linux-kernel - [PATCH v3] clk: clk-gpio: propagate rate change to parent

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 linux-cve-announce 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]

Message-ID: <20191108071718.17985-1-alexandru.ardelean@analog.com>
Date:   Fri, 8 Nov 2019 09:17:18 +0200
From:   Alexandru Ardelean <alexandru.ardelean@...log.com>
To:     <linux-clk@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-renesas-soc@...r.kernel.org>
CC:     <sboyd@...nel.org>, <mturquette@...libre.com>, <jsarha@...com>,
        <ce3a@....de>, <geert+renesas@...der.be>, <horms@...ge.net.au>,
        <magnus.damm@...il.com>, <wsa+renesas@...g-engineering.com>,
        Michael Hennerich <michael.hennerich@...log.com>,
        Alexandru Ardelean <alexandru.ardelean@...log.com>
Subject: [PATCH v3] clk: clk-gpio: propagate rate change to parent

From: Michael Hennerich <michael.hennerich@...log.com>

For an external clock source, which is gated via a GPIO, the
rate change should typically be propagated to the parent clock.

The situation where we are requiring this propagation, is when an
external clock is connected to override an internal clock (which typically
has a fixed rate). The external clock can have a different rate than the
internal one, and may also be variable, thus requiring the rate
propagation.

This rate change wasn't propagated until now, and it's unclear about cases
where this shouldn't be propagated. Thus, it's unclear whether this is
fixing a bug, or extending the current driver behavior. Also, it's unsure
about whether this may break any existing setups; in the case that it does,
a device-tree property may be added to disable this flag.

Signed-off-by: Michael Hennerich <michael.hennerich@...log.com>
Signed-off-by: Alexandru Ardelean <alexandru.ardelean@...log.com>
---

Changelog v2 -> v3:
* limited CLK_SET_RATE_PARENT to both gate clk-gpio drivers; did not pay
  close attention to Stephen's comment when he mentioned to only the gate
  clk-gpio driver

Changelog v1 -> v2:
* added CLK_SET_RATE_PARENT to both gate & mux clk-gpio drivers

 drivers/clk/clk-gpio.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/clk/clk-gpio.c b/drivers/clk/clk-gpio.c
index 9d930edd6516..13304cf5f2a8 100644
--- a/drivers/clk/clk-gpio.c
+++ b/drivers/clk/clk-gpio.c
@@ -280,7 +280,7 @@ static int gpio_clk_driver_probe(struct platform_device *pdev)
 	else
 		clk = clk_register_gpio_gate(&pdev->dev, node->name,
 				parent_names ?  parent_names[0] : NULL, gpiod,
-				0);
+				CLK_SET_RATE_PARENT);
 	if (IS_ERR(clk))
 		return PTR_ERR(clk);

-- 
2.20.1