Hallo Lothar, On Tue, Mar 29, 2016 at 01:14:43PM +0200, Lothar Waßmann wrote: > On Wed, 23 Mar 2016 16:36:38 +0100 Uwe Kleine-König wrote: > > 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 > ^^^^^^ > This looks rather fishy. Probably a cut-and-paste problem. I tried this several times with various values, the 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 .%.. > > > > 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. > > > Are you sure the clock is enabled when doing your manual tests? I guess they are. For sure the same thing happens with the driver active and the device open. And the symptoms are the same: If the DCDDELTA irq is enabled and active the machine is stuck until the irq upper layers disable the respective irq. Best regards Uwe -- 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
