From: christophe leroy <christophe.leroy@c-s•fr>
To: Scott Wood <scottwood@freescale•com>
Cc: Marcelo Tosatti <marcelo@kvack•org>,
linux-kernel@vger•kernel.org, linux-spi@vger•kernel.org,
Mark Brown <broonie@kernel•org>,
Paul Mackerras <paulus@samba•org>,
linuxppc-dev@lists•ozlabs.org
Subject: Re: [PATCH 2/2] spi: fsl-spi: Allow dynamic allocation of CPM1 parameter RAM
Date: Sat, 04 Oct 2014 12:15:29 +0200 [thread overview]
Message-ID: <542FC8C1.1000707@c-s.fr> (raw)
In-Reply-To: <1412367858.13320.432.camel@snotra.buserror.net>
Le 03/10/2014 22:24, Scott Wood a écrit :
> On Fri, 2014-10-03 at 22:15 +0200, christophe leroy wrote:
>> Le 03/10/2014 16:44, Mark Brown a écrit :
>>> On Fri, Oct 03, 2014 at 02:56:09PM +0200, Christophe Leroy wrote:
>>>
>>>> +config CPM1_RELOCSPI
>>>> + bool "Dynamic SPI relocation"
>>>> + default n
>>>> + help
>>>> + On recent MPC8xx (at least MPC866 and MPC885) SPI can be relocated
>>>> + without micropatch. This activates relocation to a dynamically
>>>> + allocated area in the CPM Dual port RAM.
>>>> + When combined with SPI relocation patch (for older MPC8xx) it avoids
>>>> + the "loss" of additional Dual port RAM space just above the patch,
>>>> + which might be needed for example when using the CPM QMC.
>>> Something like this shouldn't be a compile time option. Either it
>>> should be unconditional or it should be triggered in some system
>>> specific manner (from DT, from knowing about other users or similar).
>> Can't be unconditional as older versions of mpc8xx (eg MPC860) don't
>> support relocation without a micropatch.
>> I have therefore submitted a v2 based on a DTS compatible property.
> So the device tree change is about whether relocation is supported, not
> whether it is required?
Indeed no, my intension is to say that relocation is requested. Do you
mean that it should then not use a compatible ?
> Is this specific to SPI or does the relocation
> mechanism work for other things?
Relocation is the same for I2C.
It is also possible to relocate SMC1 and SMC2 parameter RAM but only
with a micropatch.
Today, the kernel only implements relocation of SMC1, and it relocates
it at a fixed address just after SMC2 at offset 0x1FC0.
>
> How about checking for the existing specific-SoC compatibles?
What do you mean ?
Christophe
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next prev parent reply other threads:[~2014-10-04 10:15 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-03 12:56 [PATCH 2/2] spi: fsl-spi: Allow dynamic allocation of CPM1 parameter RAM Christophe Leroy
2014-10-03 14:44 ` Mark Brown
2014-10-03 20:15 ` christophe leroy
2014-10-03 20:24 ` Scott Wood
2014-10-04 10:15 ` christophe leroy [this message]
2014-10-07 0:19 ` Scott Wood
2014-10-08 16:46 ` leroy christophe
2014-10-08 18:45 ` Scott Wood
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