Messages in this thread Patch in this message |  | | From | Peng Fan <> | Subject | RE: [PATCH V2] clk: imx: gate off peripheral clock slice | Date | Mon, 1 Nov 2021 02:26:49 +0000 |
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> Subject: Re: [PATCH V2] clk: imx: gate off peripheral clock slice > > Hello Peng, Abel, > > On 25.10.21 14:08, Abel Vesa wrote: > > On 21-10-25 20:29:02, Peng Fan (OSS) wrote: > >> 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. > >> > >> Tested boot on i.MX8MM/P-EVK board > > I just noticed this breaks earlycon on an i.MX8MN, I assume because the > earlycon driver will access unclocked registers.
Not able to reproduce your issue.
root@imx8mnevk:~# uname -a Linux imx8mnevk 5.15.0-rc7-next-20211029-00001-gbd989abbb94c-dirty #152 SMP Mon Nov 1 10:48:06 CST 2021 aarch64 aarch64 aarch64 GNU/Linux root@imx8mnevk:~# cat /proc/cmdline earlycon console=ttymxc1,115200 root=/dev/mmcblk2p2 rootwait rw
> > On the i.MX8MN, I also noticed that disabling usb_phy_ref hangs the system, > whether via sysfs or via this patch. Still trying to figure that one out.
root@imx8mnevk:~# cat /sys/kernel/debug/clk/clk_summary | grep usb_phy_ref usb_phy_ref 0 0 0 100000000 0 0 50000 N
I am using i.MX8MN-EVK board.
Regards, Peng.
> > Cheers, > Ahmad > > >> Fixes: d3ff9728134e ("clk: imx: Add imx composite clock") > >> Signed-off-by: Peng Fan <peng.fan@nxp.com> > >> --- > >> > >> V2: > >> Add Fixes tag > >> > >> 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, > >> 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, > >> 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); > >> + } > >> + } > > > > Though I'm usually against special cases like this one. I think the > > clock core needs some generic flag that would read the state from HW > > on probe and/or another generic flag for disabling on probe. > > > > But for now, I'm OK with this: > > > > Reviewed-by: Abel Vesa <abel.vesa@nxp.com> > > > >> } > >> > >> div->lock = &imx_ccm_lock; > >> -- > >> 2.30.0 > >> > > > > > > > -- > 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%7C626714 > cd2773448a4c0608d99afbc80d%7C686ea1d3bc2b4c6fa92cd99c5c301635%7 > C0%7C0%7C637711228448591454%7CUnknown%7CTWFpbGZsb3d8eyJWIjoi > MC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C10 > 00&sdata=235%2BBGnDLUAIorqGKVVt%2BUKlSAf5jT68wq2s5FMDolY% > 3D&reserved=0 | > 31137 Hildesheim, Germany | Phone: > +49-5121-206917-0 | > Amtsgericht Hildesheim, HRA 2686 | Fax: > +49-5121-206917-5555 |
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