clk: at91: usb: fix at91rm9200 round and set rate

at91rm9200_clk_usb_set_rate might fail depending on the requested rate,
because the parent_rate / rate remainder is not necessarily zero.
Moreover, when rounding down the calculated rate we might alter the
divisor calculation and end up with an invalid divisor.

To solve those problems, accept a non zero remainder, and always round
division to the closest result.

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Reported-by: Andreas Henriksson <andreas.henriksson@endian.se>
Tested-by: Andreas Henriksson <andreas.henriksson@endian.se>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Michael Turquette <mturquette@linaro.org>

diff --git a/drivers/clk/at91/clk-usb.c b/drivers/clk/at91/clk-usb.c
index 24b5b020753a9e4a66a5d3db7c8f7ad8bee0b928..5b3b63c07524390f7addb9adeea90a089193cc13 100644 (file)
--- a/drivers/clk/at91/clk-usb.c
+++ b/drivers/clk/at91/clk-usb.c
@@ -253,7 +253,7 @@ static long at91rm9200_clk_usb_round_rate(struct clk_hw *hw, unsigned long rate,
 
                tmp_parent_rate = rate * usb->divisors[i];
                tmp_parent_rate = __clk_round_rate(parent, tmp_parent_rate);
-               tmprate = tmp_parent_rate / usb->divisors[i];
+               tmprate = DIV_ROUND_CLOSEST(tmp_parent_rate, usb->divisors[i]);
                if (tmprate < rate)
                        tmpdiff = rate - tmprate;
                else
@@ -281,10 +281,10 @@ static int at91rm9200_clk_usb_set_rate(struct clk_hw *hw, unsigned long rate,
        struct at91_pmc *pmc = usb->pmc;
        unsigned long div;
 
-       if (!rate || parent_rate % rate)
+       if (!rate)
                return -EINVAL;
 
-       div = parent_rate / rate;
+       div = DIV_ROUND_CLOSEST(parent_rate, rate);
 
        for (i = 0; i < RM9200_USB_DIV_TAB_SIZE; i++) {
                if (usb->divisors[i] == div) {