RE: Megaraid: Use of outb_p

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Alan/Matthew,

I found inb_p/outb_p are defined as inb/outb in kernel src.  So it
should not have problems to change inb_p/outb_p to inb/outb.

Thanks.

Bo Yang 


-----Original Message-----
From: Matthew Wilcox [mailto:matthew@xxxxxx] 
Sent: Friday, January 18, 2008 3:41 PM
To: Yang, Bo
Cc: Alan Cox; linux-scsi@xxxxxxxxxxxxxxx; DL-MegaRAID Linux
Subject: Re: Megaraid: Use of outb_p

On Fri, Jan 18, 2008 at 01:32:12PM -0700, Yang, Bo wrote:
> Alan,
> 
> The in/outb_p in MegaRAID scsi driver is used for our old io mapped 
> megaraid controller.  There are still some customers are using those 
> old controller.  Please keep them.

Hi Bo,

I think you've misunderstood the question.  The '_p' versions of
inb/outb introduce a delay after each access.  The current Linux
implementation of _p provokes bugs on some chipsets, so Alan is looking
for alternatives.  Let's ask the question like this:

Replacing outb_p() with outb(); udelay(x); How large does 'x' need to be
for these megaraid controllers?

> Thanks.
>  
> Bo Yang
> 
> -----Original Message-----
> From: Alan Cox [mailto:alan@xxxxxxxxxxxxxxxxxxx]
> Sent: Friday, January 18, 2008 7:36 AM
> To: linux-scsi@xxxxxxxxxxxxxxx; DL-MegaRAID Linux
> Subject: Megaraid: Use of outb_p
> 
> 
> I notice the MegaRAID driver uses outb_p. Can someone at LSI confirm 
> that the delays between each I/O are required, and if so how long they

> must be.
> 
> I'm trying to sort out the use of in/outb_p and where it is 
> unneccessary or used for non ISA devices.
> 
> (Please cc me on the reply)
> Alan
> 
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