Hello, I have a problem with an UART on an i.MX25 based machine. I implemented DCD (and other handshake lines) irq handling[1]. Now a user of this patch noticed that DCD handling (at least) is broken. The problem is that the USR2_DCDDELT bit doesn't clear: root@hostname:~ memtool md 0x43f90080+0x34 43f90080: 00000000 00004021 0000078c 00004002 ....!@.......@.. 43f90090: 00000b41 00002040 00005268 0000002b A...@ ..hR..+... 43f900a0: 00000000 000000bf 00002e62 00000008 ........b....... 43f900b0: 0000251c .%.. root@hostname:~ memtool mw 0x43f90098 0x0x40 root@hostname:~ memtool md 0x43f90080+0x34 43f90080: 00000000 00004021 0000078c 00004002 ....!@.......@.. 43f90090: 00000b41 00002040 00005268 0000002b A...@ ..hR..+... 43f900a0: 00000000 000000bf 00002e62 00000008 ........b....... 43f900b0: 0000251c .%.. In fact even writing 0xffff doesn't change the register, where I would expect that the DCDDELT bit (0x40) disappears. I'm sure there is nothing toggling this line. The net effect is that the irq blocks the machine until it is disabled with [ 51.885987] irq 61: nobody cared (try booting with the "irqpoll" option) . This is on an i.MX25 and I checked the erratas also of the newer i.MX cpus, but I didn't find anything. Did I miss something? Is this a known bug? Do you have a recommendation other than not to set UCR3_DCD? I cannot test the same problem for RI because my hardware doesn't use it, but I wouldn't be surprised if that had the same problem. It would be great to get a statement from you on this topic. Best regards Uwe [1] Message-Id: 1457605569-7828-3-git-send-email-u.kleine-koenig@xxxxxxxxxxxxxx -- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | http://www.pengutronix.de/ | -- 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
