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Re: Linux kernel 2.6.20, PCI and hpt266

To: Marco Braga <marco.braga@gmail.com>
Subject: Re: Linux kernel 2.6.20, PCI and hpt266
From: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Date: Mon, 05 Mar 2007 15:42:05 +0300
Cc: linux-mips@linux-mips.org
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Hello.

Marco Braga wrote:

Hello, I am trying to run kernel 2.6.20 on an Au1500 based board. Versions
2.4.x of the kernel are correctly working.

   How could they work I wonder? :-O

Problem: on the board there is a HighPoint 371N ATA controller. At the

   There's *no* proper support for HPT371N in 2.4.x.

moment the kernel 2.6.20 boots and runs, but the ATA controller does not
recognize the IDE disk.

Details:
The driver I use is "drivers/ide/pci/hpt266.c". I've already fixed the

   I guess you mean hpt366.c. :-)

timing problems and PLL configuration that afflict this controller, and
removed RESOURCE_64BIT to fix problems with the PCI bus on mips and
resource_size_t casts.

   Erm, does it indeed fix the problem I wonder?

I've managed to follow the problem to ide-probe.c, in function
"actual_try_to_identify". It seems that the values read from the ATA
registers through IO ports are not correct. As every ATA controller, it
needs 8 bytes in IO port space for Command Block registers, and 4 bytes for
the Control Block registers. They are mapped by the kernel at:

1400-1407 (8 bytes) Command block channel 0
1408-140F (8 bytes) Command block channel 1
1410-1413 (4 bytes) Control block channel 0
1414-1417 (4 bytes) Control block channel 1

Notice that Highpoint 371N has registers for 2 channel, but the pinout for
only 1 channel. In fact the first channel is disabled by the driver, so the
actual registers are in the range 1408-140F and 1414-1417. The first sign of
the problem is that INB do not read the correct values for the ALTSTATUS
register. In fact the kernel reports:

... probing with STATUS(...) instead of ALTSTATUS(...)

[as in ide-probe.c, line 290]

The values read from the ATA registers are completely wrong. The registers
are accessed through hwif->INB, that are common "inb" functions. This makes
me suspect that "inX" functions are not working, but I don't know how to
test this. Notice that the PCI controller configuration space is correctly
accessed, as I can confirm reading sys/bus/pci/.../config.

The PCI config. space accesses use completely different meachanism form I/O and memory accesses.

Can you help or suggest me anything?

   Well, I guess I'll try the current kernel on one of my DBAu1x00 boards...

Thanx!

WBR, Sergei

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