Date:   Wed, 11 Sep 2019 08:03:48 +0200
From:   "H. Nikolaus Schaller" <hns@...delico.com>
To:     Adam Ford <aford173@...il.com>
Cc:     Tony Lindgren <tony@...mide.com>,
        André Roth <neolynx@...il.com>,
        Linux-OMAP <linux-omap@...r.kernel.org>,
        Discussions about the Letux Kernel 
        <letux-kernel@...nphoenux.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Andreas Kemnade <andreas@...nade.info>,
        Nishanth Menon <nm@...com>
Subject: Re: [Letux-kernel] [RFC PATCH 0/3] Enable 1GHz support on omap36xx


> 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...

BR,
Nikolaus

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