On 2022-09-14 02:00, Maciej W. Rozycki wrote:
On Tue, 13 Sep 2022, Anders Blomdell wrote:
Seems like CPR/CPR2 does not affect baudrate, so maybe EFR bit 4 (enhance
mode) is not set?
Thanks for assessing the problem. I've thought already it could be
misconfiguration.
If CPR is stuck at 8 (1.0 scaling), it all makes sense, these corresponds to
what the oscilloscope gives:
2400 -> tcr: 9, cpr: 18, quot: 1286
62500000/9/(8*.125)/1286 -> 5400
4800 -> tcr: 7, cpr: 23, quot: 647
2500000/7/(8*.125)/647 -> 13799
9600 -> tcr: 9, cpr: 9, quot: 643
62500000/9/(8*.125)/643 -> 10800.
19200 -> tcr: 8, cpr: 31, quot: 105
62500000/7/(8*.125)/105 -> 85034
38400 -> 62500000/14/(8*.125)/30 -> 148809
Agreed.
As the first debug aid could you please enable DEBUG_AUTOCONF at the top
of drivers/tty/serial/8250/8250_port.c and paste the relevant piece of
8250 initialisation recorded in the kernel log? This will confirm (or
contradict) correct operation of the port configuration sequence.
Modifications done:
diff --git a/drivers/tty/serial/8250/8250.h b/drivers/tty/serial/8250/8250.h
index c89cb881d9b0..f25e824d626e 100644
--- a/drivers/tty/serial/8250/8250.h
+++ b/drivers/tty/serial/8250/8250.h
@@ -115,11 +115,17 @@ struct serial8250_config {
static inline int serial_in(struct uart_8250_port *up, int offset)
{
- return up->port.serial_in(&up->port, offset);
+ int result;
+ result = up->port.serial_in(&up->port, offset);
+ printk(KERN_INFO "serial_in(%px, 0x%02x) -> 0x%02x\n",
+ up, offset, result);
+ return result;
}
static inline void serial_out(struct uart_8250_port *up, int offset, int value)
{
+ printk(KERN_INFO "serial_out(%px, 0x%02x, 0x%02x)\n",
+ up, offset, value);
up->port.serial_out(&up->port, offset, value);
}
diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index 2b86c55ed374..b5c1b1faff34 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -44,7 +44,7 @@
/*
* Debugging.
*/
-#if 0
+#if 1
#define DEBUG_AUTOCONF(fmt...) printk(fmt)
#else
#define DEBUG_AUTOCONF(fmt...) do { } while (0)
Captured data:
[ 3.830006] Serial: 8250/16550 driver, 32 ports, IRQ sharing enabled
[ 3.830141] ttyS0: autoconf (0x03f8, 0x0000000000000000):
[ 3.830146] serial_in(ffffffffb6b97520, 0x01) -> 0xff
[ 3.830271] serial_out(ffffffffb6b97520, 0x01, 0x00)
[ 3.830338] serial_in(ffffffffb6b97520, 0x01) -> 0xff
[ 3.830400] serial_out(ffffffffb6b97520, 0x01, 0x0f)
[ 3.830468] serial_in(ffffffffb6b97520, 0x01) -> 0xff
[ 3.830530] serial_out(ffffffffb6b97520, 0x01, 0xff)
[ 3.830594] IER test failed (0f, 0f)
[ 3.830595] iir=255
[ 3.830656] type=unknown
[ 3.830888] ttyS1: autoconf (0x02f8, 0x0000000000000000):
[ 3.830892] serial_in(ffffffffb6b97800, 0x01) -> 0xff
[ 3.831016] serial_out(ffffffffb6b97800, 0x01, 0x00)
[ 3.831080] serial_in(ffffffffb6b97800, 0x01) -> 0xff
[ 3.831141] serial_out(ffffffffb6b97800, 0x01, 0x0f)
[ 3.831208] serial_in(ffffffffb6b97800, 0x01) -> 0xff
[ 3.831269] serial_out(ffffffffb6b97800, 0x01, 0xff)
[ 3.831332] IER test failed (0f, 0f)
[ 3.831333] iir=255
[ 3.831393] type=unknown
[ 3.831595] ttyS2: autoconf (0x03e8, 0x0000000000000000):
[ 3.831598] serial_in(ffffffffb6b97ae0, 0x01) -> 0xff
[ 3.831720] serial_out(ffffffffb6b97ae0, 0x01, 0x00)
[ 3.831783] serial_in(ffffffffb6b97ae0, 0x01) -> 0xff
[ 3.831844] serial_out(ffffffffb6b97ae0, 0x01, 0x0f)
[ 3.831907] serial_in(ffffffffb6b97ae0, 0x01) -> 0xff
[ 3.831969] serial_out(ffffffffb6b97ae0, 0x01, 0xff)
[ 3.832040] IER test failed (0f, 0f)
[ 3.832041] iir=255
[ 3.832101] type=unknown
[ 3.832305] ttyS3: autoconf (0x02e8, 0x0000000000000000):
[ 3.832309] serial_in(ffffffffb6b97dc0, 0x01) -> 0xff
[ 3.832431] serial_out(ffffffffb6b97dc0, 0x01, 0x00)
[ 3.832497] serial_in(ffffffffb6b97dc0, 0x01) -> 0xff
[ 3.832562] serial_out(ffffffffb6b97dc0, 0x01, 0x0f)
[ 3.832627] serial_in(ffffffffb6b97dc0, 0x01) -> 0xff
[ 3.832688] serial_out(ffffffffb6b97dc0, 0x01, 0xff)
[ 3.832760] IER test failed (0f, 0f)
[ 3.832761] iir=255
[ 3.832820] type=unknown
[ 3.835202] ttyS4: autoconf (0x0000, 0x(____ptrval____)):
[ 3.835207] serial_in(ffffffffb6b980a0, 0x01) -> 0x00
[ 3.836170] serial_out(ffffffffb6b980a0, 0x01, 0x00)
[ 3.836170] serial_in(ffffffffb6b980a0, 0x01) -> 0x00
[ 3.836170] serial_out(ffffffffb6b980a0, 0x01, 0x0f)
[ 3.836170] serial_in(ffffffffb6b980a0, 0x01) -> 0x0f
[ 3.836170] serial_out(ffffffffb6b980a0, 0x01, 0x00)
[ 3.836170] serial_in(ffffffffb6b980a0, 0x04) -> 0x00
[ 3.836170] serial_in(ffffffffb6b980a0, 0x03) -> 0x00
[ 3.836170] serial_out(ffffffffb6b980a0, 0x03, 0xbf)
[ 3.836170] serial_out(ffffffffb6b980a0, 0x02, 0x00)
[ 3.836170] serial_out(ffffffffb6b980a0, 0x03, 0x00)
[ 3.836170] serial_out(ffffffffb6b980a0, 0x02, 0x01)
[ 3.836170] serial_in(ffffffffb6b980a0, 0x02) -> 0xc1
[ 3.836170] serial_out(ffffffffb6b980a0, 0x03, 0x00)
[ 3.836170] serial_out(ffffffffb6b980a0, 0x04, 0x00)
[ 3.836170] serial_out(ffffffffb6b980a0, 0x02, 0x01)
[ 3.836170] serial_out(ffffffffb6b980a0, 0x02, 0x07)
[ 3.836170] serial_out(ffffffffb6b980a0, 0x02, 0x00)
[ 3.836170] serial_in(ffffffffb6b980a0, 0x00) -> 0x78
[ 3.836170] serial_out(ffffffffb6b980a0, 0x01, 0x00)
[ 3.837488] iir=193
[ 3.837490] type=16550A
[ 3.837606] 0000:07:00.0: ttyS4 at MMIO 0xe3601000 (irq = 17, base_baud = 15625000) is a 16550A
[ 3.837685] serial_out(ffffffffb6b980a0, 0x04, 0x80)
[ 3.837914] ttyS5: autoconf (0x0000, 0x(____ptrval____)):
[ 3.837918] serial_in(ffffffffb6b98380, 0x01) -> 0x00
[ 3.838041] serial_out(ffffffffb6b98380, 0x01, 0x00)
[ 3.838104] serial_in(ffffffffb6b98380, 0x01) -> 0x00
[ 3.838165] serial_out(ffffffffb6b98380, 0x01, 0x0f)
[ 3.838229] serial_in(ffffffffb6b98380, 0x01) -> 0x0f
[ 3.838290] serial_out(ffffffffb6b98380, 0x01, 0x00)
[ 3.838353] serial_in(ffffffffb6b98380, 0x04) -> 0x00
[ 3.838417] serial_in(ffffffffb6b98380, 0x03) -> 0x00
[ 3.838479] serial_out(ffffffffb6b98380, 0x03, 0xbf)
[ 3.838541] serial_out(ffffffffb6b98380, 0x02, 0x00)
[ 3.838602] serial_out(ffffffffb6b98380, 0x03, 0x00)
[ 3.838667] serial_out(ffffffffb6b98380, 0x02, 0x01)
[ 3.838731] serial_in(ffffffffb6b98380, 0x02) -> 0xc1
[ 3.838791] serial_out(ffffffffb6b98380, 0x03, 0x00)
[ 3.838853] serial_out(ffffffffb6b98380, 0x04, 0x00)
[ 3.838891] serial_out(ffffffffb6b98380, 0x02, 0x01)
[ 3.838891] serial_out(ffffffffb6b98380, 0x02, 0x07)
[ 3.838891] serial_out(ffffffffb6b98380, 0x02, 0x00)
[ 3.838891] serial_in(ffffffffb6b98380, 0x00) -> 0x1d
[ 3.838891] serial_out(ffffffffb6b98380, 0x01, 0x00)
[ 3.839232] iir=193
[ 3.839233] type=16550A
[ 3.839347] 0000:07:00.0: ttyS5 at MMIO 0xe3601200 (irq = 17, base_baud = 15625000) is a 16550A
[ 3.839424] serial_out(ffffffffb6b98380, 0x04, 0x80)
Running this small test program:
#!/usr/bin/python3
import serial
p2 = serial.Serial('/dev/ttyS4', 19200)
p2.write(b'\x55')
Gives:
[ 132.325041] serial_out(ffffffffb6b980a0, 0x02, 0x01)
[ 132.325055] serial_out(ffffffffb6b980a0, 0x02, 0x07)
[ 132.325060] serial_out(ffffffffb6b980a0, 0x02, 0x00)
[ 132.325077] serial_in(ffffffffb6b980a0, 0x05) -> 0x60
[ 132.325105] serial_out(ffffffffb6b980a0, 0x04, 0x88)
[ 132.325119] serial_in(ffffffffb6b980a0, 0x05) -> 0x60
[ 132.325134] serial_in(ffffffffb6b980a0, 0x06) -> 0xb0
[ 132.325140] serial_out(ffffffffb6b980a0, 0x07, 0x02)
[ 132.325144] serial_out(ffffffffb6b980a0, 0x05, 0x09)
[ 132.325148] serial_out(ffffffffb6b980a0, 0x07, 0x01)
[ 132.325151] serial_out(ffffffffb6b980a0, 0x05, 0x09)
[ 132.325155] serial_out(ffffffffb6b980a0, 0x07, 0x03)
[ 132.325158] serial_out(ffffffffb6b980a0, 0x05, 0x00)
[ 132.325162] serial_out(ffffffffb6b980a0, 0x00, 0x83)
[ 132.325165] serial_out(ffffffffb6b980a0, 0x01, 0x02)
[ 132.325169] serial_out(ffffffffb6b980a0, 0x04, 0x88)
[ 132.325175] serial_out(ffffffffb6b980a0, 0x04, 0x8b)
[ 132.325245] serial_out(ffffffffb6b980a0, 0x07, 0x02)
[ 132.325251] serial_out(ffffffffb6b980a0, 0x05, 0x08)
[ 132.325254] serial_out(ffffffffb6b980a0, 0x07, 0x01)
[ 132.325257] serial_out(ffffffffb6b980a0, 0x05, 0x1f)
[ 132.325261] serial_out(ffffffffb6b980a0, 0x07, 0x03)
[ 132.325264] serial_out(ffffffffb6b980a0, 0x05, 0x00)
[ 132.325267] serial_out(ffffffffb6b980a0, 0x00, 0x69)
[ 132.325271] serial_out(ffffffffb6b980a0, 0x01, 0x00)
[ 132.325274] serial_out(ffffffffb6b980a0, 0x04, 0x8b)
[ 132.325377] serial_out(ffffffffb6b980a0, 0x01, 0x07)
[ 132.325385] serial_in(ffffffffb6b980a0, 0x05) -> 0x60
[ 132.325389] serial_out(ffffffffb6b980a0, 0x00, 0x55)
[ 132.325393] serial_out(ffffffffb6b980a0, 0x01, 0x05)
[ 132.325623] serial_in(ffffffffb6b980a0, 0x05) -> 0xe9
[ 132.325633] serial_in(ffffffffb6b980a0, 0x00) -> 0x78
[ 132.325640] serial_in(ffffffffb6b980a0, 0x05) -> 0x60
[ 132.325647] serial_in(ffffffffb6b980a0, 0x06) -> 0xb0
[ 132.325758] serial_in(ffffffffb6b980a0, 0x05) -> 0xe9
[ 132.325768] serial_in(ffffffffb6b980a0, 0x00) -> 0x1e
[ 132.325773] serial_in(ffffffffb6b980a0, 0x05) -> 0x60
[ 132.325780] serial_in(ffffffffb6b980a0, 0x06) -> 0xb0
[ 132.325935] serial_in(ffffffffb6b980a0, 0x05) -> 0xe9
[ 132.325943] serial_in(ffffffffb6b980a0, 0x00) -> 0x78
[ 132.325948] serial_in(ffffffffb6b980a0, 0x05) -> 0x60
[ 132.325955] serial_in(ffffffffb6b980a0, 0x06) -> 0xb0
[ 132.326602] serial_in(ffffffffb6b980a0, 0x05) -> 0x61
[ 132.326610] serial_in(ffffffffb6b980a0, 0x00) -> 0xfe
[ 132.326615] serial_in(ffffffffb6b980a0, 0x05) -> 0x60
[ 132.326622] serial_in(ffffffffb6b980a0, 0x06) -> 0xb0
[ 132.473966] serial_in(ffffffffb6b980a0, 0x05) -> 0x60
[ 132.473978] serial_out(ffffffffb6b980a0, 0x04, 0x88)
[ 132.473990] serial_out(ffffffffb6b980a0, 0x04, 0x80)
[ 132.473996] serial_out(ffffffffb6b980a0, 0x02, 0x01)
[ 132.474000] serial_out(ffffffffb6b980a0, 0x02, 0x07)
[ 132.474004] serial_out(ffffffffb6b980a0, 0x02, 0x00)
Also I have identified a code piece that handles the EFR in a destructive
manner, which I must have previously missed, namely a conditional block
guarded by UART_CAP_EFR in `serial8250_do_set_termios'. It should likely
be fixed, however it is supposed not to matter for OxSemi chips due to:
/* UART_CAP_EFR breaks billionon CF bluetooth card. */
.flags = UART_CAP_FIFO | UART_CAP_SLEEP,
which then leads to:
serial 0000:07:00.3: detected caps 00000700 should be 00000500
and consequently UART_CAP_EFR gets cleared and this code block isn't
supposed to be reached. Can you confirm the presence of a similar message
in your log?
Can not see any such message in my dmsg
NB it seems to me too big a hammer to have a generic serial port feature
globally disabled to work around an unidentified problem with an attached
particular serial device. Pavel, as the originator of commit d0694e2aeb81
("serial: unbreak billionton CF card") can you please explain what the
motivation was here?
I could only track down two message threads related to the problem:
<https://lore.kernel.org/lkml/20110106134254.68fa27ac@xxxxxxxxxxxxxxxxxxx/>
and:
<https://lore.kernel.org/linux-serial/4D001AF1.80902@xxxxxxxxxxxx/>
but no attempt to actually narrow the issue down (also ISTM like a feature
such as flow control ought to be controlled via a termios call rather than
globally disabled). Also could the corruption of the EFR in what is now
`serial8250_do_set_termios' (and used to be `serial8250_set_termios' then)
mentioned above be the culprit?
/Anders
--
Anders Blomdell Email: anders.blomdell@xxxxxxxxxxxxxx
Department of Automatic Control
Lund University Phone: +46 46 222 4625
P.O. Box 118
SE-221 00 Lund, Sweden
