linux-kernel - [PATCH] clk: meson-gxbb: set fclk_div3 as CLK_IS

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Message-Id: <1539425086-10997-1-git-send-email-christianshewitt@gmail.com>
Date:   Sat, 13 Oct 2018 14:04:46 +0400
From:   Christian Hewitt <christianshewitt@...il.com>
To:     unlisted-recipients:; (no To-header on input)
Cc:     christianshewitt@...il.com,
        Neil Armstrong <narmstrong@...libre.com>,
        Jerome Brunet <jbrunet@...libre.com>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Carlo Caione <carlo@...one.org>,
        Kevin Hilman <khilman@...libre.com>,
        linux-amlogic@...ts.infradead.org, linux-clk@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCH] clk: meson-gxbb: set fclk_div3 as CLK_IS_CRITICAL

On the Khadas VIM2 (GXM) and LePotato (GXL) board there are problems
with reboot; e.g. a ~60 second delay between issuing reboot and the
board power cycling (and in some OS configurations reboot will fail
and require manual power cycling).

Similar to 'commit c987ac6f1f088663b6dad39281071aeb31d450a8 ("clk:
meson-gxbb: set fclk_div2 as CLK_IS_CRITICAL")' the SCPI Cortex-M4
Co-Processor seems to depend on FCLK_DIV3 being operational.

Bisect gives 'commit 05f814402d6174369b3b29832cbb5eb5ed287059 ("clk:
meson: add fdiv clock gates") between 4.16 and 4.16-rc1 as the first
bad commit. This added support for the missing clock gates before the
fixed PLL fixed dividers (FCLK_DIVx) and the clock framework which
disabled all the unused fixed dividers, thus it disabled a critical
clock path for the SCPI Co-Processor.

This change simply sets the FCLK_DIV3 gate as critical to ensure
nothing can disable it.

Signed-off-by: Christian Hewitt <christianshewitt@...il.com>
---
 drivers/clk/meson/gxbb.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/clk/meson/gxbb.c b/drivers/clk/meson/gxbb.c
index 86d3ae5..4c8925d 100644
--- a/drivers/clk/meson/gxbb.c
+++ b/drivers/clk/meson/gxbb.c
@@ -509,6 +509,7 @@ static struct clk_fixed_factor gxbb_fclk_div3_div = {
 		.ops = &clk_fixed_factor_ops,
 		.parent_names = (const char *[]){ "fixed_pll" },
 		.num_parents = 1,
+		.flags = CLK_IS_CRITICAL,
 	},
 };

-- 
2.7.4