Re: RFC: outb 0x80 in inb_p, outb_p harmful on some modern AMD64 with MCP51 laptops

below, from a list of those I needed to patch to eliminate refs to _b
calls) or arch specific code (also listed below), who might know why the
_p macros are actually needed (for any platform)?

Because the controllers were historically slower than the CPU and thus
clocked at half bus speed. Various chipsets simply shrank the logic
without fixing this.

Note that many of the devices are not on the ISA/LPC bus now, even if
they were, and the vga has never needed a bus-level pause since the
original IBM PC existed. (it did need a sync with retrace, but that's
another story).

Sync with retrace is MDA memory updates.

The vga driver is somewhat misnamed. In console mode we handle everything
back to MDA/HGA and some HGA adapters do need delays.

2) Why are opterons and so forth so slow on out's to x80 as the
measurements show? That seems to me like there is a hidden bus timeout

Because the LPC bus cycles are run at ISA speed.

I do remind all that 0x80 is a BIOS-specific standard, and is per BIOS -
other ports have been used in the history of the IBM PC family by some
vendors, and some machines have used it for DMA port mapping!! And

All do -thats why it is suitable.

Windows XP does NOT use it at all. Therefore it may not be supported by

Older Windows does. Don't know about XP although DOS apps in XP will but
they may virtualise the port.

I have a simple patch that fixes my primary concern - just change the
CMOS_READ and CMOS_WRITE, 64-bit versions of I/O and bootcode vga
accesses (first group below) to use the straight inb and outb code.

Which requires care. Have you verified all the main chipset vendors ?

I may submit it so that the many others who share my pain will be made

All .. none of them ?

I can do some of these off the top of my head

drivers/net/8390.h

Needed for some 8390 devices on ISA bus

drivers/net/de600.c
drivers/net/de600.h

Uses the parallel port which isnt guaranteed to be full ISA speed.

drivers/scsi/ppa.h

Parallel port

drivers/serial/8250.c

Some PC's need delays for certain ops.

drivers/watchdog/wdt_pci.c

That one is a mistake I believe, I'll dig out the docs.

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

Relevant Pages

  • Re: Parallel port filter - what is a MicrosoftRawPort?
    ... Parallel.sys is a bus driver. ... It not only controls the parallel port but ... devices attached to the parallel port. ... you have to write a bus filter. ...
    (microsoft.public.development.device.drivers)
  • Re: banging a printer port
    ... aren't you limited by the bus speed? ... Now what I'm not sure about is, my parallel port for instance is a PCI ...
    (sci.electronics.design)
  • usb_insert_transfer panic with if_zyd
    ... When I use my ZyXEL G-220 Wireless USB Stick with the if_zyd driver, ... <ACPI PCI bus> on pcib0 ... device problem, disabling port 1 ... <Ethernet over FireWire> on firewire0 ...
    (freebsd-current)
  • cd drive problems when trying to play an audio cd on 5.1
    ... acpi0: power button is handled as a fixed feature programming model. ... <ACPI PCI bus> on pcib0 ... <Parallel port bus> on ppc0 ... on ppbus0 ...
    (freebsd-questions)
  • kernel panic on 5.4-RELEASE-p6
    ... # Floating point support - do not disable. ... # PCI Ethernet NICs that use the common MII bus controller code. ... configured irq 4 not in bitmap of probed irqs 0 ... port may not be enabled ...
    (freebsd-stable)
Loading