• Heiko Stuebner's avatar
    clk-divider: make sure read-only dividers do not write to their register · f0e92143
    Heiko Stuebner authored
    commit 50359819 upstream.
    
    Commit e6d5e7d9 ("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: e6d5e7d9 ("clk-divider: Fix READ_ONLY when divider > 1")
    Reported-by: default avatarZhang Qing <zhangqing@rock-chips.com>
    Signed-off-by: default avatarHeiko Stuebner <heiko@sntech.de>
    Signed-off-by: default avatarStephen Boyd <sboyd@codeaurora.org>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    f0e92143
clk-divider.c 14 KB