Re: [PATCH] clk: ti: clkctrl: Fix failed to enable error with double udelay timeout

Re: [PATCH] clk: ti: clkctrl: Fix failed to enable error with double udelay timeout

[Tero Kristo]

On 10/10/2019 17:05, Tony Lindgren wrote:
> * Keerthy <j-keerthy@ti.com> [191007 00:57]:
>>
>>
>> On 30/09/19 9:10 PM, Tony Lindgren wrote:
>>> Commit 3d8598fb9c5a ("clk: ti: clkctrl: use fallback udelay approach if
>>> timekeeping is suspended") added handling for cases when timekeeping is
>>> suspended. But looks like we can still get occasional "failed to enable"
>>> errors on the PM runtime resume path with udelay() returning faster than
>>> expected.
>>>
>>> With ti-sysc interconnect target module driver this leads into device
>>> failure with PM runtime failing with "failed to enable" clkctrl error.
>>>
>>> Let's fix the issue with a delay of two times the desired delay as in
>>> often done for udelay() to account for the inaccuracy.
>>
>> Tested for DS0 and rtc+ddr modes on am43 and ds0 on am33.
>>
>> Tested-by: Keerthy <j-keerthy@ti.com>
> 
> Thanks for testing. This one should be applied into v5.4-rc series
> please if no more comments.

Queued up for 5.4 fixes, thanks.

-Tero

> 
> Regards,
> 
> Tony
> 
>>> Fixes: 3d8598fb9c5a ("clk: ti: clkctrl: use fallback udelay approach if timekeeping is suspended")
>>> Cc: Keerthy <j-keerthy@ti.com>
>>> Cc: Tero Kristo <t-kristo@ti.com>
>>> Signed-off-by: Tony Lindgren <tony@atomide.com>
>>> ---
>>>    drivers/clk/ti/clkctrl.c | 5 +++--
>>>    1 file changed, 3 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/clk/ti/clkctrl.c b/drivers/clk/ti/clkctrl.c
>>> --- a/drivers/clk/ti/clkctrl.c
>>> +++ b/drivers/clk/ti/clkctrl.c
>>> @@ -100,11 +100,12 @@ static bool _omap4_is_timeout(union omap4_timeout *time, u32 timeout)
>>>    	 * can be from a timer that requires pm_runtime access, which
>>>    	 * will eventually bring us here with timekeeping_suspended,
>>>    	 * during both suspend entry and resume paths. This happens
>>> -	 * at least on am43xx platform.
>>> +	 * at least on am43xx platform. Account for flakeyness
>>> +	 * with udelay() by multiplying the timeout value by 2.
>>>    	 */
>>>    	if (unlikely(_early_timeout || timekeeping_suspended)) {
>>>    		if (time->cycles++ < timeout) {
>>> -			udelay(1);
>>> +			udelay(1 * 2);
>>>    			return false;
>>>    		}
>>>    	} else {
>>>

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Re: [PATCH] clk: ti: clkctrl: Fix failed to enable error with double udelay timeout

[Stephen Boyd]

Quoting Tony Lindgren (2019-09-30 08:40:01)
> Commit 3d8598fb9c5a ("clk: ti: clkctrl: use fallback udelay approach if
> timekeeping is suspended") added handling for cases when timekeeping is
> suspended. But looks like we can still get occasional "failed to enable"
> errors on the PM runtime resume path with udelay() returning faster than
> expected.
> 
> With ti-sysc interconnect target module driver this leads into device
> failure with PM runtime failing with "failed to enable" clkctrl error.
> 
> Let's fix the issue with a delay of two times the desired delay as in
> often done for udelay() to account for the inaccuracy.
> 
> Fixes: 3d8598fb9c5a ("clk: ti: clkctrl: use fallback udelay approach if timekeeping is suspended")
> Cc: Keerthy <j-keerthy@ti.com>
> Cc: Tero Kristo <t-kristo@ti.com>
> Signed-off-by: Tony Lindgren <tony@atomide.com>
> ---

Applied to clk-fixes