Discussion:
Mesa 7i90 and 7i43 EPP mode
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Bertho Stultiens
2017-06-13 13:57:30 UTC
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Hi,

Is there a way to detect the difference between the 7i90 and 7i43 boards
over EPP communication? I was looking into these drivers and they are
essentially the same (very small difference if you take the variable
naming out of the picture).

I have been pondering to add yet another RPI driver doing EPP emulation
on the GPIO pins. It would at least as fast as SPI communication and has
the potential to be faster (especially if the EPP slave relaxes the
timing a bit).

The advantage of EPP emulation is in the reduced frequency on the
pysical communication lines and would be at least four times lower. The
physical bottleneck would be on strobe-timing. That may be an advantage
in noisy environments and the overhead on the RPI is not any greater
than using SPI (which is also polled in a busy-loop).

If both 7i90 and 7i43 can be differentiated over EPP at runtime, then a
unified EPP driver is more easily created. Otherwise you need a module
parameter to distinguish or duplicate most of the code.

Any comments, thoughts or suggestions?
--
Greetings Bertho

(disclaimers are disclaimed)
andy pugh
2017-06-13 14:16:15 UTC
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Post by Bertho Stultiens
If both 7i90 and 7i43 can be differentiated over EPP at runtime, then a
unified EPP driver is more easily created.
I think I once saw a hm2_epp driver, I wonder where it went?
--
atp
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Peter C. Wallace
2017-06-13 14:46:59 UTC
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Date: Tue, 13 Jun 2017 15:57:30 +0200
Subject: [Emc-developers] Mesa 7i90 and 7i43 EPP mode
Hi,
Is there a way to detect the difference between the 7i90 and 7i43 boards
over EPP communication? I was looking into these drivers and they are
essentially the same (very small difference if you take the variable
naming out of the picture).
Yes, and I think there could be a unified driver for both

The reason the 7I43 driver doen't work with the 7I90 is that it assumes that
it needs to download firmware into the card at startup (So also fails with
7I43s that are set to load firmware from their local EEPROM)

Probably the best thing for the driver to do is assume that if the driver
command line has a firmware token, that it should download that firmware and
if not, assume the FPGA is loaded and probe for a valid HostMot2 cookie and
card name (firmware downloading direct to an unprogrammed FPGA is only
possible with the 7I43, not a 7I90)
I have been pondering to add yet another RPI driver doing EPP emulation
on the GPIO pins. It would at least as fast as SPI communication and has
the potential to be faster (especially if the EPP slave relaxes the
timing a bit).
The advantage of EPP emulation is in the reduced frequency on the
pysical communication lines and would be at least four times lower. The
physical bottleneck would be on strobe-timing. That may be an advantage
in noisy environments and the overhead on the RPI is not any greater
than using SPI (which is also polled in a busy-loop).
If both 7i90 and 7i43 can be differentiated over EPP at runtime, then a
unified EPP driver is more easily created. Otherwise you need a module
parameter to distinguish or duplicate most of the code.
Any comments, thoughts or suggestions?
--
Greetings Bertho
(disclaimers are disclaimed)
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