Re: [PATCH] x86_64: fix problems due to use of "outb" to port 80 on some AMD64x2 laptops, etc.

On 14-12-07 14:15, Ingo Molnar wrote:

wow, cool fix! (I remember that there were other systems as well that are affected by port 0x80 muckery - i thought we had removed port 0x80 accesses long ago.)

how about the simpler fix below, as a first-level approach? We can then remove the _p in/out sequences after this.

Your version does the same thing that the version from Pavel/David does for 32-bit at least.

+/*
+ * Some legacy devices need delays for IN/OUT sequences. Most are
+ * probably not needed but it's the safest to just do this short delay:
+ */
+void native_io_delay(void)
+{
+	udelay(1);
+}

Also note the thread(s) on LKML where 2 us was decided to be a nicely conservative value:

http://lkml.org/lkml/2007/12/12/309

Also see: http://lkml.org/lkml/2007/12/14/72

And also: http://lkml.org/lkml/2007/12/12/221

As such, please wait a bit for a fuller resolution. We're still discussing this.

Rene.
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