linux-kernel - Re: [PATCH AUTOSEL 5.16 02/52] clk: samsung: exynos850: Register clocks early

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Mon, 17 Jan 2022 18:11:16 +0100
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>
To:     Sasha Levin <sashal@...nel.org>, linux-kernel@...r.kernel.org,
        stable@...r.kernel.org
Cc:     Sam Protsenko <semen.protsenko@...aro.org>,
        Sylwester Nawrocki <s.nawrocki@...sung.com>,
        tomasz.figa@...il.com, cw00.choi@...sung.com,
        mturquette@...libre.com, sboyd@...nel.org, matthias.bgg@...il.com,
        linux-samsung-soc@...r.kernel.org, linux-clk@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org
Subject: Re: [PATCH AUTOSEL 5.16 02/52] clk: samsung: exynos850: Register
 clocks early

On 17/01/2022 17:58, Sasha Levin wrote:
> From: Sam Protsenko <semen.protsenko@...aro.org>
> 
> [ Upstream commit bcda841f9bf2cddcf2f000cba96f2e27f6f2bdbf ]
> 
> Some clocks must be registered before init calls. For example MCT clock
> (from CMU_PERI) is needed for MCT timer driver, which is registered
> with TIMER_OF_DECLARE(). By the time we get to core_initcall() used for
> clk-exynos850 platform driver init, it's already too late. Inability to
> get "mct" clock in MCT driver leads to kernel panic, as functions
> registered with *_OF_DECLARE() can't do deferred calls. MCT timer driver
> can't be fixed either, as it's acting as a clock source and it's
> essential to register it in start_kernel() -> time_init().
> 
> Let's register CMU_PERI clocks early, using CLK_OF_DECLARE(). CMU_TOP
> generates clocks needed for CMU_PERI, but it's already registered early.
> 
> While at it, let's cleanup the code a bit, by extracting everything
> related to CMU initialization and registration to the separate function.
> 
> Similar issue was discussed at [1] and addressed in commit 1f7db7bbf031
> ("clk: renesas: cpg-mssr: Add early clock support"), as well as in
> drivers/clk/mediatek/clk-mt2712.c.
> 
> [1] https://patchwork.kernel.org/project/linux-renesas-soc/patch/20180829132954.64862-2-chris.brandt@renesas.com/
> 
> Signed-off-by: Sam Protsenko <semen.protsenko@...aro.org>
> Signed-off-by: Sylwester Nawrocki <s.nawrocki@...sung.com>
> Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>
> Link: https://lore.kernel.org/r/20211122144206.23134-1-semen.protsenko@linaro.org
> Signed-off-by: Sasha Levin <sashal@...nel.org>
> ---
>  drivers/clk/samsung/clk-exynos850.c | 70 ++++++++++++++++++++---------
>  1 file changed, 49 insertions(+), 21 deletions(-)
> 

I propose to skip this one.

Backporting it to v5.16 does not hurt but also does not bring any
benefits for the upstream kernel users. There is no support for
mentioned Exynos850 in v5.16.

It could have only meaning for some downstream, out-of-tree kernels
which apply Exynos850 support on top of v5.16, but then they can just
take this patch as well.


Best regards,
Krzysztof