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Message-ID: <5613F9AC.3090609@lysator.liu.se> Date: Tue, 6 Oct 2015 18:41:16 +0200 From: Peter Rosin <peda@...ator.liu.se> To: Christian Gmeiner <christian.gmeiner@...il.com> Cc: Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, Wolfram Sang <wsa@...-dreams.de>, "linux-arm-kernel@...ts.infradead.org" <linux-arm-kernel@...ts.infradead.org>, Ludovic Desroches <ludovic.desroches@...el.com>, Cyrille Pitchen <cyrille.pitchen@...el.com> Subject: Re: Regression: at24 eeprom writing On 2015-10-05 08:16, Christian Gmeiner wrote: > Hi Peter. > > Sorry for the late answer - I am currently on my way to Dublin. Maybe > it helps if you enable > I2C_DEBUG_CORE and I2C_DEBUG_BUS. In theory you should see a little > bit better what > happens on the bus. Good suggestion. I did a new run (vanilla 4.2), and this is what I saw on the bus this time: [0.00000] S W50 0x00 "product = 1-776-" P [0.00184] S W50 NACK P [0.00195] S W50 NACK P [0.02027] S W50 0x10 ACK... [0.04035] ...ACK 0x10 "3.0\n" P [0.04100] S W50 NACK P [0.04111] S W50 NACK P [0.06032] S W50 "serial = 380" P [0.06174] S W50 NACK P [0.06185] S W50 NACK P [0.08032] S W50 0x20 ACK... [0.10034] ...ACK 0x20 "000002\n" P [0.10127] S W50 NACK P [0.10138] S W50 NACK P [0.12039] S W50 0x27 " " P [0.12155] S W50 NACK P [0.12166] S W50 NACK P [0.14040] S W50 0x30 " " P [0.14219] S W50 NACK P [0.14230] S W50 NACK P [0.16042] S W50 0x40 " " P ... And this is the corresponding part of the log from the same run (offset ~197.79 s): [ 197.790000] i2c i2c-0: master_xfer[0] W, addr=0x50, len=17 [ 197.790000] i2c i2c-0: at91_xfer: processing 1 messages: [ 197.790000] at91_i2c f0014000.i2c: transfer: write 17 bytes. [ 197.800000] at91_i2c f0014000.i2c: transfer complete [ 197.800000] i2c i2c-0: master_xfer[0] W, addr=0x50, len=5 [ 197.800000] i2c i2c-0: at91_xfer: processing 1 messages: [ 197.800000] at91_i2c f0014000.i2c: transfer: write 5 bytes. [ 197.800000] at91_i2c f0014000.i2c: wrote 0x10, to go 4 [ 197.800000] at91_i2c f0014000.i2c: wrote 0x33, to go 3 [ 197.800000] at91_i2c f0014000.i2c: received nack [ 197.820000] i2c i2c-0: master_xfer[0] W, addr=0x50, len=5 [ 197.820000] i2c i2c-0: at91_xfer: processing 1 messages: [ 197.820000] at91_i2c f0014000.i2c: transfer: write 5 bytes. [ 197.820000] at91_i2c f0014000.i2c: wrote 0x10, to go 4 [ 197.820000] at91_i2c f0014000.i2c: received nack [ 197.840000] i2c i2c-0: master_xfer[0] W, addr=0x50, len=5 [ 197.840000] i2c i2c-0: at91_xfer: processing 1 messages: [ 197.840000] at91_i2c f0014000.i2c: transfer: write 5 bytes. [ 197.840000] at91_i2c f0014000.i2c: wrote 0x10, to go 4 [ 197.840000] at91_i2c f0014000.i2c: wrote 0x33, to go 3 [ 197.840000] at91_i2c f0014000.i2c: wrote 0x2e, to go 2 [ 197.840000] at91_i2c f0014000.i2c: wrote 0x30, to go 1 [ 197.840000] at91_i2c f0014000.i2c: wrote 0xa, to go 0 [ 197.840000] at91_i2c f0014000.i2c: transfer complete [ 197.840000] i2c i2c-0: master_xfer[0] W, addr=0x50, len=13 [ 197.840000] i2c i2c-0: at91_xfer: processing 1 messages: [ 197.840000] at91_i2c f0014000.i2c: transfer: write 13 bytes. [ 197.840000] at91_i2c f0014000.i2c: received nack [ 197.860000] i2c i2c-0: master_xfer[0] W, addr=0x50, len=13 [ 197.860000] i2c i2c-0: at91_xfer: processing 1 messages: [ 197.860000] at91_i2c f0014000.i2c: transfer: write 13 bytes. [ 197.860000] at91_i2c f0014000.i2c: transfer complete [ 197.860000] i2c i2c-0: master_xfer[0] W, addr=0x50, len=8 [ 197.860000] i2c i2c-0: at91_xfer: processing 1 messages: [ 197.860000] at91_i2c f0014000.i2c: transfer: write 8 bytes. [ 197.860000] at91_i2c f0014000.i2c: wrote 0x20, to go 7 [ 197.860000] at91_i2c f0014000.i2c: wrote 0x30, to go 6 [ 197.860000] at91_i2c f0014000.i2c: received nack [ 197.880000] i2c i2c-0: master_xfer[0] W, addr=0x50, len=8 [ 197.880000] i2c i2c-0: at91_xfer: processing 1 messages: [ 197.880000] at91_i2c f0014000.i2c: transfer: write 8 bytes. [ 197.880000] at91_i2c f0014000.i2c: wrote 0x20, to go 7 [ 197.880000] at91_i2c f0014000.i2c: received nack [ 197.900000] i2c i2c-0: master_xfer[0] W, addr=0x50, len=8 [ 197.900000] i2c i2c-0: at91_xfer: processing 1 messages: [ 197.900000] at91_i2c f0014000.i2c: transfer: write 8 bytes. [ 197.900000] at91_i2c f0014000.i2c: wrote 0x20, to go 7 [ 197.900000] at91_i2c f0014000.i2c: wrote 0x30, to go 6 [ 197.900000] at91_i2c f0014000.i2c: wrote 0x30, to go 5 [ 197.900000] at91_i2c f0014000.i2c: wrote 0x30, to go 4 [ 197.900000] at91_i2c f0014000.i2c: wrote 0x30, to go 3 [ 197.900000] at91_i2c f0014000.i2c: wrote 0x30, to go 2 [ 197.900000] at91_i2c f0014000.i2c: wrote 0x32, to go 1 [ 197.900000] at91_i2c f0014000.i2c: wrote 0xa, to go 0 [ 197.900000] at91_i2c f0014000.i2c: transfer complete [ 197.900000] i2c i2c-0: master_xfer[0] W, addr=0x50, len=10 [ 197.900000] i2c i2c-0: at91_xfer: processing 1 messages: [ 197.900000] at91_i2c f0014000.i2c: transfer: write 10 bytes. [ 197.900000] at91_i2c f0014000.i2c: received nack [ 197.920000] i2c i2c-0: master_xfer[0] W, addr=0x50, len=10 [ 197.920000] i2c i2c-0: at91_xfer: processing 1 messages: [ 197.920000] at91_i2c f0014000.i2c: transfer: write 10 bytes. [ 197.920000] at91_i2c f0014000.i2c: transfer complete [ 197.920000] i2c i2c-0: master_xfer[0] W, addr=0x50, len=17 [ 197.920000] i2c i2c-0: at91_xfer: processing 1 messages: [ 197.920000] at91_i2c f0014000.i2c: transfer: write 17 bytes. [ 197.920000] at91_i2c f0014000.i2c: received nack [ 197.940000] i2c i2c-0: master_xfer[0] W, addr=0x50, len=17 [ 197.940000] i2c i2c-0: at91_xfer: processing 1 messages: [ 197.940000] at91_i2c f0014000.i2c: transfer: write 17 bytes. [ 197.940000] at91_i2c f0014000.i2c: transfer complete [ 197.940000] i2c i2c-0: master_xfer[0] W, addr=0x50, len=17 [ 197.940000] i2c i2c-0: at91_xfer: processing 1 messages: [ 197.940000] at91_i2c f0014000.i2c: transfer: write 17 bytes. [ 197.940000] at91_i2c f0014000.i2c: received nack [ 197.960000] i2c i2c-0: master_xfer[0] W, addr=0x50, len=17 [ 197.960000] i2c i2c-0: at91_xfer: processing 1 messages: [ 197.960000] at91_i2c f0014000.i2c: transfer: write 17 bytes. [ 197.960000] at91_i2c f0014000.i2c: transfer complete ... Observations/questions: - The number of NACKs seen on the bus does not match the number of "received nack" messages, every double NACK on the bus only has a single "received nack" message AFAICT. - The bus driver seems to think that the 20ms ACKs are NACKs. Could it be that the eeprom is engaging in clock stretching or something such? - After a 20ms ACK that the bus driver thinks is a NACK, the last command is reissued, but that seems to result in the tail being added to the ongoing command that the bus driver thinks have already terminated with a NACK. Or something? - It seems to work better when I write spaces. Cheers, Peter -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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