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Peter Korsgaard wrote:
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<pre wrap="">"David" == David H Lynch <a class="moz-txt-link-rfc2396E" href="mailto:dhlii@dlasys.net"><dhlii@dlasys.net></a> writes:
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Hi,
David> Peter's driver uses the IORESOURCE requests to pull platform
David> data. Most other serial platformdevices pull a uart_port
David> object. My limited understanding of IORESOURCE is that it is
David> not sufficiently deep to support the parameters that are needed
David> to support UartLite such as a DCR flag and a regoffset.
I'm still not convinced that DCR access and variable register offsets
are needed - But it can always be added (through a seperate struct in
platform_data) - Patches are welcome.
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It does not matter whether you or I are convinced. It matters
whether there are people that need it.<br>
Xilinx has a reference design that uses DCR. While I have never
tripped over an actual implimentation that uses<br>
DCR there are others on this list that have.<br>
<br>
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The same with interrupt-less support if the changes are not too
intrusive.
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Right now I can not get your driver to work. I spent alot of time
trying to fix it and got nowhere.<br>
I can not get it to receive at all, and I can not get it to send
after switching from the console driver<br>
without dropping characters. I am very busy with other things right
now and it is going to be a long <br>
time before I have time to look at your driver again.<br>
<br>
In the meantime, my own driver works - atleast for me. And it is
out in the real world on production systems.<br>
<br>
The most instrusive changes is likely to be fixing whatever is
causing yours to drop characters - the problem is <br>
worse when I patch your driver to be timer driven - but that is
likely because your service routines blindly presume it is <br>
safe to transmit - true on a Tx empty interrupt, but not on a
timer tick.<br>
<br>
But what matters is not whether the changes are intrusive, but
whether they produce a better result.<br>
<br>
<br>
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<pre wrap="">David> You are welcome to do that. I already patched his driver to
David> work with my early console support as well as adding the
David> boot-bash stuff similar to yours. But I gave up actually using
David> it when I could not get it to work.
Which is odd as I've gotten positive feedback from others.
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I am glad somebody is using your driver and finding it works. But
we are all better served by fixing the failure cases.<br>
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It is not particularly odd at all. The UartLite despite its
simplicity is worse than a normal driver - different<br>
FPGA implimentations can vary. Normal drivers for fixed inflexible
hardware often do not work accross<br>
differing implimentations, why would you expect something like
UartLite to be invariant ?<br>
<br>
One of the other reasons for implimenting polling is because a
polled driver tends to work accross <br>
wider hardware variations. You can not make state assumptions in a
poll routine, <br>
and if the poll routine does nto run then the rest of the OS is
hosed.<br>
<br>
Even today, flakey hardware interrupts are not unheard of. <br>
<br>
I would also ask what data rates you and others with Working
UartLites are using ?<br>
The cases I am dealing with run at 57600 and 115200 respectively -
it is not that odd for <br>
driver problems to manifest themselves only or more frequently at
high baud rates.<br>
<br>
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David> Next time I get an opportunity I am going to try to setup an
David> ml403 to atleast verify that Peter's driver is working there.
Great.
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Without being difficult - don't hold your breath. It is something I
would like to do, but<br>
I do not have infinite time.<br>
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<pre class="moz-signature" cols="72">--
Dave Lynch DLA Systems
Software Development: Embedded Linux
717.627.3770 <a class="moz-txt-link-abbreviated" href="mailto:dhlii@dlasys.net">dhlii@dlasys.net</a> <a class="moz-txt-link-freetext" href="http://www.dlasys.net">http://www.dlasys.net</a>
fax: 1.253.369.9244 Cell: 1.717.587.7774
Over 25 years' experience in platforms, languages, and technologies too numerous to list.
"Any intelligent fool can make things bigger and more complex... It takes a touch of genius - and a lot of courage to move in the opposite direction."
Albert Einstein
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