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cpu/kinetis: Refactor LPTMR timer implementation#8814

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kYc0o merged 4 commits intoRIOT-OS:masterfrom
jnohlgard:pr/kinetis-periph-timer-tfc
May 29, 2018
Merged

cpu/kinetis: Refactor LPTMR timer implementation#8814
kYc0o merged 4 commits intoRIOT-OS:masterfrom
jnohlgard:pr/kinetis-periph-timer-tfc

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@jnohlgard jnohlgard commented Mar 22, 2018 •
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Contribution description

Refactor Kinetis LPTMR driver to use freerunning counter mode (TFC flag) and get rid of the RTT subtick counter dependency in the implementation.

Comparison between the bench_periph_timer results before and after reveal that the problem reported in #8532 is fixed, and the new implementation provides results which are close to optimal for a 32768 Hz timer.

Issues/PRs references

Fixes #8532
Uses #8531 for benchmarking
Depends on #8928

Result comparison

Good results with this PR

------------- BEGIN STATISTICS --------------
Limits: mean: [-41, 41], variance: [58, 99]
Target error (actual trigger time - expected trigger time), in reference timer ticks
positive: timer is late, negative: timer is early
=== timer_set running ===
   interval    count       sum       sum_sq    min   max  mean  variance
   1 -    2:   25705    455646      2002373      2    35    17     77
   3 -    4:   25533    457326      1973191      2    35    17     77
   5 -    8:   25412    451046      1970014      2    35    17     77
   9 -   16:   25699    458563      2017198      2    36    17     78
  17 -   32:   25832    457768      2018909      1    35    17     78
  33 -   64:   25758    440454      1978830      1    35    17     76
  65 -  128:   25335    414320      1942196      0    34    16     76
 129 -  256:   25254    367689      1979616     -3    32    14     78
 257 -  512:   25677    285822      2020736     -7    31    11     78
      TOTAL   230205   3788634     18459378     -7    36    16     80
=== timer_set resched ===
   interval    count       sum       sum_sq    min   max  mean  variance
   1 -    2:   25369    484188      2000763      2    38    19     78
   3 -    4:   25188    509764      1958162      4    36    20     77
   5 -    8:   25546    513382      1994162      4    36    20     78
   9 -   16:   25491    515802      1980773      4    36    20     77
  17 -   32:   25565    513309      1976695      4    36    20     77
  33 -   64:   25536    497785      1975338      3    36    19     77
  65 -  128:   25226    469163      1978715      2    35    18     78
 129 -  256:   25580    433869      1984646      0    34    16     77
 257 -  512:   25562    344196      2051719     -5    32    13     80
      TOTAL   229063   4281458     20398742     -5    38    18     89
=== timer_set stopped ===
   interval    count       sum       sum_sq    min   max  mean  variance
   1 -    2:   25358    414569      1978321      0    32    16     78
   3 -    4:   25425    417915      1985722      0    32    16     78
   5 -    8:   25528    419527      1979459      0    32    16     77
   9 -   16:   25654    420564      1991475      0    32    16     77
  17 -   32:   25704    416362      2005219      0    32    16     78
  33 -   64:   25373    399093      1984943     -1    32    15     78
  65 -  128:   25514    380799      2005983     -2    31    14     78
 129 -  256:   25707    340960      2017901     -4    30    13     78
 257 -  512:   25464    248312      2017071     -9    28     9     79
      TOTAL   229727   3458101     17502440     -9    32    15     76
=== timer_set resched, stopped ===
   interval    count       sum       sum_sq    min   max  mean  variance
   1 -    2:   25383    414739      1975450      0    32    16     77
   3 -    4:   25207    414519      1952349      0    33    16     77
   5 -    8:   25480    417808      1971313      0    32    16     77
   9 -   16:   25624    423082      1986321      0    33    16     77
  17 -   32:   25686    414774      1995632      0    33    16     77
  33 -   64:   25432    399469      1976666     -1    32    15     77
  65 -  128:   25601    379594      1986523     -1    31    14     77
 129 -  256:   25608    336491      2015353     -4    30    13     78
 257 -  512:   25649    246195      2060183     -9    28     9     80
      TOTAL   229670   3446671     17474966     -9    33    15     76
=== timer_set_absolute running ===
   interval    count       sum       sum_sq    min   max  mean  variance
   1 -    2:   25776    373865      1991879     -2    36    14     77
   3 -    4:   25642    373980      1988302     -1    36    14     77
   5 -    8:   25357    370226      1974292     -2    36    14     77
   9 -   16:   25407    371825      1992329     -2    36    14     78
  17 -   32:   25362    366265      1979713     -2    37    14     78
  33 -   64:   25119    351246      1967622     -3    35    13     78
  65 -  128:   25569    334769      1990278     -4    35    13     77
 129 -  256:   25669    292687      2005469     -6    33    11     78
 257 -  512:   25236    198456      2032245    -10    31     7     80
      TOTAL   229137   3033319     18002180    -10    37    13     78
=== timer_set_absolute resched ===
   interval    count       sum       sum_sq    min   max  mean  variance
   1 -    2:   25799    424871      2414532     -2    40    16     93
   3 -    4:   25479    447482      2483982     -1    37    17     97
   5 -    8:   25534    449205      2467643     -2    37    17     96
   9 -   16:   25323    446661      2460755     -1    37    17     97
  17 -   32:   25471    440200      2464165     -2    37    17     96
  33 -   64:   25444    426795      2472679     -3    36    16     97
  65 -  128:   25568    410044      2484737     -4    36    16     97
 129 -  256:   25349    362396      2517640     -6    35    14     99
 257 -  512:   25559    278883      2547384    -10    32    10     99
      TOTAL   229526   3686537     21698975    -10    40    16     94
=== timer_set_absolute stopped ===
   interval    count       sum       sum_sq    min   max  mean  variance
   1 -    2:   25394    415090      1992582      0    32    16     78
   3 -    4:   25510    422025      1982785      0    33    16     77
   5 -    8:   25503    417777      1987370      0    32    16     77
   9 -   16:   25561    420641      1994500      0    33    16     78
  17 -   32:   25464    415338      1999564      0    32    16     78
  33 -   64:   25421    400033      1972944     -1    32    15     77
  65 -  128:   25365    379725      1983130     -1    31    14     78
 129 -  256:   25430    336270      1976137     -4    30    13     77
 257 -  512:   25603    247256      2058653     -9    28     9     80
      TOTAL   229251   3454155     17502735     -9    33    15     76
=== timer_set_absolute resched, stopped ===
   interval    count       sum       sum_sq    min   max  mean  variance
   1 -    2:   25389    413249      1967576      0    32    16     77
   3 -    4:   25448    419741      2000263      1    33    16     78
   5 -    8:   25537    417992      1988075      0    33    16     77
   9 -   16:   25345    416417      1998092      0    33    16     78
  17 -   32:   25264    410541      1982664      0    32    16     78
  33 -   64:   25554    402257      1993152     -1    32    15     78
  65 -  128:   25597    379344      2036834     -2    32    14     79
 129 -  256:   25714    338831      2036091     -4    30    13     79
 257 -  512:   25532    247781      2057582     -9    28     9     80
      TOTAL   229380   3446153     17594577     -9    33    15     76
=== timer_read statistics ===
Limits: mean: [-10, 10], variance: [0, 16]
timer_read error (TUT time elapsed - expected TUT interval), in timer under test ticks
positive: timer target handling is slow, negative: timer_read is dropping ticks
function              count       sum       sum_sq    min   max  mean  variance
 timer_set           917489     55527        55527      0     1     0      0
  running            229922     24323        24323      0     1     0      0
  resched            228769     31204        31204      0     1     0      0
  stopped            229430         0            0      0     0     0      0
  resched, stopped   229368         0            0      0     0     0      0

 timer_set_absolute  916098     11371        11371      0     1     0      0
  running            228833       174          174      0     1     0      0
  resched            229218     11197        11197      0     1     0      0
  stopped            228979         0            0      0     0     0      0
  resched, stopped   229068         0            0      0     0     0      0
-------------- END STATISTICS ---------------

Bad results from current master

------------- BEGIN STATISTICS --------------
Limits: mean: [-41, 41], variance: [58, 99]
Target error (actual trigger time - expected trigger time), in reference timer ticks
positive: timer is late, negative: timer is early
=== timer_set running ===
   interval    count       sum       sum_sq    min   max  mean  variance
   1 -    2:  151759   8169157     12000186     38    70    53     79  <=== SIC!
   3 -    4:  152055   8188904     11862848     38    70    53     78  <=== SIC!
   5 -    8:  152649   8220089     11964135     38    70    53     78  <=== SIC!
   9 -   16:  152496   8206005     11959285     38    70    53     78  <=== SIC!
  17 -   32:  152474   8190871     11969389     37    70    53     78  <=== SIC!
  33 -   64:  152804   8122016     11896317     37    70    53     77  <=== SIC!
  65 -  128:  152317   7964069     11850482     35    69    52     77  <=== SIC!
 129 -  256:  151744   7682948     11946216     33    68    50     78  <=== SIC!
 257 -  512:  151983   7160562     12116871     28    66    47     79  <=== SIC!
      TOTAL  1370281  71904621    105494065     28    70    52     76  <=== SIC!
=== timer_set resched ===
   interval    count       sum       sum_sq    min   max  mean  variance
   1 -    2:  152263   8206204     12010296     38    70    53     78  <=== SIC!
   3 -    4:  152116   8204391     11931688     38    70    53     78  <=== SIC!
   5 -    8:  152067   8198164     11950671     38    70    53     78  <=== SIC!
   9 -   16:  151560   8167391     11919235     38    70    53     78  <=== SIC!
  17 -   32:  152329   8185912     11909493     37    70    53     78  <=== SIC!
  33 -   64:  151503   8062216     11803110     37    70    53     77  <=== SIC!
  65 -  128:  152167   7970259     11895465     36    69    52     78  <=== SIC!
 129 -  256:  152349   7724101     11986967     33    68    50     78  <=== SIC!
 257 -  512:  152399   7191203     12110072     29    65    47     79  <=== SIC!
      TOTAL  1368753  71909841    105137058     29    70    52     76  <=== SIC!
=== timer_set stopped ===
   interval    count       sum       sum_sq    min   max  mean  variance
   1 -    2:  152436   7912342     12041099     36    68    51     78  <=== SIC!
   3 -    4:  151847   7889039     11893236     36    68    51     78  <=== SIC!
   5 -    8:  152534   7913327     11961832     36    68    51     78  <=== SIC!
   9 -   16:  152352   7908221     11996378     36    68    51     78  <=== SIC!
  17 -   32:  152812   7905451     11944996     35    68    51     78  <=== SIC!
  33 -   64:  152378   7807559     11859982     35    68    51     77  <=== SIC!
  65 -  128:  151639   7642262     11814410     33    67    50     77  <=== SIC!
 129 -  256:  152308   7414758     11989057     31    66    48     78  <=== SIC!
 257 -  512:  152385   6884889     12119216     26    64    45     79  <=== SIC!
      TOTAL  1370691  69277848    105702184     26    68    50     77  <=== SIC!
=== timer_set resched, stopped ===
   interval    count       sum       sum_sq    min   max  mean  variance
   1 -    2:  152208   7904077     12032672     36    68    51     79  <=== SIC!
   3 -    4:  151731   7879622     11898309     36    68    51     78  <=== SIC!
   5 -    8:  152203   7891337     11922765     36    68    51     78  <=== SIC!
   9 -   16:  152467   7911684     11929837     36    68    51     78  <=== SIC!
  17 -   32:  152308   7877985     11948695     35    68    51     78  <=== SIC!
  33 -   64:  152108   7796425     11837918     34    68    51     77  <=== SIC!
  65 -  128:  152676   7691983     11944369     33    67    50     78  <=== SIC!
 129 -  256:  152726   7436216     12081218     31    66    48     79  <=== SIC!
 257 -  512:  152747   6903408     12155173     26    64    45     79  <=== SIC!
      TOTAL  1371174  69292737    105622614     26    68    50     77  <=== SIC!
=== timer_set_absolute running ===
   interval    count       sum       sum_sq    min   max  mean  variance
   1 -    2:  152169 100035262  13265840288     38 769948   657  87178  <=== SIC!
   3 -    4:  152310 104565512  16674414583     38 770314   686 109477  <=== SIC!
   5 -    8:  152079 100886958  14712273714     38 770159   663  96741  <=== SIC!
   9 -   16:  151633  96223372  18396187268     38 771686   634 121321  <=== SIC!
  17 -   32:  152117 104125759  17832726202     37 769975   684 117231  <=== SIC!
  33 -   64:  152298  97972418  13799844569     37 764547   643  90611  <=== SIC!
  65 -  128:  152301 103208853  13581175382     36 767945   677  89173  <=== SIC!
 129 -  256:  152145  99984338  15878683026     33 770257   657 104366  <=== SIC!
 257 -  512:  152115 103898360  20273313407     29 770751   683 133277  <=== SIC!
      TOTAL  1369167 910900832 144757151884     29 771686   665 105726  <=== SIC!
=== timer_set_absolute resched ===
   interval    count       sum       sum_sq    min   max  mean  variance
   1 -    2:  152217  82324291  13339518497     38  1071   540  87635  <=== SIC!
   3 -    4:  152199  82254909  13301794832     38  1071   540  87397  <=== SIC!
   5 -    8:  152023  82085454  13264873203     38  1071   539  87256  <=== SIC!
   9 -   16:  152156  82236539  13265351119     38  1071   540  87183  <=== SIC!
  17 -   32:  152639  82606815  13267666812     38  1071   541  86922  <=== SIC!
  33 -   64:  151883  81836155  13268661551     37  1070   538  87361  <=== SIC!
  65 -  128:  152114  82151495  13228100922     36  1070   540  86962  <=== SIC!
 129 -  256:  152363  81806042  13278055359     34  1069   536  87148  <=== SIC!
 257 -  512:  152360  81235185  13303811951     29  1066   533  87318  <=== SIC!
      TOTAL  1369954 738536885 119197349719     29  1071   539  87008  <=== SIC!
=== timer_set_absolute stopped ===
   interval    count       sum       sum_sq    min   max  mean  variance
   1 -    2:  151970   7886761     11976801     36    68    51     78  <=== SIC!
   3 -    4:  152623   7927814     11957032     36    68    51     78  <=== SIC!
   5 -    8:  152094   7893198     11954578     36    68    51     78  <=== SIC!
   9 -   16:  152332   7901961     11912402     36    68    51     78  <=== SIC!
  17 -   32:  152049   7872382     11920405     35    68    51     78  <=== SIC!
  33 -   64:  152091   7793251     11879647     35    68    51     78  <=== SIC!
  65 -  128:  151448   7632631     11788810     33    67    50     77  <=== SIC!
 129 -  256:  151484   7372482     11974362     31    66    48     79  <=== SIC!
 257 -  512:  152537   6894721     12136568     27    64    45     79  <=== SIC!
      TOTAL  1368628  69175201    105557403     27    68    50     77  <=== SIC!
=== timer_set_absolute resched, stopped ===
   interval    count       sum       sum_sq    min   max  mean  variance
   1 -    2:  151667   7869652     11991800     36    68    51     79  <=== SIC!
   3 -    4:  152199   7904472     11890810     36    68    51     78  <=== SIC!
   5 -    8:  151810   7875692     11913674     36    68    51     78  <=== SIC!
   9 -   16:  152234   7900578     11901225     36    68    51     78  <=== SIC!
  17 -   32:  152066   7867827     11935234     35    68    51     78  <=== SIC!
  33 -   64:  152339   7802074     11834613     35    68    51     77  <=== SIC!
  65 -  128:  152770   7707041     11946908     33    67    50     78  <=== SIC!
 129 -  256:  152918   7446933     12037469     31    66    48     78  <=== SIC!
 257 -  512:  152815   6904741     12163831     27    63    45     79  <=== SIC!
      TOTAL  1370818  69279010    105418288     27    68    50     76  <=== SIC!
=== timer_read statistics ===
Limits: mean: [-10, 10], variance: [0, 16]
timer_read error (TUT time elapsed - expected TUT interval), in timer under test ticks
positive: timer target handling is slow, negative: timer_read is dropping ticks
function              count       sum       sum_sq    min   max  mean  variance
 timer_set          5472033 102022565   2050417904      1    69    18    374  <=== SIC!
  running           1368442   2984851       247967      2     3     2      0
  resched           1366940   3052688       362365      1     4     2      0
  stopped           1368087  47995591    257083445      1    69    35    187  <=== SIC!
  resched, stopped  1368564  47989435    257579309      1    69    35    188  <=== SIC!

 timer_set_absolute 5469149 149465780  76733027671      1 25302    27  14030  <=== SIC!
  running           1366875  28677763  75747486848      2 25302    20  55416  <=== SIC!
  resched           1367833  24874644    128667739      1    35    18     94  <=== SIC!
  stopped           1366172  47919701    256908110      1    69    35    188  <=== SIC!
  resched, stopped  1368269  47993672    257274127      1    69    35    188  <=== SIC!
-------------- END STATISTICS ---------------

@jnohlgard jnohlgard added Type: bug The issue reports a bug / The PR fixes a bug (including spelling errors) Type: enhancement The issue suggests enhanceable parts / The PR enhances parts of the codebase / documentation Platform: ARM Platform: This PR/issue effects ARM-based platforms CI: ready for build If set, CI server will compile all applications for all available boards for the labeled PR Area: timers Area: timer subsystems labels Mar 22, 2018
@jnohlgard jnohlgard added this to the Release 2018.04 milestone Mar 22, 2018
@jnohlgard jnohlgard requested a review from smlng March 22, 2018 07:46
@jnohlgard jnohlgard added the CI: needs squashing Commits in this PR need to be squashed; If set, CI systems will mark this PR as unmergable label Mar 22, 2018
@jnohlgard jnohlgard force-pushed the pr/kinetis-periph-timer-tfc branch from d1d5167 to 752bb57 Compare March 22, 2018 07:48
@jnohlgard jnohlgard removed the CI: needs squashing Commits in this PR need to be squashed; If set, CI systems will mark this PR as unmergable label Mar 22, 2018
@jnohlgard jnohlgard requested a review from kYc0o March 22, 2018 10:05
@jnohlgard jnohlgard mentioned this pull request Mar 22, 2018
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@jnohlgard jnohlgard force-pushed the pr/kinetis-periph-timer-tfc branch 3 times, most recently from 8ca4176 to b1b6f7a Compare March 29, 2018 19:28
@jnohlgard jnohlgard force-pushed the pr/kinetis-periph-timer-tfc branch 2 times, most recently from 543292e to c644b7e Compare April 11, 2018 18:27
@jnohlgard jnohlgard mentioned this pull request Apr 11, 2018
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@jnohlgard jnohlgard force-pushed the pr/kinetis-periph-timer-tfc branch from c644b7e to df6e1bf Compare April 12, 2018 06:11
@jnohlgard jnohlgard changed the title cpu/kinetis: Improve periph timer implementation cpu/kinetis: Refactor LPTMR timer implementation Apr 12, 2018
@jnohlgard jnohlgard force-pushed the pr/kinetis-periph-timer-tfc branch 2 times, most recently from 47a5135 to fa0667e Compare April 18, 2018 09:32
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jnohlgard commented Apr 18, 2018

Rebased after #8928 was merged

@jnohlgard jnohlgard force-pushed the pr/kinetis-periph-timer-tfc branch from fa0667e to 57f2482 Compare April 25, 2018 06:38
@jnohlgard jnohlgard force-pushed the pr/kinetis-periph-timer-tfc branch from 57f2482 to df0e8cd Compare May 21, 2018 14:20
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smlng approved these changes May 22, 2018
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Changes look good to me, ACK.

However, I don't have one of the three boards available for testing, but I tested with PhyNode (pba-d-01-kw2x) to ensure it nothing is broken with the standard timers either: it isn't 😄

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smlng commented May 22, 2018

please squash

cpu/kinetis: Refactor LPTMR driver implementation
9e10cd4 
Uses timer freerunning counter mode (TFC) and updating an internal
reference point instead of relying on RTT for reference time. The
target accuracy has been greatly improved for all test cases in
bench_periph_timer
@jnohlgard jnohlgard force-pushed the pr/kinetis-periph-timer-tfc branch from df0e8cd to dc68900 Compare May 22, 2018 14:45
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kYc0o commented May 29, 2018

I think this one is ready to go!

@kYc0o kYc0o merged commit 6e484f7 into RIOT-OS:master May 29, 2018
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kYc0o commented May 29, 2018

BTW, can the k64f be also updated in a follow-up?

@jnohlgard jnohlgard mentioned this pull request Jun 1, 2018
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@jnohlgard jnohlgard deleted the pr/kinetis-periph-timer-tfc branch June 8, 2018 20:58
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Area: timers Area: timer subsystems CI: ready for build If set, CI server will compile all applications for all available boards for the labeled PR Platform: ARM Platform: This PR/issue effects ARM-based platforms Type: bug The issue reports a bug / The PR fixes a bug (including spelling errors) Type: enhancement The issue suggests enhanceable parts / The PR enhances parts of the codebase / documentation

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kinetis: timer_set_absolute randomly misses its target

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