Date:	Fri, 18 Sep 2015 11:24:05 +0200
From:	"Wolfgang Wilhelm" <wilhelm@...tcomtec.com>
To:	stable@...r.kernel.org, Austin S Hemmelgarn <ahferroin7@...il.com>,
	Greg KH <greg@...ah.com>
CC:	linux-kernel@...r.kernel.org
Subject: Re: problem with "serial" driver in kernel 3.16.0

Thankyou very much for your quick answers. I searched now
in the linux sources for the problem and I think I could find it
in the file linux-source-3.16/drivers/tty/serial/8250/8250_pci.c

There is a function serial_pci_guessboard and a blacklist
including the vendor- and device-ids of 3 softmodems and 
2 multi-io cards. I think if the vendor id 0x10e8 (standard AMCC)
and device id 0x8226 could be inserted into that blacklist
I could load our driver and get the software for our MPA-3 
multiparameter system working. It seems that these id's are 
not really used by any existing serial card, but this guessboard 
function anyway takes our card as a serial board.

Is this a matter of the Debian distribution or the general linux kernel?

Best regards,
Wolfgang Wilhelm



Betreff:	Re: problem with "serial" driver in kernel 3.16.0
An:	Wolfgang Wilhelm <wilhelm@...tcomtec.com>, stable@...r.kernel.org
Kopie an:	linux-kernel@...r.kernel.org
Von:	Austin S Hemmelgarn <ahferroin7@...il.com>
Datum:	Thu, 17 Sep 2015 16:03:52 -0400

On 2015-09-17 09:24, Wolfgang Wilhelm wrote:
> We are a small company FAST ComTec GmbH
> (www.fastcomtec.com) and produce multichannel analyzers
> with Windows software. I am the software developer and
> would like to get our software working also under Linux
> with the help of WINE.
Before I go any further, I would like to thank you for even
considering 
this option.  If there were more vendors who tried this, Linux would
have much better support for quite a large number of hardware
devices.

> I was already successfull with our USB devices and most
> of our PCI cards, but with one of the PCI cards
> it does not work (in Debian v8, kernel 3.16.0).
>
> Our PCI cards have a AMCC controller S5933, we use the
> standard AMCC vendor id 0x10e8 and device id 0x8226,
> device class serial. Most of our cards use two I/O port ranges
> and an interrupt. I have written a linux driver for these cards
> and could get everything working, but the interface card
> for our MPA-3 multiparameter system uses only
> one I/O port range and an interrupt. This card is recognized
> by the "serial" driver in the kernel as a serial interface card
> and there is no way to load our own driver.
>
> My question is, could you remove in future kernel versions
> the support for this card in the kernel our make it possible
> to blacklist it in /etc/modprobe.d/fbdev-blacklist.conf
> like other drivers that are not directly included in the kernel?

Removal is probably not an option (if there is a kernel driver for the
chip already, there are almost certainly other drivers that use this
chip).  As far as blacklisting goes, that would be something to take
up with the distribution you are developing for (so Debian from what
you've said), although you may not get much help there either if the driver
isn't open source.  In general, it's better to either get your driver
in the kernel at the source code level (which in turn includes help with
ABI updates on the kernel side), or find some way to write it entirely
in userspace (I'd suggest lucking at either the VFIO subsystem or the
older userspace driver framework for this).


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