[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <SG2PR06MB1038B0596DFE68AFE1B7E83BC3BA0@SG2PR06MB1038.apcprd06.prod.outlook.com>
Date: Mon, 29 Feb 2016 14:06:21 +0000
From: Ramesh Shanmugasundaram <ramesh.shanmugasundaram@...renesas.com>
To: Marc Kleine-Budde <mkl@...gutronix.de>,
"wg@...ndegger.com" <wg@...ndegger.com>,
"horms@...ge.net.au" <horms@...ge.net.au>,
"magnus.damm@...il.com" <magnus.damm@...il.com>,
"robh+dt@...nel.org" <robh+dt@...nel.org>,
"pawel.moll@....com" <pawel.moll@....com>,
"mark.rutland@....com" <mark.rutland@....com>,
"ijc+devicetree@...lion.org.uk" <ijc+devicetree@...lion.org.uk>,
"galak@...eaurora.org" <galak@...eaurora.org>
CC: "linux-renesas-soc@...r.kernel.org"
<linux-renesas-soc@...r.kernel.org>,
"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
"linux-can@...r.kernel.org" <linux-can@...r.kernel.org>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>,
"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
Chris Paterson <Chris.Paterson2@...esas.com>
Subject: RE: [PATCH 1/2] can: rcar_can: Add r8a7795 support
Hi Marc,
> On 02/29/2016 11:00 AM, Marc Kleine-Budde wrote:
> > I think it's better to fix the algorithm. I'll look into it.
>
> What about:
>
> > ./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 125 6 7 2 1 5 499999 0.0% 87.5% 87.5% 0.0%
> 0xc0040100
> > 250000 250 6 7 2 1 10 249999 0.0% 87.5% 87.5% 0.0%
> 0xc0090100
> > 125000 500 6 7 2 1 20 124999 0.0% 87.5% 87.5% 0.0%
> 0xc0130100
> > 100000 625 6 7 2 1 25 99999 0.0% 87.5% 87.5% 0.0%
> 0xc0180100
> > 50000 1250 6 7 2 1 50 49999 0.0% 87.5% 87.5% 0.0%
> 0xc0310100
> > 20000 3125 6 7 2 1 125 19999 0.0% 87.5% 87.5% 0.0%
> 0xc07c0100
> > 10000 6250 6 7 2 1 250 9999 0.0% 87.5% 87.5% 0.0%
> 0xc0f90100
>
I think, it should be correct. Can I have the patch please(can-utils or kernel)? I'll give it a go.
Manual e.g. shows, for 1Mbps and 40MHz clock, two settings are possible
10Tq -> BRP 4
20Tq -> BRP 2
Condition is TSEG1 > TSEG2 >= SJW & bitrate = clock freq/(brp * number of Tq)
Your e.g. satisfies the condition and hopefully it should be OK.
Thanks,
Ramesh
Powered by blists - more mailing lists