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authorHeiko Stuebner <heiko@sntech.de>2016-01-21 21:53:09 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2016-05-11 11:21:11 +0200
commitf0e92143b8e2e6fa1e854385667427011cfe1059 (patch)
tree3ad99dd3ca9e2a7ee6416a22fdb8851fe0ddd68a /include
parentd65bf4e2407824aecba454c1b0bc7908a5113047 (diff)
clk-divider: make sure read-only dividers do not write to their register
commit 50359819794b4a16ae35051cd80f2dab025f6019 upstream. Commit e6d5e7d90be9 ("clk-divider: Fix READ_ONLY when divider > 1") removed the special ops struct for read-only clocks and instead opted to handle them inside the regular ops. On the rk3368 this results in breakage as aclkm now gets set a value. While it is the same divider value, the A53 core still doesn't like it, which can result in the cpu ending up in a hang. The reason being that "ACLKENMasserts one clock cycle before the rising edge of ACLKM" and the clock should only be touched when STANDBYWFIL2 is asserted. To fix this, reintroduce the read-only ops but do include the round_rate callback. That way no writes that may be unsafe are done to the divider register in any case. The Rockchip use of the clk_divider_ops is adapted to this split again, as is the nxp, lpc18xx-ccu driver that was included since the original commit. On lpc18xx-ccu the divider seems to always be read-only so only uses the new ops now. Fixes: e6d5e7d90be9 ("clk-divider: Fix READ_ONLY when divider > 1") Reported-by: Zhang Qing <zhangqing@rock-chips.com> Signed-off-by: Heiko Stuebner <heiko@sntech.de> Signed-off-by: Stephen Boyd <sboyd@codeaurora.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include')
-rw-r--r--include/linux/clk-provider.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
index c56988ac63f7..7cd0171963ae 100644
--- a/include/linux/clk-provider.h
+++ b/include/linux/clk-provider.h
@@ -384,6 +384,7 @@ struct clk_divider {
#define CLK_DIVIDER_MAX_AT_ZERO BIT(6)
extern const struct clk_ops clk_divider_ops;
+extern const struct clk_ops clk_divider_ro_ops;
unsigned long divider_recalc_rate(struct clk_hw *hw, unsigned long parent_rate,
unsigned int val, const struct clk_div_table *table,