[PATCH] clk: imx7d: do not set the parent of IMX7D_ENET_AXI_ROOT_SRC

Booting the kernel on a imx7s-warp leads to several warnings like these:

[    0.000000] ------------[ cut here ]------------
[    0.000000] WARNING: CPU: 0 PID: 0 at kernel/locking/lockdep.c:3536 lock_release+0x2f8/0x330
[    0.000000] releasing a pinned lock

[    0.000000] ------------[ cut here ]------------
[    0.000000] WARNING: CPU: 0 PID: 0 at kernel/locking/lockdep.c:2722 trace_hardirqs_on_caller+0x1ac/0x1f4
[    0.000000] DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled))

[    0.000000] ---[ end trace cb88537fdc8fa201 ]---
[    0.000000] bad: scheduling from the idle thread!
[    0.000000] CPU: 0 PID: 0 Comm: swapper/0 Tainted: G        W       4.7.0-rc7-next-20160715 #404

[    0.000000] ------------[ cut here ]------------
[    0.000000] WARNING: CPU: 0 PID: 0 at kernel/time/sched_clock.c:179 sched_clock_register+0x44/0x1f8
[    0.000000] Modules linked in:

[    0.000591] ------------[ cut here ]------------
[    0.000610] WARNING: CPU: 0 PID: 0 at kernel/time/sched_clock.c:179 sched_clock_register+0x44/0x1f8

[    0.002084] ------------[ cut here ]------------
[    0.002104] WARNING: CPU: 0 PID: 0 at init/main.c:576 start_kernel+0x258/0x3b0
[    0.002114] Interrupts were enabled early


This fix is along the same lines as 5e33ebff7edd ("clk: imx7d: do not
set parent of ethernet time/ref clocks") and the explanation from that
commit is:

"The reason for the warning is that setting the parent enables the ENET
 PLL since we are using CLK_OPS_PARENT_ENABLE. Enabling the ENET PLL can
 cause clk_pllv3_wait_lock to sleep. See also:
 commit fc8726a2c021 ("clk: core: support clocks which requires parents
 enable (part 2)")."

imx7s-warp does not even use the FEC interface, so we should not really
configure the parent of IMX7D_ENET_AXI_ROOT_SRC in the common MX7 clock
driver code.

The dts file should use the assigned-clocks/assigned-clock-parents method,
so simply remove the configuration of IMX7D_ENET_AXI_ROOT_SRC parent.

Signed-off-by: Fabio Estevam <redacted>
---
 drivers/clk/imx/clk-imx7d.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/drivers/clk/imx/clk-imx7d.c b/drivers/clk/imx/clk-imx7d.c
index 6ed4f8f..9257972 100644
--- a/drivers/clk/imx/clk-imx7d.c
+++ b/drivers/clk/imx/clk-imx7d.c

@@ -860,8 +860,6 @@ static void __init imx7d_clocks_init(struct device_node *ccm_node)
 	/* use old gpt clk setting, gpt1 root clk must be twice as gpt counter freq */
 	clk_set_parent(clks[IMX7D_GPT1_ROOT_SRC], clks[IMX7D_OSC_24M_CLK]);
 
-	clk_set_parent(clks[IMX7D_ENET_AXI_ROOT_SRC], clks[IMX7D_PLL_ENET_MAIN_250M_CLK]);
-
 	/* set uart module clock's parent clock source that must be great then 80MHz */
 	clk_set_parent(clks[IMX7D_UART1_ROOT_SRC], clks[IMX7D_OSC_24M_CLK]);
 

-- 
1.9.1

Hi Mike,

On Fri, Jul 15, 2016 at 10:53 AM, Fabio Estevam [off-list ref] wrote:

Booting the kernel on a imx7s-warp leads to several warnings like these:

[    0.000000] ------------[ cut here ]------------
[    0.000000] WARNING: CPU: 0 PID: 0 at kernel/locking/lockdep.c:3536 lock_release+0x2f8/0x330
[    0.000000] releasing a pinned lock

[    0.000000] ------------[ cut here ]------------
[    0.000000] WARNING: CPU: 0 PID: 0 at kernel/locking/lockdep.c:2722 trace_hardirqs_on_caller+0x1ac/0x1f4
[    0.000000] DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled))

[    0.000000] ---[ end trace cb88537fdc8fa201 ]---
[    0.000000] bad: scheduling from the idle thread!
[    0.000000] CPU: 0 PID: 0 Comm: swapper/0 Tainted: G        W       4.7.0-rc7-next-20160715 #404

[    0.000000] ------------[ cut here ]------------
[    0.000000] WARNING: CPU: 0 PID: 0 at kernel/time/sched_clock.c:179 sched_clock_register+0x44/0x1f8
[    0.000000] Modules linked in:

[    0.000591] ------------[ cut here ]------------
[    0.000610] WARNING: CPU: 0 PID: 0 at kernel/time/sched_clock.c:179 sched_clock_register+0x44/0x1f8

[    0.002084] ------------[ cut here ]------------
[    0.002104] WARNING: CPU: 0 PID: 0 at init/main.c:576 start_kernel+0x258/0x3b0
[    0.002114] Interrupts were enabled early


This fix is along the same lines as 5e33ebff7edd ("clk: imx7d: do not
set parent of ethernet time/ref clocks") and the explanation from that
commit is:

"The reason for the warning is that setting the parent enables the ENET
 PLL since we are using CLK_OPS_PARENT_ENABLE. Enabling the ENET PLL can
 cause clk_pllv3_wait_lock to sleep. See also:
 commit fc8726a2c021 ("clk: core: support clocks which requires parents
 enable (part 2)")."

imx7s-warp does not even use the FEC interface, so we should not really
configure the parent of IMX7D_ENET_AXI_ROOT_SRC in the common MX7 clock
driver code.

The dts file should use the assigned-clocks/assigned-clock-parents method,
so simply remove the configuration of IMX7D_ENET_AXI_ROOT_SRC parent.

Signed-off-by: Fabio Estevam <redacted>

Do you think this one could be applied to 4.8-rc?

Thanks

On 08/10, Fabio Estevam wrote:

Hi Mike,

On Fri, Jul 15, 2016 at 10:53 AM, Fabio Estevam [off-list ref] wrote:

quoted

Booting the kernel on a imx7s-warp leads to several warnings like these:

[    0.000000] ------------[ cut here ]------------
[    0.000000] WARNING: CPU: 0 PID: 0 at kernel/locking/lockdep.c:3536 lock_release+0x2f8/0x330
[    0.000000] releasing a pinned lock

[    0.000000] ------------[ cut here ]------------
[    0.000000] WARNING: CPU: 0 PID: 0 at kernel/locking/lockdep.c:2722 trace_hardirqs_on_caller+0x1ac/0x1f4
[    0.000000] DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled))

[    0.000000] ---[ end trace cb88537fdc8fa201 ]---
[    0.000000] bad: scheduling from the idle thread!
[    0.000000] CPU: 0 PID: 0 Comm: swapper/0 Tainted: G        W       4.7.0-rc7-next-20160715 #404

[    0.000000] ------------[ cut here ]------------
[    0.000000] WARNING: CPU: 0 PID: 0 at kernel/time/sched_clock.c:179 sched_clock_register+0x44/0x1f8
[    0.000000] Modules linked in:

[    0.000591] ------------[ cut here ]------------
[    0.000610] WARNING: CPU: 0 PID: 0 at kernel/time/sched_clock.c:179 sched_clock_register+0x44/0x1f8

[    0.002084] ------------[ cut here ]------------
[    0.002104] WARNING: CPU: 0 PID: 0 at init/main.c:576 start_kernel+0x258/0x3b0
[    0.002114] Interrupts were enabled early


This fix is along the same lines as 5e33ebff7edd ("clk: imx7d: do not
set parent of ethernet time/ref clocks") and the explanation from that
commit is:

"The reason for the warning is that setting the parent enables the ENET
 PLL since we are using CLK_OPS_PARENT_ENABLE. Enabling the ENET PLL can
 cause clk_pllv3_wait_lock to sleep. See also:
 commit fc8726a2c021 ("clk: core: support clocks which requires parents
 enable (part 2)")."

imx7s-warp does not even use the FEC interface, so we should not really
configure the parent of IMX7D_ENET_AXI_ROOT_SRC in the common MX7 clock
driver code.

The dts file should use the assigned-clocks/assigned-clock-parents method,
so simply remove the configuration of IMX7D_ENET_AXI_ROOT_SRC parent.

Signed-off-by: Fabio Estevam <redacted>

Do you think this one could be applied to 4.8-rc?

Is there a "Fixes:" tag that can be applied here? Does this
depend on some sort of DTS changes to add assigned clocks and
parents?

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project

Hi Stephen,

On Thu, Aug 11, 2016 at 7:28 PM, Stephen Boyd [off-list ref] wrote:

Is there a "Fixes:" tag that can be applied here? Does this

This parent assignment exists since the mx7d clk driver was introduced
in commit 8f6d8094b21 ("ARM: imx: add imx7d clk tree support").

depend on some sort of DTS changes to add assigned clocks and
parents?

All the mx7 dts users assign the ENET clocks in their dts files.

As imx7s-warp is the only affected board and it will be only available
in 4.9, I think it is OK to apply this one into clk-next if you are
happt with it.

Thanks,

Fabio Estevam

Hi,

On 2016-08-11 16:53, Fabio Estevam wrote:

Hi Stephen,

On Thu, Aug 11, 2016 at 7:28 PM, Stephen Boyd [off-list ref] wrote:

quoted

Is there a "Fixes:" tag that can be applied here? Does this

This parent assignment exists since the mx7d clk driver was introduced
in commit 8f6d8094b21 ("ARM: imx: add imx7d clk tree support").

quoted

depend on some sort of DTS changes to add assigned clocks and
parents?

All the mx7 dts users assign the ENET clocks in their dts files.

I don't think so, at least not that root clock.

Otherwise grep -e IMX7D_PLL_ENET_MAIN_250M_CLK arch/arm/boot/dts/imx7*
should return something...

I guess in practice it is not a problem because the boot loader
configures the clock selection already. Still, I think we should also
fix our device trees and select the root clock there...

--
Stefan

Hi Stefan,

On Thu, Aug 11, 2016 at 8:57 PM, Stefan Agner [off-list ref] wrote:

I don't think so, at least not that root clock.

Otherwise grep -e IMX7D_PLL_ENET_MAIN_250M_CLK arch/arm/boot/dts/imx7*
should return something...

Yes, you are right. The enet root clock parent assignment is missing in dts.

Other enet clocks are assigned.

I guess in practice it is not a problem because the boot loader
configures the clock selection already. Still, I think we should also
fix our device trees and select the root clock there...

Yes, I didn't see any error on mx7d-sdb when I tested this patch, but
to be on the safe side I will update all the mx7 fec users to assign
enet root clk in the dts.

Thanks

On 08/11, Fabio Estevam wrote:

Hi Stefan,

On Thu, Aug 11, 2016 at 8:57 PM, Stefan Agner [off-list ref] wrote:

quoted

I don't think so, at least not that root clock.

Otherwise grep -e IMX7D_PLL_ENET_MAIN_250M_CLK arch/arm/boot/dts/imx7*
should return something...

Yes, you are right. The enet root clock parent assignment is missing in dts.

Other enet clocks are assigned.

quoted

I guess in practice it is not a problem because the boot loader
configures the clock selection already. Still, I think we should also
fix our device trees and select the root clock there...

Yes, I didn't see any error on mx7d-sdb when I tested this patch, but
to be on the safe side I will update all the mx7 fec users to assign
enet root clk in the dts.

Ok it sounds like this isn't urgent for fixes. I'll go ahead and
queue it up for v4.9

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project

On Thu, Aug 11, 2016 at 10:45 PM, Stephen Boyd [off-list ref] wrote:

Ok it sounds like this isn't urgent for fixes. I'll go ahead and
queue it up for v4.9

Thanks, Stephen.

On 07/15, Fabio Estevam wrote:

Booting the kernel on a imx7s-warp leads to several warnings like these:

[    0.000000] ------------[ cut here ]------------

Applied to clk-next

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project