 06:56:46PM +0200, Krzysztof Kozlowski wrote:
> The Exynos clkout driver depends on board input clock (typically XXTI or
> XUSBXTI), however on Exynos4 boards these clocks were modeled as part of
> SoC clocks (Exynos4 clocks driver). Obviously this is not proper, but
> correcting it would break DT backward compatibility.
>
> Both drivers - clkout and Exynos4 clocks - register the clock providers
> with CLK_OF_DECLARE/OF_DECLARE_1 so their order is fragile (in the
> Makefile clkout is behind Exynos4 clock). It will work only if the
> Exynos4 clock driver comes up before clkout.
>
> A change in DTS adding input clock reference to Exynos4 clocks input
> PLL, see reverted commit eaf2d2f6895d ("ARM: dts: exynos: add input
> clock to CMU in Exynos4412 Odroid"), caused probe reorder: the clkout
> appeared before Exynos4 clock provider. Since clkout depends on Exynos4
> clocks and does not support deferred probe, this did not work and caused
> later failure of usb3503 USB hub probe which needs clkout:
>
> [ 5.007442] usb3503 0-0008: unable to request refclk (-517)
>
> The Exynos clkout driver is not a critical/core clock so there is
> actually no problem in instantiating it later, as a regular module.
> This removes specific probe ordering and adds support for probe
> deferral.
>
> Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
> ---
> drivers/clk/samsung/clk-exynos-clkout.c | 198 +++++++++++++++++-------
> 1 file changed, 141 insertions(+), 57 deletions(-)
Applied (with fixes pointed out by Sylwester).
Best regards,
Krzysztof
prev parent reply other threads:[~2020-10-28 22:07 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-01 16:56 [PATCH 0/2] samsung: exynos: convert clkout to module driver Krzysztof Kozlowski
2020-10-01 16:56 ` [PATCH 1/2] soc: samsung: exynos-pmu: instantiate clkout driver as MFD Krzysztof Kozlowski
2020-10-14 2:44 ` Stephen Boyd
2020-10-23 11:34 ` Sylwester Nawrocki
2020-10-23 11:37 ` Krzysztof Kozlowski
2020-10-28 22:02 ` Krzysztof Kozlowski
2020-10-01 16:56 ` [PATCH 2/2] clk: samsung: exynos-clkout: convert to module driver Krzysztof Kozlowski
2020-10-14 2:43 ` Stephen Boyd
2020-10-14 6:17 ` Krzysztof Kozlowski
2020-10-23 11:42 ` Sylwester Nawrocki
2020-10-28 22:07 ` Krzysztof Kozlowski [this message]
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