linux-kernel - [PATCH] clk: meson: axg: mark fdiv2 and fdiv3 as critical

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Message-Id: <20181108093123.21498-1-jbrunet@baylibre.com>
Date:   Thu,  8 Nov 2018 10:31:23 +0100
From:   Jerome Brunet <jbrunet@...libre.com>
To:     Stephen Boyd <sboyd@...nel.org>,
        Neil Armstrong <narmstrong@...libre.com>,
        Carlo Caione <carlo@...one.org>,
        Kevin Hilman <khilman@...libre.com>
Cc:     Jerome Brunet <jbrunet@...libre.com>,
        Michael Turquette <mturquette@...libre.com>,
        linux-amlogic@...ts.infradead.org, linux-clk@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] clk: meson: axg: mark fdiv2 and fdiv3 as critical

Similar to gxbb and gxl platforms, axg SCPI Cortex-M co-processor
uses the fdiv2 and fdiv3 to, among other things, provide the cpu
clock.

Until clock hand-off mechanism makes its way to CCF and the generic
SCPI claims platform specific clocks, these clocks must be marked as
critical to make sure they are never disabled when needed by the
co-processor.

Fixes: 05f814402d61 ("clk: meson: add fdiv clock gates")
Signed-off-by: Jerome Brunet <jbrunet@...libre.com>
---

Hi Stephen,

If you can put this one in clk-fixes as well, it would be awesome.
It is basically the same thing as the change you took this Tuesday.

Since then, we had reports the same problem with SCPI was happening
on the axg, calling for the same fixup.

Cheers
Jerome

 drivers/clk/meson/axg.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/drivers/clk/meson/axg.c b/drivers/clk/meson/axg.c
index c981159b02c0..792735d7e46e 100644
--- a/drivers/clk/meson/axg.c
+++ b/drivers/clk/meson/axg.c
@@ -325,6 +325,7 @@ static struct clk_regmap axg_fclk_div2 = {
 		.ops = &clk_regmap_gate_ops,
 		.parent_names = (const char *[]){ "fclk_div2_div" },
 		.num_parents = 1,
+		.flags = CLK_IS_CRITICAL,
 	},
 };
 
@@ -349,6 +350,18 @@ static struct clk_regmap axg_fclk_div3 = {
 		.ops = &clk_regmap_gate_ops,
 		.parent_names = (const char *[]){ "fclk_div3_div" },
 		.num_parents = 1,
+		/*
+		 * FIXME:
+		 * This clock, as fdiv2, is used by the SCPI FW and is required
+		 * by the platform to operate correctly.
+		 * Until the following condition are met, we need this clock to
+		 * be marked as critical:
+		 * a) The SCPI generic driver claims and enable all the clocks
+		 *    it needs
+		 * b) CCF has a clock hand-off mechanism to make the sure the
+		 *    clock stays on until the proper driver comes along
+		 */
+		.flags = CLK_IS_CRITICAL,
 	},
 };
 
-- 
2.19.1