In case the initial values of the FOD registers are not configured in the OTP or by the bootloader, it is possible that the FOD registers will contain zeroes. The code in vc5_fod_recalc_rate() immediately feeds the FOD divider value obtained from the FOD registers into the div64_u64() and if the FOD divider value is zero, triggers division by zero exception.
Check if the FOD divider value is zero and return the frequency of the FOD output as 0 Hz if it is so. This prevents the division by zero exception. Signed-off-by: Marek Vasut <[email protected]> Cc: Stephen Boyd <[email protected]> Cc: Alexey Firago <[email protected]> Cc: Michael Turquette <[email protected]> Cc: Laurent Pinchart <[email protected]> Cc: [email protected] Tested-by: Laurent Pinchart <[email protected]> on Salvator-XS with the display LVDS output. --- V2: None V3: None --- drivers/clk/clk-versaclock5.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/clk/clk-versaclock5.c b/drivers/clk/clk-versaclock5.c index ea7d552a2f2b..60bf4afb51bd 100644 --- a/drivers/clk/clk-versaclock5.c +++ b/drivers/clk/clk-versaclock5.c @@ -426,6 +426,10 @@ static unsigned long vc5_fod_recalc_rate(struct clk_hw *hw, div_frc = (od_frc[0] << 22) | (od_frc[1] << 14) | (od_frc[2] << 6) | (od_frc[3] >> 2); + /* Avoid division by zero if the output is not configured. */ + if ((div_int == 0) && (div_frc == 0)) + return 0; + /* The PLL divider has 12 integer bits and 30 fractional bits */ return div64_u64((u64)f_in << 24ULL, ((u64)div_int << 24ULL) + div_frc); } -- 2.11.0
