• Quanyang Wang's avatar
    clk: zynqmp: pll: add set_pll_mode to check condition in zynqmp_pll_enable · 394cdb69
    Quanyang Wang authored
    If there is a IOCTL_SET_PLL_FRAC_MODE request sent to ATF ever,
    we shouldn't skip invoking PM_CLOCK_ENABLE fn even though this
    pll has been enabled. In ATF implementation, it will only assign
    the mode to the variable (struct pm_pll *)pll->mode when handling
    IOCTL_SET_PLL_FRAC_MODE call. Invoking PM_CLOCK_ENABLE can force
    ATF send request to PWU to set the pll mode to PLL's register.
    
    There is a scenario that happens in enabling VPLL_INT(clk_id:96):
    1) VPLL_INT has been enabled during booting.
    2) A driver calls clk_set_rate and according to the rate, the VPLL_INT
       should be set to FRAC mode. Then zynqmp_pll_set_mode is called
       to pass IOCTL_SET_PLL_FRAC_MODE to ATF. Note that at this point
       ATF just stores the mode to a variable.
    3) This driver calls clk_prepare_enable and zynqmp_pll_enable is
       called to try to enable VPLL_INT pll. Because of 1), the function
       zynqmp_pll_enable just returns without doing anything after checking
       that this pll has been enabled.
    
    In the scenario above, the pll mode of VPLL_INT will never be set
    successfully. So adding set_pll_mode to check condition to fix it.
    
    Fixes: 3fde0e16 ("drivers: clk: Add ZynqMP clock driver")
    Signed-off-by: default avatarQuanyang Wang <quanyang.wang@windriver.com>
    Tested-by: default avatarLaurent Pinchart <laurent.pinchart@ideasonboard.com>
    Link: https://lore.kernel.org/r/20210406153131.601701-1-quanyang.wang@windriver.comSigned-off-by: default avatarStephen Boyd <sboyd@kernel.org>
    394cdb69
pll.c 8.25 KB