From: Mikhail Zolotaryov <lebon@lebon.org.ua>
To: linuxppc-dev@ozlabs.org
Subject: Re: [PATCH] PowerPC 440EPx/GRx fix memory size calculation
Date: Tue, 10 Mar 2009 22:57:11 +0200 [thread overview]
Message-ID: <49B6D427.5050600@lebon.org.ua> (raw)
In-Reply-To: <20090310195013.GA27835@ru.mvista.com>
Valentine Barshak wrote:
> According to the AMCC 440EPX/GRX user manual,
> the Chip Select width is always fixed at 1 bit no matter
> what is actually read from register DDR_10.
Well, from my point of view original kernel code is correct in this part.
Adding one bit into memory address means multiplying memory size by 2
i.e. cs=2. The question is: is Chip Select bit used in memory address.
ChipSelect input of memory chip enables or disabled it, so if we have
only one BankSel installed/connected (DDR0_10[22:23] is 01 or 10)
there's no need to use Chip Select bit in an address. On the contrary,
if both BankSel lines are connected (DDR0_10[22:23] is 11), to let
memory controller know which memory rank to use, Chip Select bit is
added into memory address. (and yes, if DDR0_10[22:23] is 00 - no ranks
installed, memory size is 0, cs=0)
Original kernel code use exactly the same logic as I described above.
Please suggest if it's wrong.
next prev parent reply other threads:[~2009-03-10 20:56 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-03-09 16:21 [PATCH] powerpc 4xx: DDR0_14[REDUC] decoded incorrectly Mikhail Zolotaryov
2009-03-09 16:21 ` Mikhail Zolotaryov
2009-03-09 17:12 ` Josh Boyer
2009-03-09 17:12 ` Josh Boyer
2009-03-09 21:17 ` Mikhail Zolotaryov
2009-03-09 21:17 ` Mikhail Zolotaryov
2009-03-10 19:50 ` [PATCH] PowerPC 440EPx/GRx fix memory size calculation Valentine Barshak
2009-03-10 20:57 ` Mikhail Zolotaryov [this message]
2009-03-11 1:40 ` Valentine
2009-03-11 2:26 ` Benjamin Herrenschmidt
2009-03-11 8:24 ` Mikhail Zolotaryov
2009-03-11 8:29 ` Mikhail Zolotaryov
2009-03-11 10:37 ` Josh Boyer
2009-03-11 19:06 ` Valentine Barshak
2009-03-11 21:57 ` Josh Boyer
2009-03-11 22:08 ` Valentine
2009-03-11 23:07 ` Josh Boyer
2009-03-12 6:02 ` Stefan Roese
2009-03-12 7:32 ` Benjamin Herrenschmidt
2009-03-12 8:05 ` Stefan Roese
2009-03-12 8:12 ` Benjamin Herrenschmidt
2009-03-12 8:24 ` Stefan Roese
2009-03-12 8:45 ` Mikhail Zolotaryov
2009-03-12 10:45 ` Josh Boyer
2009-03-12 11:02 ` Stefan Roese
2009-03-13 23:01 ` Feng Kan
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