[PATCH v2] clocksource/drivers/timer-ti-dm: fix regression from errata i940 fix

[Daniel Lezcano]

On 19/02/2022 01:03, Suman Anna wrote:
> Hi Tony,
> 
> On 2/3/22 23:35, Drew Fustini wrote:
>> The existing fix for errata i940 causes a conflict for IPU2 which is
>> using timer 3 and 4. From arch/arm/boot/dts/dra7-ipu-dsp-common.dtsi:
>>
>>    &ipu2 {
>>            mboxes = <&mailbox6 &mbox_ipu2_ipc3x>;
>>            ti,timers = <&timer3>;
>>            ti,watchdog-timers = <&timer4>, <&timer9>;
>>    };
>>
>> The conflict was noticed when booting mainline on the BeagleBoard X15
>> which has a TI AM5728 SoC:
>>
>>    remoteproc remoteproc1: 55020000.ipu is available
>>    remoteproc remoteproc1: powering up 55020000.ipu
>>    remoteproc remoteproc1: Booting fw image dra7-ipu2-fw.xem4
>>    omap-rproc 55020000.ipu: could not get timer platform device
>>    omap-rproc 55020000.ipu: omap_rproc_enable_timers failed: -19
>>    remoteproc remoteproc1: can't start rproc 55020000.ipu: -19
>>
>> This change modifies the errata fix to instead use timer 15 and 16 which
>> resolves the timer conflict.
>>
>> It does not appear to introduce any latency regression. Results from
>> cyclictest with original errata fix using dmtimer 3 and 4:
>>
>>    # cyclictest --mlockall --smp --priority=80 --interval=200 --distance=0
>>    policy: fifo: loadavg: 0.02 0.03 0.05
>>
>>    T: 0 ( 1449) P:80 I:200 C: 800368 Min:   0 Act:   32 Avg:   22 Max:  128
>>    T: 1 ( 1450) P:80 I:200 C: 800301 Min:   0 Act:   12 Avg:   23 Max:   70
>>
>> The results after the change to dmtimer 15 and 16:
>>
>>    # cyclictest --mlockall --smp --priority=80 --interval=200 --distance=0
>>    policy: fifo: loadavg: 0.36 0.19 0.07
>>
>>    T: 0 ( 1711) P:80 I:200 C: 759599 Min:   0 Act:    6 Avg:   22 Max:  108
>>    T: 1 ( 1712) P:80 I:200 C: 759539 Min:   0 Act:   19 Avg:   23 Max:   79
>>
> 
> Gentle reminder, I don't see this in linux-next yet, was kinda expecting this
> would be included in the fixes for 5.17.
> 
> Just want to make sure that the patch did not get lost in your mbox.

Applied, thanks


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