Re: [PATCH] Resurrect IT8172 IDE controller driver

From: Sergei Shtylyov
Date: Thu Dec 04 2008 - 11:10:33 EST


Shane McDonald wrote:

Alan Cox wrote:

It's 240, not 242 ns as 33 is actually 33.333.

The maximum values give cycle time of 480 ns menaing that the controller
doesn't support PIO mode 0. Hm...

Even if you clear the enable for the timing register ?

These fast timing bits are documented as reserved.

The spec says that PIO mode 0 is supported, but Sergei is correct --
the maximum values give a cycle time of 480 ns. How can this be? The
old driver appeared to have tried to support PIO mode 0 by setting to
the maximum.

Which fast timing bits are documented as reserved? My spec has the
IDE Drive 0/1 Recovery Time and IDE Drive 0/1 Pulse Width bits in it.
Are there other timing bits that aren't documented in my spec?

Off the top of my head: bits 0, 3, 4, and 7 at offset 0x40 are not reserved in PIIX/ICH -- they enable the programmable timings for PIO and/or DMA. If they were left cleared, 600 ns cycle (PIO mode 0) was used.

Please excuse my dumb question -- I'm a little over my head here.



MBR, Sergei
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