On 21-10-22 15:46:20, Peng Fan wrote:

Hi Ahmad,

quoted

Subject: Re: [PATCH] clk: imx: gate off peripheral clock slice

Hello Peng,

On 22.10.21 15:09, Peng Fan (OSS) wrote:

quoted

From: Peng Fan <peng.fan@nxp.com>

The Peripheral clocks are default enabled when SoC power on, and
bootloader not gate off the clocks when booting Linux Kernel.

So Linux Kernel is not aware the peripheral clocks are enabled and
still take them as disabled because of enable count is zero.

Then Peripheral clock's source without clock gated off could be
changed when have assigned-parents in device tree

However, per i.MX8M* reference mannual, "Peripheral clock slices must
be stopped to change the clock source", so need to gate off the the
peripheral clock when registering the clocks to avoid glitch.

This sounds like a fix that should be backported. If so, could you provide a
Fixes: Tag?

We not see any critical issue without this patch, just to avoid
any potential risk here. So I not add fix tag here.

Abel, do you prefer a fixes tag or leave it as is?

Lets put a fixes tag still. That way, it will be backported and
it will probably save someone (who's maybe using an older kernel) a headache.
Plus, it will get in sooner.

Thanks,
Peng.

quoted

Thanks,
Ahmad

quoted

Tested boot on i.MX8MM/P-EVK board

Signed-off-by: Peng Fan <peng.fan@nxp.com>
---
 drivers/clk/imx/clk-composite-8m.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/clk/imx/clk-composite-8m.c

b/drivers/clk/imx/clk-composite-8m.c
index 2dfd6149e528..ee41fbf90589 100644

--- a/drivers/clk/imx/clk-composite-8m.c
+++ b/drivers/clk/imx/clk-composite-8m.c

@@ -184,6 +184,7 @@ struct clk_hw *__imx8m_clk_hw_composite(const

char *name,

quoted

 	struct clk_mux *mux = NULL;
 	const struct clk_ops *divider_ops;
 	const struct clk_ops *mux_ops;
+	u32 val;

 	mux = kzalloc(sizeof(*mux), GFP_KERNEL);
 	if (!mux)

@@ -216,8 +217,14 @@ struct clk_hw *__imx8m_clk_hw_composite(const

char *name,

quoted

 		div->width = PCG_PREDIV_WIDTH;
 		divider_ops = &imx8m_clk_composite_divider_ops;
 		mux_ops = &clk_mux_ops;
-		if (!(composite_flags & IMX_COMPOSITE_FW_MANAGED))
+		if (!(composite_flags & IMX_COMPOSITE_FW_MANAGED)) {
 			flags |= CLK_SET_PARENT_GATE;
+			if (!(flags & CLK_IS_CRITICAL)) {
+				val = readl(reg);
+				val &= ~BIT(PCG_CGC_SHIFT);
+				writel(val, reg);
+			}
+		}
 	}

 	div->lock = &imx_ccm_lock;

--
Pengutronix e.K.                           |
|
Steuerwalder Str. 21                       |
https://eur01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.p
engutronix.de%2F&data=04%7C01%7Cpeng.fan%40nxp.com%7Cb5b827
20263e43680e9208d995597f48%7C686ea1d3bc2b4c6fa92cd99c5c301635%
7C0%7C0%7C637705033902868076%7CUnknown%7CTWFpbGZsb3d8eyJWIj
oiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1
000&sdata=PolK7YYK66Bbyd6KJgINnvma8JZ6OdDZ8e1cp6rvIww%3D&a
mp;reserved=0  |
31137 Hildesheim, Germany                  | Phone:
+49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:
+49-5121-206917-5555 |

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel