linux-kernel - Re: [PATCHv2] clocksource: dw_apb_timer_of: add error handling if no clock available

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Date:   Sat, 5 Dec 2020 04:55:00 -0600
From:   Dinh Nguyen <dinguyen@...nel.org>
To:     Daniel Lezcano <daniel.lezcano@...aro.org>
Cc:     linux-kernel@...r.kernel.org, tglx@...utronix.de,
        Jisheng.Zhang@...aptics.com, arnd@...db.de
Subject: Re: [PATCHv2] clocksource: dw_apb_timer_of: add error handling if no
 clock available

Hi Daniel,

On 12/5/20 2:50 AM, Daniel Lezcano wrote:
> On 04/12/2020 23:39, Dinh Nguyen wrote:
>>
>>
>> On 12/4/20 2:00 PM, Daniel Lezcano wrote:
>>> On 04/12/2020 16:36, Dinh Nguyen wrote:
>>>> commit ("b0fc70ce1f02 arm64: berlin: Select DW_APB_TIMER_OF") added the
>>>> support for the dw_apb_timer into the arm64 defconfig. However, for some
>>>> platforms like the Intel Stratix10 and Agilex, the clock manager doesn't
>>>> get loaded until after the timer driver get loaded. Thus, the driver
>>>> hits
>>>> the panic "No clock nor clock-frequency property for" because it cannot
>>>> properly get the clock.
>>>>
>>>> This patch adds the error handling needed for the timer driver so that
>>>> the kernel can continue booting instead of just hitting the panic.
>>>>
>>>> Signed-off-by: Dinh Nguyen <dinguyen@...nel.org>
>>>
>>> Did you have time to test the different combinations ?
>>
>> I did test both versions and did not see any difference between the two.
>> On both versions, the kernel was able to continue to boot after trying
>> to probe the timer driver.
> 
> Great, thanks!
> 

I forgot to test this on ARM 32-bit system that actually uses one of 
these timers as a clocksource. The v2 patch would fail. The return of 
PTR_ERR(timer_clk) needs an IS_ERR(timer_clk) check.

I have sent a v3.

Sorry about that.

Dinh