linux-kernel - [PATCH 5.8 13/85] clk: samsung: Keep top BPLL mux on Exynos542x enabled

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Message-Id: <20201005142115.370229476@linuxfoundation.org>
Date:   Mon,  5 Oct 2020 17:26:09 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Lukasz Luba <lukasz.luba@....com>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Sylwester Nawrocki <s.nawrocki@...sung.com>
Subject: [PATCH 5.8 13/85] clk: samsung: Keep top BPLL mux on Exynos542x enabled

From: Marek Szyprowski <m.szyprowski@...sung.com>

commit 0212a0483b0a36cc94cfab882b3edbb41fcfe1cd upstream.

BPLL clock must not be disabled because it is needed for proper DRAM
operation. This is normally handled by respective memory devfreq driver,
but when that driver is not yet probed or its probe has been deferred
the clock might get disabled what causes board hang. Fix this by calling
clk_prepare_enable() directly from the clock provider driver.

Cc: stable@...r.kernel.org
Signed-off-by: Marek Szyprowski <m.szyprowski@...sung.com>
Reviewed-by: Lukasz Luba <lukasz.luba@....com>
Tested-by: Lukasz Luba <lukasz.luba@....com>
Acked-by: Krzysztof Kozlowski <krzk@...nel.org>
Link: https://lore.kernel.org/r/20200807133143.22748-1-m.szyprowski@samsung.com
Fixes: 6e7674c3c6df ("memory: Add DMC driver for Exynos5422")
Signed-off-by: Sylwester Nawrocki <s.nawrocki@...sung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/clk/samsung/clk-exynos5420.c |    5 +++++
 1 file changed, 5 insertions(+)

--- a/drivers/clk/samsung/clk-exynos5420.c
+++ b/drivers/clk/samsung/clk-exynos5420.c
@@ -1655,6 +1655,11 @@ static void __init exynos5x_clk_init(str
 	 * main G3D clock enablement status.
 	 */
 	clk_prepare_enable(__clk_lookup("mout_sw_aclk_g3d"));
+	/*
+	 * Keep top BPLL mux enabled permanently to ensure that DRAM operates
+	 * properly.
+	 */
+	clk_prepare_enable(__clk_lookup("mout_bpll"));
 
 	samsung_clk_of_add_provider(np, ctx);
 }