linux-kernel - Re: [RFCv1 5/5] arm64/ARM: configs: Change CONFIG_PWM

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Date:   Fri, 18 Oct 2019 16:13:52 +0200
From:   Neil Armstrong <narmstrong@...libre.com>
To:     Anand Moon <linux.amoon@...il.com>,
        Jerome Brunet <jbrunet@...libre.com>
Cc:     Martin Blumenstingl <martin.blumenstingl@...glemail.com>,
        Kevin Hilman <khilman@...libre.com>,
        devicetree <devicetree@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        linux-amlogic@...ts.infradead.org,
        Linux Kernel <linux-kernel@...r.kernel.org>
Subject: Re: [RFCv1 5/5] arm64/ARM: configs: Change CONFIG_PWM_MESON from m to
 y

On 18/10/2019 16:04, Anand Moon wrote:
> Hi Jerome / Neil / Martin,
> 
> On Wed, 9 Oct 2019 at 17:34, Jerome Brunet <jbrunet@...libre.com> wrote:
>>
>>
>> On Wed 09 Oct 2019 at 10:48, Anand Moon <linux.amoon@...il.com> wrote:
>>>
>>> Kernel command line: console=ttyAML0,115200n8
>>> root=PARTUUID=45d7d61e-01 rw rootwait
>>> earlyprintk=serial,ttyAML0,115200 initcall_debug printk.time=y
>>>
>>> [0] https://pastebin.com/eBgJrSKe
>>>
>>>> you can also try the command line parameter "clk_ignore_unused" (it's
>>>> just a gut feeling: maybe a "critical" clock is being disabled because
>>>> it's not wired up correctly).
>>>>
>>>
>>> It look like some clk issue after I added the *clk_ignore_unused* to
>>> kernel command line
>>> it booted further to login prompt and cpufreq DVFS seem to be loaded.
>>> So I could conclude this is clk issue.below is the boot log
>>>
>>> Kernel command line: console=ttyAML0,115200n8
>>> root=PARTUUID=45d7d61e-01 rw rootwait
>>> earlyprintk=serial,ttyAML0,115200 initcall_debug printk.time=y
>>> clk_ignore_unused
>>>
>>> [1] https://pastebin.com/Nsk0wZQJ
>>>
>>
>> Next step it to try narrow down the clock causing the issue.
>> Remove clk_ignore_unused from the command line and add CLK_INGORE_UNUSED
>> to the flag of some clocks your clock controller (g12a I think) until
>>
>> The peripheral clock gates already have this flag (something we should
>> fix someday) so don't bother looking there.
>>
>> Most likely the source of the pwm is getting disabled between the
>> late_init call and the probe of the PWM module. Since the pwm is already
>> active (w/o a driver), gating the clock source shuts dowm the power to
>> the cores.
>>
>> Looking a the possible inputs in pwm driver, I'd bet on fdiv4.
>>
> 
> I had give this above steps a try but with little success.
> I am still looking into this much close.
> 
> Well I am not the expert in clk or bus configuration.
> but after looking into the datasheet of for clk configuration
> I found some bus are not configured correctly.
> 
> As per Amlogic's kernel S922X (Hardkernel)
> below link share the bus controller.
> 
> [0] https://github.com/hardkernel/linux/blob/odroidn2-4.9.y/arch/arm64/boot/dts/amlogic/mesong12b.dtsi#L295-L315
> 
> looking in to current dts changes it looks bit wrong to me.
> 
> *As per 6.1 Memory Map*
> apb_efuse: bus@...00  --> apb_efuse: bus@...30000
> periphs: bus@...00    --> periphs: bus@...34400
> dmc: bus@...00        --> dmc: bus@...38000
> hiu: bus@...00        --> hiu: bus@...3c0000

If these was wrong, the drivers simply won't work, at all

> 
> Also the order of these is not correct.

The order is correct, actually

> 
> Down the line in the datasheet some of the interrupt GIC bit are not
> mapped correctly for example.
> 
> *As per 6.9.2 Interrupt Control Source*
> 223 SD_EMMC_C
> 222 SD_EMMC_B
> 221 SD_EMMC_A

There is an offset between the doc and the actual GIC_SPI line,
they start the datasheet numbers from the GIC_PPI numbers (+32).

Neil

> 
> and so on.
> Please share your thought if these changes are valid.
> 
> Best Regards
> -Anand
>