From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Scott Wood <scottwood@freescale.com>
Cc: Martyn Welch <martyn.welch@ge.com>, linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH] PowerPC: Remove hardcoded BAT configuration of IMMR in CPM early debug console
Date: Sat, 29 May 2010 13:37:13 +1000 [thread overview]
Message-ID: <1275104233.1931.523.camel@pasglop> (raw)
In-Reply-To: <4BFFECF1.9060809@freescale.com>
On Fri, 2010-05-28 at 11:18 -0500, Scott Wood wrote:
> Only the physical address should depend on where IMMR is. We should
> use
> fixmap instead of an arbitrary address for the effective address.
> There's a existing FIX_EARLY_DEBUG_BASE, but it's only 128 KiB so
> we'll
> have to either grow it, or map only a subset of IMMR.
>
> Plus, CONFIG_PPC_EARLY_DEBUG_CPM_ADDR points to the TX descriptor,
> not
> to the beginning of IMMR, so you should mask off the lower 20 bits
> (the
> offset is probably less than 64K, and the BAT might just ignore the
> extra bits anyway, but why take chances?).
BAT has other advantages such as limiting TLB usage for things that are
used often. I think we might want to revive Grant work on early ioremap
here :-)
Cheers,
Ben.
next prev parent reply other threads:[~2010-05-29 3:40 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-05-28 15:18 [PATCH] PowerPC: Remove hardcoded BAT configuration of IMMR in CPM early debug console Martyn Welch
2010-05-28 16:18 ` Scott Wood
2010-05-29 3:37 ` Benjamin Herrenschmidt [this message]
2010-06-01 12:52 ` Martyn Welch
2010-06-01 13:43 ` Martyn Welch
2010-06-01 16:06 ` Scott Wood
2010-06-02 8:06 ` Martyn Welch
2010-06-02 16:28 ` Scott Wood
2010-06-03 9:12 ` Martyn Welch
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