Date:   Wed, 11 Sep 2019 08:49:47 +0200
From:   "H. Nikolaus Schaller" <hns@...delico.com>
To:     Adam Ford <aford173@...il.com>
Cc:     Nishanth Menon <nm@...com>,
        Linux-OMAP <linux-omap@...r.kernel.org>,
        Tony Lindgren <tony@...mide.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        André Roth <neolynx@...il.com>,
        Discussions about the Letux Kernel 
        <letux-kernel@...nphoenux.org>,
        Andreas Kemnade <andreas@...nade.info>
Subject: Re: [Letux-kernel] [RFC PATCH 0/3] Enable 1GHz support on omap36xx


> Am 11.09.2019 um 08:03 schrieb H. Nikolaus Schaller <hns@...delico.com>:
> 
> 
>> Am 11.09.2019 um 07:13 schrieb H. Nikolaus Schaller <hns@...delico.com>:
>> 
>> Hi Adam,
>> 
>>> Am 11.09.2019 um 02:41 schrieb Adam Ford <aford173@...il.com>:
>>>>>> 
>> 
>>>>>> The error message looks as if we have to enable multi_regulator.
>> 
>>>>> 
>>>>> That will enable both vdd and vbb regulators from what I can tell in the driver.
>>>>> 
>>>>>> And that may need to rename cpu0-supply to vdd-supply (unless the
>>>>>> names can be configured).
>>>>> 
>>>>> That is consistent with what I found.  vdd-supply = <&vcc>; and
>>>>> vbb-supply = <&abb_mpu_iva>;
>>>>> I put them both under the cpu node.  Unfortunately, when I did that,
>>>>> my board crashed.
>>>>> 
>>>>> I am thinking it has something to do with the abb_mpu_iva driver
>>>>> because until this point, we've always operated at 800MHz or lower
>>>>> which all have the same behavior in abb_mpu_iva.
>>>>> 
>>>>> With the patch you posted for the regulator, without the update to
>>>>> cpufreq,  and with debugging enabled, I received the following in
>>>>> dmesg:
>>>>> 
>>>>> [    1.112518] ti_abb 483072f0.regulator-abb-mpu: Missing
>>>>> 'efuse-address' IO resource
>>>>> [    1.112579] ti_abb 483072f0.regulator-abb-mpu: [0]v=1012500 ABB=0
>>>>> ef=0x0 rbb=0x0 fbb=0x0 vset=0x0
>>>>> [    1.112609] ti_abb 483072f0.regulator-abb-mpu: [1]v=1200000 ABB=0
>>>>> ef=0x0 rbb=0x0 fbb=0x0 vset=0x0
>>>>> [    1.112609] ti_abb 483072f0.regulator-abb-mpu: [2]v=1325000 ABB=0
>>>>> ef=0x0 rbb=0x0 fbb=0x0 vset=0x0
>>>>> [    1.112640] ti_abb 483072f0.regulator-abb-mpu: [3]v=1375000 ABB=1
>>>>> ef=0x0 rbb=0x0 fbb=0x0 vset=0x0
>>>>> [    1.112731] ti_abb 483072f0.regulator-abb-mpu: ti_abb_init_timings:
>>>>> Clk_rate=13000000, sr2_cnt=0x00000032
>>>>> 
>>>> 
>>>> Using an unmodified kernel, I changed the device tree to make the abb
>>>> regulator power the cpu instead of vcc.  After doing so, I was able to
>>>> read the microvolt value, and it matched the processor's desired OPP
>>>> voltage, and the debug code showed the abb regulator was attempting to
>>>> set the various index based on the needed voltage.  I think the abb
>>>> driver is working correctly.
>>>> 
>>>> I think tomorrow, I will re-apply the patches and tweak it again to
>>>> support both vdd and vbb regulators.  If it crashes again, I'll look
>>>> more closely at the logs to see if I can determine why.  I think it's
>>>> pretty close.  I also need to go back and find the SmartReflex stuff
>>>> as well.
>>>> 
>>> Well, I couldn't give it up for the night, so I thought I'd show my data dump
>>> 
>>> [    9.807647] ------------[ cut here ]------------
>>> [    9.812469] WARNING: CPU: 0 PID: 68 at drivers/opp/core.c:630
>>> dev_pm_opp_set_rate+0x3cc/0x480
>>> [    9.821044] Modules linked in: sha256_generic sha256_arm cfg80211
>>> joydev mousedev evdev snd_soc_omap_twl4030(+) leds_gpio led_class
>>> panel_simple pwm_omap_dmtimer gpio_keys pwm_bl cpufreq_dt omap3_isp v
>>> ideobuf2_dma_contig videobuf2_memops videobuf2_v4l2 videobuf2_common
>>> bq27xxx_battery_hdq v4l2_fwnode snd_soc_omap_mcbsp bq27xxx_battery
>>> snd_soc_ti_sdma omap_wdt videodev mc omap_hdq wlcore_sdio wire cn ph
>>> y_twl4030_usb hwmon omap2430 musb_hdrc omap_mailbox twl4030_wdt
>>> watchdog udc_core rtc_twl snd_soc_twl4030 ohci_platform(+)
>>> snd_soc_core snd_pcm_dmaengine ohci_hcd snd_pcm ehci_omap(+)
>>> twl4030_pwrbutton sn
>>> d_timer twl4030_charger snd pwm_twl_led pwm_twl ehci_hcd industrialio
>>> soundcore twl4030_keypad matrix_keymap usbcore at24 tsc2004
>>> tsc200x_core usb_common omap_ssi hsi omapdss omapdss_base drm
>>> drm_panel_or
>>> ientation_quirks cec
>>> [    9.894470] CPU: 0 PID: 68 Comm: kworker/0:2 Not tainted
>>> 5.3.0-rc3-00785-gfdfc7f21c6b7-dirty #5
>>> [    9.903198] Hardware name: Generic OMAP36xx (Flattened Device Tree)
>>> [    9.909515] Workqueue: events dbs_work_handler
>>> [    9.914031] [<c01122d8>] (unwind_backtrace) from [<c010c8b8>]
>>> (show_stack+0x10/0x14)
>>> [    9.921813] [<c010c8b8>] (show_stack) from [<c089e858>]
>>> (dump_stack+0xb4/0xd4)
>>> [    9.929107] [<c089e858>] (dump_stack) from [<c0139eb0>]
>>> (__warn.part.3+0xa8/0xd4)
>>> [    9.936614] [<c0139eb0>] (__warn.part.3) from [<c013a034>]
>>> (warn_slowpath_null+0x40/0x4c)
>>> [    9.944854] [<c013a034>] (warn_slowpath_null) from [<c06d666c>]
>>> (dev_pm_opp_set_rate+0x3cc/0x480)
>>> [    9.953796] [<c06d666c>] (dev_pm_opp_set_rate) from [<bf1790ac>]
>>> (set_target+0x30/0x58 [cpufreq_dt])
>>> [    9.963012] [<bf1790ac>] (set_target [cpufreq_dt]) from
>>> [<c06db05c>] (__cpufreq_driver_target+0x188/0x514)
>>> [    9.972717] [<c06db05c>] (__cpufreq_driver_target) from
>>> [<c06de050>] (od_dbs_update+0x130/0x15c)
>>> [    9.981567] [<c06de050>] (od_dbs_update) from [<c06deb08>]
>>> (dbs_work_handler+0x28/0x58)
>>> [    9.989624] [<c06deb08>] (dbs_work_handler) from [<c0154ab0>]
>>> (process_one_work+0x20c/0x500)
>>> [    9.998107] [<c0154ab0>] (process_one_work) from [<c0155e8c>]
>>> (worker_thread+0x2c/0x5bc)
>>> [   10.006256] [<c0155e8c>] (worker_thread) from [<c015ab88>]
>>> (kthread+0x134/0x148)
>>> [   10.013702] [<c015ab88>] (kthread) from [<c01010e8>]
>>> (ret_from_fork+0x14/0x2c)
>>> [   10.020965] Exception stack(0xde63bfb0 to 0xde63bff8)
>>> [   10.026062] bfa0:                                     00000000
>>> 00000000 00000000 00000000
>>> [   10.034271] bfc0: 00000000 00000000 00000000 00000000 00000000
>>> 00000000 00000000 00000000
>>> [   10.042510] bfe0: 00000000 00000000 00000000 00000000 00000013 00000000
>>> [   10.049224] ---[ end trace cf0e15fa4bd57700 ]---
>>> [   10.053894] cpu cpu0: multiple regulators are not supported
>>> [   10.059509] cpufreq: __target_index: Failed to change cpu frequency: -22
>> 
>> I have the same:
>> 
>> [    4.701354] cpu cpu0: multiple regulators are not supported
>> [    4.707794] cpufreq: __target_index: Failed to change cpu frequency: -22
>> 
>> Comes from within dev_pm_opp_set_rate().
>> 
>> It appears that we also have to define opp_table->set_opp to make use
>> of _set_opp_custom(). And I am not sure which custom-opp-setter we should
>> use. Maybe ti_opp_supply_set_opp() is ok. Or not.
> 
> This appears to be set by dra7.dtsi through loading the
> "ti,omap5-opp-supply" compatible driver:
> 
> https://elixir.bootlin.com/linux/v5.3-rc8/source/arch/arm/boot/dts/dra7.dtsi#L699
> 
> Maybe we can use "ti,omap-opp-supply" here, which does not read
> additional eFuses?
> 
> See also
> 
> https://www.kernel.org/doc/Documentation/devicetree/bindings/opp/ti-omap5-opp-supply.txt
> 
> And, if I understand the code ti_opp_supply_set_opp() correctly, we may not have
> to rename cpu0-suppy to vdd-supply because that driver takes the first
> regulator as vdd and the second as vbb.
> 
> Something like
> 
> opp_supply_mpu_iva: opp_supply {
> 	compatible = "ti,omap-opp-supply";
> 	ti,absolute-max-voltage-uv = <1375000>;
> };
> 
> But that is a quite wild guess...

Well,
seems to boot without complaints and do something reasonable!

[  144.816009] regulator regulator.3: ti_abb_get_voltage_sel
[  144.821685] regulator regulator.3: ti_abb_get_voltage_sel idx=2
[  144.828521] regulator regulator.3: ti_abb_set_voltage_sel: choose sel 1
[  145.133605] regulator regulator.3: ti_abb_get_voltage_sel
[  145.139404] regulator regulator.3: ti_abb_get_voltage_sel idx=1
[  145.146881] regulator regulator.3: ti_abb_set_voltage_sel: choose sel 0
[  145.174163] regulator regulator.3: ti_abb_set_voltage_sel: choose sel 1
[  145.449493] regulator regulator.3: ti_abb_set_voltage_sel: choose sel 0
[  145.485534] regulator regulator.3: ti_abb_set_voltage_sel: choose sel 2

(I have added printk to ti_abb_get_voltage_sel/ti_abb_set_voltage_sel).

I can also see that there are transitions on the voltages (reg.8 is vdd and reg.3 is abb).

root@...ux:~# cat /sys/class/regulator/regulator.8/microvolts 
1012500
root@...ux:~# cat /sys/class/regulator/regulator.8/microvolts 
1325000
root@...ux:~# cat /sys/class/regulator/regulator.8/microvolts 
1200000
root@...ux:~#

root@...ux:~# cat /sys/class/regulator/regulator.3/microvolts
1325000
root@...ux:~# cat /sys/class/regulator/regulator.3/microvolts
1200000
root@...ux:~# cat /sys/class/regulator/regulator.3/microvolts
1200000
root@...ux:~#

What I haven't checked so far is if it toggles the ABB FBB bit.

I have pushed my current work (the last 4 commits) to

http://git.goldelico.com/?p=letux-kernel.git;a=shortlog;h=refs/heads/work-dm3730-1ghz

so that you can inspect/compare/test/check before I tidy up and add
the patches for our OPP-v2 patch set.

BR,
Nikolaus

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