Serial port numbering (ttyS..) wrong for 2.5.61+

Serial port numbering (ttyS..) wrong for 2.5.61+

[Ruud Linders]

Since I tried the 2.5 kernel versions somewhere in the 2.5.6x range, I
see rather odd port naming for the extra 4 serial ports on a PCI-card.

The first two are numered as ttyS14, ttyS15 while the last two are
ttyS2 and ttyS3 !
I tried to find where these numbers are coming from but couldn't really
find an obvious place in the various drivers/char/* or drivers/serial/*
files.

Note that the ttyS14 port actually works so this seems only a bug in
the numbering.

Regards,
Ruud Linders


Kernel version 2.5.70
---------------------
dmesg:
======
Serial: 8250/16550 driver $Revision: 1.90 $ IRQ sharing enabled
ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A
ttyS1 at I/O 0x2f8 (irq = 3) is a 16550A
ttyS14 at I/O 0xbc00 (irq = 21) is a 16550A     <<<<<<  14 ????
ttyS15 at I/O 0xbc08 (irq = 21) is a 16550A     <<<<<<
ttyS2 at I/O 0xbc10 (irq = 21) is a 16550A
ttyS3 at I/O 0xbc18 (irq = 21) is a 16550A

4-port PCI serial controller:
=============================
# lspci -d 10b5:1077 -v
02:0b.0 Serial controller: PLX Technology, Inc. VScom 400 4 port serial 
adaptor
(rev 02) (prog-if 00 [8250])
         Subsystem: PLX Technology, Inc. VScom 400 4 port serial adaptor
         Flags: medium devsel, IRQ 21
         Memory at de004000 (32-bit, non-prefetchable) [size=128]
         I/O ports at b800 [size=128]
         I/O ports at bc00 [size=32]
         I/O ports at c000 [size=8]
         Expansion ROM at <unassigned> [disabled] [size=2K]

Re: Serial port numbering (ttyS..) wrong for 2.5.61+

[Paul Rolland]

Hello,

> Since I tried the 2.5 kernel versions somewhere in the 2.5.6x range, I
> see rather odd port naming for the extra 4 serial ports on a PCI-card.
Which driver are you using ?

> The first two are numered as ttyS14, ttyS15 while the last two are
> ttyS2 and ttyS3 !
> I tried to find where these numbers are coming from but 
> couldn't really
> find an obvious place in the various drivers/char/* or 
> drivers/serial/*
> files.

Numbering seems to be coming out of 
drivers/serial/core.c : uart_find_match_or_unused
which is responsible for finding an unused state for the port.

However, the code there seems to be clean and I guess we should look
where the state are initialized.

Paul

Re: Serial port numbering (ttyS..) wrong for 2.5.61+

[Russell King]

On Sun, Jun 01, 2003 at 02:48:14PM +0200, Paul Rolland wrote:
> Numbering seems to be coming out of 
> drivers/serial/core.c : uart_find_match_or_unused
> which is responsible for finding an unused state for the port.
> 
> However, the code there seems to be clean and I guess we should look
> where the state are initialized.

When we add a port to the system, we try to find in order:

- a port which matches the base address
- a port which is unallocated

Probably the easiest way to stop the "ttyS14" occuring would be to
clear the port information at boot when we don't find a port.

-- 
Russell King (rmk@arm.linux.org.uk)                The developer of ARM Linux
             http://www.arm.linux.org.uk/personal/aboutme.html

Re: Serial port numbering (ttyS..) wrong for 2.5.61+

[Paul Rolland]

Hello,


> When we add a port to the system, we try to find in order:
> 
> - a port which matches the base address
> - a port which is unallocated
> 
> Probably the easiest way to stop the "ttyS14" occuring would 
> be to clear the port information at boot when we don't find a port.
> 
>From 8250_pci.c, you have :

/*              
 * Probe one serial board.  Unfortunately, there is no rhyme nor reason
 * to the arrangement of serial ports on a PCI card.
 */             

It seems that your board is reporting the parameters in such an order
that when looking for a port based on the IRQ, I/O port, ... the matching
one has id 14...

You could see this more clearly by setting SERIAL_DEBUG_PCI
at line 1549 to activate the code :
#ifdef SERIAL_DEBUG_PCI
                printk("Setup PCI port: port %x, irq %d, type %d\n",
                       serial_req.port, serial_req.irq, serial_req.io_type);
#endif

that would report to you the order in which ports are found on
your system.

Regards,
Paul

Re: Serial port numbering (ttyS..) wrong for 2.5.61+

[Ruud Linders]

Paul,

Setting SERIAL_DEBUG_PCI gives me this:

Serial: 8250/16550 driver $Revision: 1.90 $ IRQ sharing enabled
ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A
ttyS1 at I/O 0x2f8 (irq = 3) is a 16550A
Setup PCI port: port bc00, irq 21, type 0
ttyS14 at I/O 0xbc00 (irq = 21) is a 16550A
Setup PCI port: port bc08, irq 21, type 0
ttyS15 at I/O 0xbc08 (irq = 21) is a 16550A
Setup PCI port: port bc10, irq 21, type 0
ttyS2 at I/O 0xbc10 (irq = 21) is a 16550A
Setup PCI port: port bc18, irq 21, type 0
ttyS3 at I/O 0xbc18 (irq = 21) is a 16550A

Doesn't give us much more detail.

BTW, this is the entry in 8250_pci.c for the board in question:
        {       PCI_VENDOR_ID_PLX, PCI_DEVICE_ID_PLX_1077,
                PCI_ANY_ID, PCI_ANY_ID, 0, 0, 
                pbn_b2_4_921600 },

Note that the ttyS's _are_ numbered in sequence in 2.4.20


On Mon, Jun 02, 2003 at 08:43:24PM +0200, Paul Rolland wrote:
> Hello,
> 
> 
> > When we add a port to the system, we try to find in order:
> > 
> > - a port which matches the base address
> > - a port which is unallocated
> > 
> > Probably the easiest way to stop the "ttyS14" occuring would 
> > be to clear the port information at boot when we don't find a port.
> > 
> >From 8250_pci.c, you have :
> 
> /*              
>  * Probe one serial board.  Unfortunately, there is no rhyme nor reason
>  * to the arrangement of serial ports on a PCI card.
>  */             
> 
> It seems that your board is reporting the parameters in such an order
> that when looking for a port based on the IRQ, I/O port, ... the matching
> one has id 14...
> 
> You could see this more clearly by setting SERIAL_DEBUG_PCI
> at line 1549 to activate the code :
> #ifdef SERIAL_DEBUG_PCI
>                 printk("Setup PCI port: port %x, irq %d, type %d\n",
>                        serial_req.port, serial_req.irq, serial_req.io_type);
> #endif
> 
> that would report to you the order in which ports are found on
> your system.
> 
> Regards,
> Paul
> 
> 
> -
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Re: Serial port numbering (ttyS..) wrong for 2.5.61+

[Ruud Linders]

 >>Hello,
 >
 >> Since I tried the 2.5 kernel versions somewhere in the 2.5.6x range, I
 >> see rather odd port naming for the extra 4 serial ports on a PCI-card.
 >Which driver are you using ?

See attached CONFIG_SERIAL* from my config, this is the 'standard'
serial port driver.

 >
 >> The first two are numered as ttyS14, ttyS15 while the last two are
 >> ttyS2 and ttyS3 !
 >> I tried to find where these numbers are coming from but
 >> couldn't really
 >> find an obvious place in the various drivers/char/* or
 >> drivers/serial/*
 >> files.
 >
 >Numbering seems to be coming out of
 >drivers/serial/core.c : uart_find_match_or_unused
 >which is responsible for finding an unused state for the port.
 >
 >However, the code there seems to be clean and I guess we should look
 >where the state are initialized.
 >
 >Paul


==============================================================

# CONFIG_SERIAL_NONSTANDARD is not set

#
# Serial drivers
#
CONFIG_SERIAL_8250=y
CONFIG_SERIAL_8250_CONSOLE=y
CONFIG_SERIAL_8250_EXTENDED=y
CONFIG_SERIAL_8250_MANY_PORTS=y
CONFIG_SERIAL_8250_SHARE_IRQ=y
# CONFIG_SERIAL_8250_DETECT_IRQ is not set
CONFIG_SERIAL_8250_MULTIPORT=y
# CONFIG_SERIAL_8250_RSA is not set

#
# Non-8250 serial port support
#
CONFIG_SERIAL_CORE=y
CONFIG_SERIAL_CORE_CONSOLE=y