Re: [U-Boot-Users] MPC83xx - previous patch to set MBAR
On Wed, 1 Aug 2007 15:20:22 -0500 "Keith Mund" keith.mund@clearcube.com wrote:
There was a u-boot 1.1.3 patch for start.S posted on the Freescale LTIB
posts concerning u-boot should go to the u-boot-users list (cc'd).
site: http://www.bitshrine.org/gpp/u-boot-1.1.3-mpc83xx-cpu-4.patch
The end result simply adds a line to set MBAR to match IMMRBAR.
lis r3, CFG_IMMRBAR@h ori r3, r3, CFG_IMMRBAR@l stw r3, IMMRBAR(r4)
mtspr MBAR, r3Are these patches routinely added to the mainstream u-boot code?
Is there any reason why this fix is not a good idea?
does setting MBAR really fix anything?
MBAR doesn't live up to its name. It's a general-purpose scratch register - the hardware doesn't do anything with it. So, wrt integrity within u-boot itself, I see no point/value in setting it. If some piece of software needs temporary storage, it can set it and use it as it wishes, independent of u-boot.
Kim
The end result simply adds a line to set MBAR to match IMMRBAR.
lis r3, CFG_IMMRBAR@h ori r3, r3, CFG_IMMRBAR@l stw r3, IMMRBAR(r4)
mtspr MBAR, r3Are these patches routinely added to the mainstream u-boot code?
Is there any reason why this fix is not a good idea?
does setting MBAR really fix anything?
MBAR doesn't live up to its name. It's a general-purpose scratch register - the hardware doesn't do anything with it. So, wrt
Kim is right.
MBAR setting is added by two years ago, it is not really fix anything.
I set the MBAR to be easier to use the CodeWarriror. The CodeWarrior must set the MBAR first, then it will be able to access the IMMR.
Dave
This was to the wrong group.
Thanks for the responses and the clarification. The "needed for CodeWarrior only" part is what I suspected.
Keith Mund
-----Original Message----- From: linuxppc-dev-bounces+alfman=austin.rr.com@ozlabs.org [mailto:linuxppc-dev-bounces+alfman=austin.rr.com@ozlabs.org] On Behalf Of Liu Dave-r63238 Sent: Wednesday, August 01, 2007 9:15 PM To: Phillips Kim-R1AAHA; Keith Mund Cc: linuxppc-dev@ozlabs.org; u-boot-users@lists.sourceforge.net Subject: RE: [U-Boot-Users] MPC83xx - previous patch to set MBAR
The end result simply adds a line to set MBAR to match IMMRBAR.
lis r3, CFG_IMMRBAR@h ori r3, r3, CFG_IMMRBAR@l stw r3, IMMRBAR(r4)
mtspr MBAR, r3Are these patches routinely added to the mainstream u-boot code?
Is there any reason why this fix is not a good idea?
does setting MBAR really fix anything?
MBAR doesn't live up to its name. It's a general-purpose scratch register - the hardware doesn't do anything with it. So, wrt
Kim is right.
MBAR setting is added by two years ago, it is not really fix anything.
I set the MBAR to be easier to use the CodeWarriror. The CodeWarrior must set the MBAR first, then it will be able to access the IMMR.
Dave _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-dev
On Thu, Aug 02, 2007 at 10:14:31AM +0800, Liu Dave-r63238 wrote:
MBAR doesn't live up to its name. It's a general-purpose scratch register - the hardware doesn't do anything with it. So, wrt
That doesn't mean there isn't value in setting it, so code can easily find the IMMR without having to parse the device tree.
-Scott
On Aug 2, 2007, at 10:28 AM, Scott Wood wrote:
On Thu, Aug 02, 2007 at 10:14:31AM +0800, Liu Dave-r63238 wrote:
MBAR doesn't live up to its name. It's a general-purpose scratch register - the hardware doesn't do anything with it. So, wrt
That doesn't mean there isn't value in setting it, so code can easily find the IMMR without having to parse the device tree.
It could be, but there isn't really any value in doing this since its in the device-tree and we have to find it for 85xx, 86xx, and pretty much all our parts.
- k
participants (5)
-
Alfred Manheim -
Kim Phillips -
Kumar Gala -
Liu Dave-r63238 -
Scott Wood