linux-kernel - [PATCH v2] clk: clk-gpio: propagate rate change to parent

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Date:   Fri, 8 Nov 2019 09:09:24 +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 v2] clk: clk-gpio: propagate rate change to parent

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

For an external clock source, which is gated or (mux-ed) 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>
---
 drivers/clk/clk-gpio.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/clk/clk-gpio.c b/drivers/clk/clk-gpio.c
index 9d930edd6516..255ed505444c 100644
--- a/drivers/clk/clk-gpio.c
+++ b/drivers/clk/clk-gpio.c
@@ -276,11 +276,12 @@ static int gpio_clk_driver_probe(struct platform_device *pdev)

 	if (is_mux)
 		clk = clk_register_gpio_mux(&pdev->dev, node->name,
-				parent_names, num_parents, gpiod, 0);
+				parent_names, num_parents, gpiod,
+				CLK_SET_RATE_PARENT);
 	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