Hi Andy, On 02/04/2016 10:55 AM, Andy Shevchenko wrote: > Hi! > > Today I observed interesting bug / feature of uart layer in the kernel. > I do have a setup which connects two identical devices by serial line. > I run data transferring in one direction and got data corruption on > receiver side (in uart layer, not the driver). > > Here is the dump from test suite and real data from 8250 registers: > > === 8< === > > Needed 16 reads 0 writes Oh oh, inconsistency at pos 1 (0x1). > > Original sample: > 00000000: 7f 45 4c 46 01 01 01 00 00 00 00 00 00 00 00 00 .ELF............ > 00000010: 02 00 03 00 01 00 00 00 19 8d 04 08 34 00 00 00 ............4... > 00000020: 2c f2 00 00 00 00 00 00 34 00 20 00 04 00 28 00 ,.......4. ...(. > > Received sample: > 00000000: 7f 00 45 00 4c 00 46 00 01 00 01 00 01 00 00 00 ..E.L.F......... > 00000010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ > 00000020: 02 00 00 00 03 00 00 00 01 00 00 00 00 19 8d 04 ................ > loops 1 / 1 > > cts: 0 dsr: 0 rng: 0 dcd: 0 rx: 53434 tx: 0 frame 0 ovr 34201 par: 0 > brk: 0 buf_ovrr: 0 > > === 8< === > > R 356.360109 IIR 0xc4 RDI interrupt > R 356.360114 LSR 0x63 DR + OE > R 356.360119 RX 0x7f > R 356.360124 LSR 0x63 DR + still OE > R 356.360128 RX 0x45 > R 356.360133 LSR 0x63 DR + still OE > R 356.360137 RX 0x4c > R 356.360142 LSR 0x63 DR + still OE > R 356.360147 RX 0x46 > R 356.360151 LSR 0x63 DR + still OE > R 356.360156 RX 0x01 > R 356.360160 LSR 0x63 DR + still OE > R 356.360165 RX 0x01 > R 356.360169 LSR 0x63 > R 356.360174 RX 0x01 > > As we can see the data is corrupted on Linux side. Can we somehow fix > this bug/feature? Not quite sure what you see as the issue. 1) That is a lot of overruns. Is that part of the test or are the overruns a regression? 2) If you mean the NUL bytes for overruns, I could have some functional mode mis-branched in the N_TTY line discipline. What are the termios settings on the rx side? Regards, Peter Hurley -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
