Re: puc(4) man page update?

On Jul 1, 2008, at 11:13 AM, Alexey Shuvaev wrote:

> Hello!
>
> I have got
> puc0_at_pci0:0:10:0:       class=0x078000 card=0x00121000  
> chip=0x98359710 rev=0x01 hdr=0x00
>    vendor     = 'MosChip Semiconductors (Was: Netmos Technology)'
>    device     = 'Nm9835 Parallel/Serial Port Adapter'
>    class      = simple comms
>
> In a nutshell I have the following proposals to review:
>
> - I have spent few hours figuring out why serial interfaces
>  covered by puc(4) do not come up at boot time. The issue was I tried
>  to use kernel module instead of compiling puc(4) into the kernel.
>  Will it be good to have explicit note about it in the man page?

Well, no. There's a very simple rule:

If driver C is a child of a driver P and driver P is
loaded as a module, then driver C must be loaded as
a module as well.

In this case uart(4) and ppc(4) are children of puc(4)
and both are compiled into the kernel by default. So,
you must either compile puc(4) into the kernel or
build uart(4) and puc(4) as modules as well.

In other words: there's no problem with puc(4) being
loaded as a module. It's a generic problem with our
modules vs. compiled-in case.

> - First time when I rebuilt the kernel I only added
>  options COM_MULTIPORT, which is used inside sio(4). The puc(4) also  
> states
>  the serial ports are managed by sio(4). However it seems that serial
>  ports are actually handled by uart(4). Is COM_MULTIPORT kernel option
>  obsolete?

COM_MULTIPORT is specific to sio(4), so yes it's obsolete.

puc(4) favors uart(4) over sio(4), because both puc(4) and
uart(4) implement the serdev I/F, which gives puc(4) better
control over which port gets to service what interrupt
condition in what relative order. In other words, it allows
puc(4) to handle all receive interrupts of all ports before
it handles any transmit interrupts.

With sio(4) there's no benefit.

> - The puc(4) man page states parallel ports are not supported yet.
>  It seems thay did now.

Parallel ports are supported, yes.

> Attached is a draft of a patch to share/man/man4/puc.4 but maybe more
> work is required (regarding COM_MULTIPORT and sio(4) man page...).

I would not mention COM_MULTIPORT in the puc(4) manpage
at all. Neither sio(4)...

FYI,

-- 
Marcel Moolenaar
xcllnt_at_mac.com