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[73.183.52.120]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-5033a4de38esm129309391cf.27.2026.02.03.07.15.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 03 Feb 2026 07:15:42 -0800 (PST) Date: Tue, 3 Feb 2026 10:15:41 -0500 From: Brian Masney To: Stephen Boyd Cc: Michael Turquette , linux-kernel@vger.kernel.org, linux-clk@vger.kernel.org, patches@lists.linux.dev, Alexander Stein , Mark Brown , Nicolas Frattaroli , AngeloGioacchino Del Regno , Chen-Yu Tsai Subject: Re: [PATCH] Revert "clk: Respect CLK_OPS_PARENT_ENABLE during recalc" Message-ID: References: <20260203002439.1223213-1-sboyd@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260203002439.1223213-1-sboyd@kernel.org> User-Agent: Mutt/2.2.14 (2025-02-20) On Mon, Feb 02, 2026 at 04:24:38PM -0800, Stephen Boyd wrote: > This reverts commit 669917676e93fca5ea3c66fc9539830312bec58e. > It's been shown to cause problems on i.MX and STM32 platforms > where the board doesn't boot. In one case, a clk with > CLK_IS_CRITICAL and CLK_OPS_PARENT_ENABLE is being registered > causing the parent to be enabled, the rate recalculated, and then > the parent is disabled causing the critical clk being registered > to stop clocking. > > A fix for that would be to calculate the rate of the clk after > enabling the critical clk itself, but that wouldn't fix another > problem where a clk with CLK_OPS_PARENT_ENABLE is registered > before the parent is registered. In this case the hardware access > in the clk_ops::recalc_rate() function would fail if the parent > is disabled. > > There are even more problems exposed by this patch because it > introduces logic that disables clks earlier in system boot than > has existed previously. Historically we've not disabled clks > until late init (clk_disable_unused) under the assumption that > clks have been registered enough to have a consistent view of the > clk tree. The clk_disable_unused logic doesn't work very well > though, leading to quite a few devices booting with > clk_ignore_unused on the kernel command line. > > Long story short, disabling clks during clk registration is full > of pitfalls. Revert this commit until a proper solution can be > found. > > Reported-by: Alexander Stein > Closes: https://lore.kernel.org/r/6239343.lOV4Wx5bFT@steina-w > Reported-by: Mark Brown > Closes: https://lore.kernel.org/r/036da7ce-6487-4a6e-9b15-97c6d3bcdcec@sirena.org.uk > Cc: Nicolas Frattaroli > Cc: Brian Masney > Cc: AngeloGioacchino Del Regno > Cc: Chen-Yu Tsai > Signed-off-by: Stephen Boyd Reviewed-by: Brian Masney