This is very, very useful information. Thanks.
Both asy.c and su_driver.c are very, very crufty, and (quite honestly)
suffer from some poor design. I'm rewriting much of my new uart
framework from scratch, but I'm ditching 82510 support, and I might even
require a FIFO. (I've not decided on that yet or not. My design is
starting to demonstrate behavior that there is no difference between a
fifo-less UART and a deep fifo apart from reliability/performance at
high baud rates.)
-- Garrett
Kevin Crowe wrote:
> Peter, Garrett,
>
> See my replied inline. Hopefully I haven't 'lied' without knowing
> it or confused you with anything. Sorry for the delay in getting
> back to you. I'm also out of the office Aug 23rd & 24th.
>
>
> Peter Memishian wrote:
>> [ CC'ing Kevin Crowe, as I think he's familiar with the sordid
>> history of
>> su_driver.c. This is well outside my area of expertise. ]
>>
>> > I started looking at su_driver.c. It should be be consolidated as
>> > well. But one area that gives me cause for concern is comments
>> and code
>> > referencing the Intel 82510 chip.
>> > > Is this chip found on any UltraSPARC hardware (or any hardware
>> that we
>> > need to support in OpenSolaris?)
>>
>> Hopefully Kevin can answer this.
>
> I am not aware of any UltraSPARC hardware that uses the 82510 chip? I
> believe that the only UltraSPARC chips that the 'su' driver drives
> are the Acer-Ali 1535 series of Southbridge chips. These chips claim
> to have 165xx compatible UART functionality inside them if I recall?
> (I don't have the spec sheets in front of me right now but they are
> easily found to confirm this.) I can't remember if Acer-Ali changed
> names or sold the 1535 rights to some other company so you may not
> find the specs at Acers website?
>
> There might be another brand of Southbridge that was used but I can't
> recall what it was? I believe it was also 165xx compatible.
>
> I have no experience with the 82510 chip nor have I ever seen it's
> data sheet.
>
>
> > I can either support the 82510 (I since found a datasheet), or (even
> > better) we can declare the chip unsupported.
> >
> > I would not be surprised to learn that the last 82510 platform was an
> > older sun4c or sun4m platform.
>
> I don't remember sun4c but some sun4m's used custom Sun built ASICS and
> used the zs serial port driver (Zilog 8530).
>
> Maybe sun4c or the antique i386 based stuff used the 82510? Thats way
> before my time though ;)
>
>
>
>> > I cannot find Intel's original datasheets for this part, and I'm not
>> > entirely confident in this part. It looks like it probably had a
>> FIFO,
>> > but that it was accessed using some method quite different from the
>> > standard 16550 UARTs.
>> > > Should I worry about this? I don't feel that I can support the
>> 82510
>> > without further knowledge of which platform(s) used it (so I can
>> test),
>> > and without a datasheet.
>> > > FWIW, it looks like once upon a time asy.c also had 82510
>> support that
>> > was removed in S10. I want to take it a step further and remove 8250
>> > and 16450, because I consider fifo-less UARTS to largely be
>> useless in
>
> I think it would be safer to leave the code in and just declare the
> chip(s) unsupported, clearly you can't introduce any regressions
> that way ;)
>
> By the way, su_driver.c was taken as a child of asy.c back around
> the Solaris 2.5.1 timeframe to be used as a keyboard/mouse driver.
> Around Solaris 8 timeframe the SunBlade 100 came along and used the
> Acer-Ali 1535 SuperIO chip and they chose to use the minimally
> maintained su driver (virtually no bugs were exposed since it was
> only a kbd/mouse driver) rather than port the x86 based asy.c driver
> to run on Sparc. asy.c was a bit better maintained since it was
> used on x86 (however due to the on-again-off-again x86 Sun support
> dance I'd guess it didn't get the best use and support over the years.)
> As such, much of su & asy are similar.
>
> su is still used for kbd/mouse on many/most sun4u based platforms
> (not the usb based kbd/mouse obviously.) I don't believe se or zs
> serial drivers are used at all and asy is only used on x86 so that
> leaves us with su as the only currently used generic serial port driver
> I'm aware of.
>
>
>
>> > the modern era.
>>
>> Clearly, removal of hardware support needs to be carefully researched to
>> ensure that we are not crippling any supported platforms. Kevin, can
>> you
>> clue us in on what serial chipsets need to be supported in Nevada?
>
> I believe only the Acer-Ali 1535 SuperIO chip with it's 16550 compabable
> serial ports is currently used. I wouldn't say I'm 100% positive but
> I don't recall running across anything else in our systems. I'm not
> overly familiar with all the Netra series of platforms though. I'm not
> aware of new systems in development and I guess it could be possible
> they might have plans to use a different chip driven by the su driver.
> I can only imagine that you'd have to track down PM's for all the
> different development groups to verify this?
>
> Thanks,
> Kevin.
--
Garrett D'Amore, Principal Software Engineer
Tadpole Computer / Computing Technologies Division,
General Dynamics C4 Systems
http://www.tadpolecomputer.com/
Phone: 951 325-2134 Fax: 951 325-2191
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