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From:   Chen-Yu Tsai <wens@csie.org>
To:     Maxime Ripard <maxime.ripard@bootlin.com>,
        Michael Turquette <mturquette@baylibre.com>,
        Stephen Boyd <sboyd@kernel.org>
Cc:     Chen-Yu Tsai <wens@csie.org>, linux-clk@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        Philipp Rossak <embed3d@gmail.com>, stable@vger.kernel.org
Subject: [PATCH] clk: sunxi-ng: a31: Fix CLK_OUT_* clock ops
Date:   Sat, 17 Feb 2018 21:05:04 +0800
Message-Id: <20180217130504.8668-1-wens@csie.org>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

When support for the A31/A31s CCU was first added, the clock ops for
the CLK_OUT_* clocks was set to the wrong type. The clocks are MP-type,
but the ops was set for div (M) clocks. This went unnoticed until now.
This was because while they are different clocks, their data structures
aligned in a way that ccu_div_ops would access the second ccu_div_internal
and ccu_mux_internal structures, which were valid, if not incorrect.

Furthermore, the use of these CLK_OUT_* was for feeding a precise 32.768
kHz clock signal to the WiFi chip. This was achievable by using the parent
with the same clock rate and no divider. So the incorrect divider setting
did not affect this usage.

Commit 946797aa3f08 ("clk: sunxi-ng: Support fixed post-dividers on MP
style clocks") added a new field to the ccu_mp structure, which broke
the aforementioned alignment. Now the system crashes as div_ops tries
to look up a nonexistent table.

Reported-by: Philipp Rossak <embed3d@gmail.com>
Fixes: c6e6c96d8fa6 ("clk: sunxi-ng: Add A31/A31s clocks")
Cc: <stable@vger.kernel.org>
Signed-off-by: Chen-Yu Tsai <wens@csie.org>
---

Philipp, can you give this a test and report if this fixes thing?
I don't have any A31/A31s boards online to test this.

---
 drivers/clk/sunxi-ng/ccu-sun6i-a31.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/clk/sunxi-ng/ccu-sun6i-a31.c b/drivers/clk/sunxi-ng/ccu-sun6i-a31.c
index 72b16ed1012b..3b97f60540ad 100644
--- a/drivers/clk/sunxi-ng/ccu-sun6i-a31.c
+++ b/drivers/clk/sunxi-ng/ccu-sun6i-a31.c
@@ -762,7 +762,7 @@ static struct ccu_mp out_a_clk = {
 		.features	= CCU_FEATURE_FIXED_PREDIV,
 		.hw.init	= CLK_HW_INIT_PARENTS("out-a",
 						      clk_out_parents,
-						      &ccu_div_ops,
+						      &ccu_mp_ops,
 						      0),
 	},
 };
@@ -783,7 +783,7 @@ static struct ccu_mp out_b_clk = {
 		.features	= CCU_FEATURE_FIXED_PREDIV,
 		.hw.init	= CLK_HW_INIT_PARENTS("out-b",
 						      clk_out_parents,
-						      &ccu_div_ops,
+						      &ccu_mp_ops,
 						      0),
 	},
 };
@@ -804,7 +804,7 @@ static struct ccu_mp out_c_clk = {
 		.features	= CCU_FEATURE_FIXED_PREDIV,
 		.hw.init	= CLK_HW_INIT_PARENTS("out-c",
 						      clk_out_parents,
-						      &ccu_div_ops,
+						      &ccu_mp_ops,
 						      0),
 	},
 };
-- 
2.16.1