lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:   Fri,  1 May 2020 21:37:01 -0700
From:   Amit Sunil Dhamne <amit.sunil.dhamne@...inx.com>
To:     mturquette@...libre.com, sboyd@...nel.org, michal.simek@...inx.com,
        mark.rutland@....com, linux-clk@...r.kernel.org
Cc:     rajanv@...inx.com, jollys@...inx.com,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Tejas Patel <tejas.patel@...inx.com>,
        Jolly Shah <jolly.shah@...inx.com>,
        Amit Sunil Dhamne <amit.sunil.dhamne@...inx.com>
Subject: [RESEND PATCH v2 2/4] drivers: clk: zynqmp: Fix divider2 calculation

From: Tejas Patel <tejas.patel@...inx.com>

zynqmp_get_divider2_val() calculates, divider value of type DIV2 clock,
considering best possible combination of DIV1 and DIV2.

To find best possible values of DIV1 and DIV2, DIV1's parent rate
should be consider and not DIV2's parent rate since it would rate of
div1 clock. Consider a below topology,

        out_clk->div2_clk->div1_clk->fixed_parent

where out_clk = (fixed_parent/div1_clk) / div2_clk, so parent clock
of div1_clk (i.e. out_clk) should be divided by div1_clk and div2_clk.

Existing code divides parent rate of div2_clk's clock instead of
div1_clk's parent rate, which is wrong.

Fix the same by considering div1's parent clock rate.

Fixes: 4ebd92d2e228 ("clk: zynqmp: Fix divider calculation")
Signed-off-by: Tejas Patel <tejas.patel@...inx.com>
Signed-off-by: Jolly Shah <jolly.shah@...inx.com>
Signed-off-by: Amit Sunil Dhamne <amit.sunil.dhamne@...inx.com>
---
 drivers/clk/zynqmp/divider.c | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/drivers/clk/zynqmp/divider.c b/drivers/clk/zynqmp/divider.c
index 5c41ddb..f7b3545 100644
--- a/drivers/clk/zynqmp/divider.c
+++ b/drivers/clk/zynqmp/divider.c
@@ -111,23 +111,30 @@ static unsigned long zynqmp_clk_divider_recalc_rate(struct clk_hw *hw,

 static void zynqmp_get_divider2_val(struct clk_hw *hw,
                                    unsigned long rate,
-                                   unsigned long parent_rate,
                                    struct zynqmp_clk_divider *divider,
                                    int *bestdiv)
 {
        int div1;
        int div2;
        long error = LONG_MAX;
-       struct clk_hw *parent_hw = clk_hw_get_parent(hw);
-       struct zynqmp_clk_divider *pdivider = to_zynqmp_clk_divider(parent_hw);
+       unsigned long div1_prate;
+       struct clk_hw *div1_parent_hw;
+       struct clk_hw *div2_parent_hw = clk_hw_get_parent(hw);
+       struct zynqmp_clk_divider *pdivider =
+                               to_zynqmp_clk_divider(div2_parent_hw);

        if (!pdivider)
                return;

+       div1_parent_hw = clk_hw_get_parent(div2_parent_hw);
+       if (!div1_parent_hw)
+               return;
+
+       div1_prate = clk_hw_get_rate(div1_parent_hw);
        *bestdiv = 1;
        for (div1 = 1; div1 <= pdivider->max_div;) {
                for (div2 = 1; div2 <= divider->max_div;) {
-                       long new_error = ((parent_rate / div1) / div2) - rate;
+                       long new_error = ((div1_prate / div1) / div2) - rate;

                        if (abs(new_error) < abs(error)) {
                                *bestdiv = div2;
@@ -192,7 +199,7 @@ static long zynqmp_clk_divider_round_rate(struct clk_hw *hw,
         */
        if (div_type == TYPE_DIV2 &&
            (clk_hw_get_flags(hw) & CLK_SET_RATE_PARENT)) {
-               zynqmp_get_divider2_val(hw, rate, *prate, divider, &bestdiv);
+               zynqmp_get_divider2_val(hw, rate, divider, &bestdiv);
        }

        if ((clk_hw_get_flags(hw) & CLK_SET_RATE_PARENT) && divider->is_frac)
--
2.7.4

This email and any attachments are intended for the sole use of the named recipient(s) and contain(s) confidential information that may be proprietary, privileged or copyrighted under applicable law. If you are not the intended recipient, do not read, copy, or forward this email message or any attachments. Delete this email message and any attachments immediately.

Powered by blists - more mailing lists