clk: imx: pll14xx: align pdiv with reference manual

commit 37cfd5e457cbdcd030f378127ff2d62776f641e7 upstream.

The PLL14xx hardware can be found on i.MX8M{M,N,P} SoCs and always come
with a 6-bit pre-divider. Neither the reference manuals nor the
datasheets of these SoCs do mention any restrictions. Furthermore the
current code doesn't respect the restrictions from the comment too.

Therefore drop the restriction and align the max pre-divider (pdiv)
value to 63 to get more accurate frequencies.

Fixes: b09c68dc57c9 ("clk: imx: pll14xx: Support dynamic rates")
Cc: stable@vger.kernel.org
Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>
Reviewed-by: Abel Vesa <abel.vesa@linaro.org>
Reviewed-by: Adam Ford <aford173@gmail.com>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Acked-by: Sascha Hauer <s.hauer@pengutronix.de>
Tested-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Link: https://lore.kernel.org/r/20230807084744.1184791-1-m.felsch@pengutronix.de
Signed-off-by: Abel Vesa <abel.vesa@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/clk/imx/clk-pll14xx.c b/drivers/clk/imx/clk-pll14xx.c
index f3856df9230763af06e4bda142e978148ebfdfdb..416d582a9e8e0025a115d6e25ad477f3a05c87f7 100644 (file)
--- a/drivers/clk/imx/clk-pll14xx.c
+++ b/drivers/clk/imx/clk-pll14xx.c
@@ -135,11 +135,10 @@ static void imx_pll14xx_calc_settings(struct clk_pll14xx *pll, unsigned long rat
        /*
         * Fractional PLL constrains:
         *
-        * a) 6MHz <= prate <= 25MHz
-        * b) 1 <= p <= 63 (1 <= p <= 4 prate = 24MHz)
-        * c) 64 <= m <= 1023
-        * d) 0 <= s <= 6
-        * e) -32768 <= k <= 32767
+        * a) 1 <= p <= 63
+        * b) 64 <= m <= 1023
+        * c) 0 <= s <= 6
+        * d) -32768 <= k <= 32767
         *
         * fvco = (m * 65536 + k) * prate / (p * 65536)
         */
@@ -182,7 +181,7 @@ static void imx_pll14xx_calc_settings(struct clk_pll14xx *pll, unsigned long rat
        }
 
        /* Finally calculate best values */
-       for (pdiv = 1; pdiv <= 7; pdiv++) {
+       for (pdiv = 1; pdiv <= 63; pdiv++) {
                for (sdiv = 0; sdiv <= 6; sdiv++) {
                        /* calc mdiv = round(rate * pdiv * 2^sdiv) / prate) */
                        mdiv = DIV_ROUND_CLOSEST(rate * (pdiv << sdiv), prate);