Hi Marc, > On 02/29/2016 10:21 AM, Ramesh Shanmugasundaram wrote: > > Added r8a7795 SoC support. > > > > For smoother bit timing calculation, the rounded clock frequency is > used. > > Why this? From my point of view this introduces a clock error. Thanks for the comments. Without the rounded clock, can_calc_bittiming returns different BRP values and reports high sampling error percentage. However, the rounded clock shows no such issues and it works fine for all bitrates. Below is an e.g. from my board for an input clock differs by 2Hz. root@salvator-x:~# can-calc-bit-timing -c 39999998 rcar_can Bit timing parameters for rcar_can with 39.999998 MHz ref clock nominal real Bitrt nom real SampP Bitrate TQ[ns] PrS PhS1 PhS2 SJW BRP Bitrate Error SampP SampP Error CiBCR 1000000 125 2 3 2 1 5 999999 0.0% 75.0% 75.0% 0.0% 0x40040100 800000 125 3 4 2 1 5 799999 0.0% 80.0% 80.0% 0.0% 0x60040100 500000 250 2 3 2 1 10 499999 0.0% 87.5% 75.0% 14.3% 0x40090100 250000 500 2 3 2 1 20 249999 0.0% 87.5% 75.0% 14.3% 0x40130100 125000 1000 2 3 2 1 40 124999 0.0% 87.5% 75.0% 14.3% 0x40270100 100000 1250 2 3 2 1 50 99999 0.0% 87.5% 75.0% 14.3% 0x40310100 50000 2500 2 3 2 1 100 49999 0.0% 87.5% 75.0% 14.3% 0x40630100 20000 6250 2 3 2 1 250 19999 0.0% 87.5% 75.0% 14.3% 0x40f90100 10000 12500 2 3 2 1 500 9999 0.0% 87.5% 75.0% 14.3% 0x41f30100 root@salvator-x:~# can-calc-bit-timing -c 40000000 rcar_can Bit timing parameters for rcar_can with 40.000000 MHz ref clock nominal real Bitrt nom real SampP Bitrate TQ[ns] PrS PhS1 PhS2 SJW BRP Bitrate Error SampP SampP Error CiBCR 1000000 50 7 7 5 1 2 1000000 0.0% 75.0% 75.0% 0.0% 0xd0010400 800000 125 3 4 2 1 5 800000 0.0% 80.0% 80.0% 0.0% 0x60040100 500000 125 6 7 2 1 5 500000 0.0% 87.5% 87.5% 0.0% 0xc0040100 250000 250 6 7 2 1 10 250000 0.0% 87.5% 87.5% 0.0% 0xc0090100 125000 500 6 7 2 1 20 125000 0.0% 87.5% 87.5% 0.0% 0xc0130100 100000 625 6 7 2 1 25 100000 0.0% 87.5% 87.5% 0.0% 0xc0180100 50000 1250 6 7 2 1 50 50000 0.0% 87.5% 87.5% 0.0% 0xc0310100 20000 3125 6 7 2 1 125 20000 0.0% 87.5% 87.5% 0.0% 0xc07c0100 10000 6250 6 7 2 1 250 10000 0.0% 87.5% 87.5% 0.0% 0xc0f90100 Thanks, Ramesh
