Dne sobota, 24. avgust 2019 ob 15:30:57 CEST je Ondřej Jirman napisal(a):

On Sat, Aug 24, 2019 at 03:16:41PM +0200, Jernej Škrabec wrote:

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Dne sobota, 24. avgust 2019 ob 15:05:44 CEST je Ondřej Jirman napisal(a):

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On Sat, Aug 24, 2019 at 02:51:54PM +0200, Jernej Škrabec wrote:

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Dne sobota, 24. avgust 2019 ob 14:46:54 CEST je Ondřej Jirman 

napisal(a):

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Hi,

On Sat, Aug 24, 2019 at 02:32:32PM +0200, Jernej Škrabec wrote:

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Hi!

Dne torek, 20. avgust 2019 ob 17:19:33 CEST je megous-5qf/QAjKc81hl2p70BpVqQ@public.gmane.orgm

napisal(a):

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From: Ondrej Jirman <megous-5qf/QAjKc83QT0dZR+AlfA@public.gmane.org>

RTC on H6 is mostly the same as on H5 and H3. It has slight
differences
mostly in features that are not yet supported by this driver.

Some differences are already stated in the comments in existing
code.
One other difference is that H6 has extra bit in LOSC_CTRL_REG,
called
EXT_LOSC_EN to enable/disable external low speed crystal
oscillator.

It also has bit EXT_LOSC_STA in LOSC_AUTO_SWT_STA_REG, to check
whether
external low speed oscillator is working correctly.

This patch adds support for enabling LOSC when necessary:

- during reparenting
- when probing the clock

H6 also has capacbility to automatically reparent RTC clock from
external crystal oscillator, to internal RC oscillator, if
external
oscillator fails. This is enabled by default. Disable it during
probe.

Signed-off-by: Ondrej Jirman <megous-5qf/QAjKc83QT0dZR+AlfA@public.gmane.org>
Reviewed-by: Chen-Yu Tsai <redacted>
---

 drivers/rtc/rtc-sun6i.c | 40
 ++++++++++++++++++++++++++++++++++++++--
 1 file changed, 38 insertions(+), 2 deletions(-)

diff --git a/drivers/rtc/rtc-sun6i.c b/drivers/rtc/rtc-sun6i.c
index d50ee023b559..b0c3752bed3f 100644
--- a/drivers/rtc/rtc-sun6i.c
+++ b/drivers/rtc/rtc-sun6i.c

@@ -32,9 +32,11 @@

 /* Control register */
 #define SUN6I_LOSC_CTRL				

0x0000

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 #define SUN6I_LOSC_CTRL_KEY			(0x16aa

<< 16)

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+#define SUN6I_LOSC_CTRL_AUTO_SWT_BYPASS		BIT(15)

User manual says that above field is bit 14.

See the previous discussion, this is from BSP.

I have two versions of BSP (don't ask me which) which have this set as
bit
14 and changing this to 14 actually solves all my problems with LOSC
(no
more issues with setting RTC and HDMI-CEC works now - it uses LOSC as
parent) on Tanix TX6 box.

Interesting. Is LOSC fed externally generated clock, or is it setup as a
crystal oscillator on your board?

I really don't know, but here is DT: http://ix.io/1ThI

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Anyway, see here:

https://megous.com/git/linux/tree/drivers/rtc/rtc-sunxi.h?h=h6-4.9-bsp#n
649
https://megous.com/git/linux/tree/drivers/rtc/rtc-sunxi.c?h=h6-4.9-bsp#n
652

Interesting, 4.9 BSP has additional bit definition, which is not
documented in manual and 3.10 BSP to which I refer.

I was referring to 3.10 BSP, which uses only bit 14. I thought that you
named it differently.

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It would be nice to know what's really happening.

My output is:

[    0.832252] sun6i-rtc 7000000.rtc: registered as rtc0
[    0.832257] sun6i-rtc 7000000.rtc: RTC enabled
[    1.728968] sun6i-rtc 7000000.rtc: setting system clock to
1970-01-01T00:00:07 UTC (7)

With change, I get same output.

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I think, you may have just enabled the auto switch feature, and running
the
clock from low precision RC oscillator with your patch.

True, now I think there is no external crystal, but I'm still not sure how
to confirm that.

Visually?

That would explain why it doesn't work for you. The mainline RTC driver
disables auto-switch feature, and if your board doesn't have a crystal for
LOSC, RTC will not generate a clock for the RTC.

H6's dtsi describes by default a situatiuon with external 32k crystal
oscillator. See ext_osc32k node. That's incorrect for your board if it
doesn't have the crystal. You need to fix this in the DTS for your board
instead of patching the driver.

I see that reparenting is supported, but I'm not sure how to fix that in DT. 
Any suggestion?

The driver has parent clock selection logic in case the LOSC crystal is not
used.

Your patch enables automatic detection of LOSC failure and RTC changes clock
to LOSC automatically, despite what's described in the DTS. That may fix
the issue, but is not the correct solution.

Registers on my board look like this (external 32k osc is used) for
reference:

LOSC_CTRL_REG[7000000]: 8011
	KEY_FIELD                      ???                  (0)
	LOSC_AUTO_SWT_BYPASS           EN                   (1)
	LOSC_AUTO_SWT_EN               DIS                  (0)
	EXT_LOSC_EN                    EN                   (1)
	EXT_LOSC_GSM                   LOW                  (0)
	BATTERY_DIR                    DISCHARGE            (0)
	LOSC_SRC_SEL                   EXT32k               (1)

LOSC_AUTO_SWT_STA_REG[7000004]: 1
	EXT_LOSC_STA                   OK                   (0)
	LOSC_AUTO_SWT_PEND             NOEFF                (0)
	LOSC_SRC_SEL_STA               EXT32K               (1)

In my case LOSC_CTRL_REG has value 0x4010 and LOSC_AUTO_SWT_STA_REG
has value 0x4, so there is issue with external crystal (it's missing) and RTC 
switched to internal one.

BTW, what's wrong with automatic switching? Why is it disabled?

Best regards,
Jernej

regards,
	o.

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The real issue probably is that the mainline driver is missing this:

https://megous.com/git/linux/tree/drivers/rtc/rtc-sunxi.c?h=h6-4.9-bsp#n
650

Not sure what you mean by that. ext vs. int source selection?



Best regards,
Jernej

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regards,

	o.

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