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From: Lucas Stach <dev-8ppwABl0HbeELgA04lAiVw@public.gmane.org>
To: Peter De Schrijver
	<pdeschrijver-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
Cc: Stephen Warren <swarren-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>,
	Joseph Lo <josephl-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>,
	Thierry Reding
	<thierry.reding-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>,
	"linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
	<linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
	"linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org"
	<linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org>,
	Mike Turquette
	<mturquette-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
Subject: Re: [PATCH 2/4] clk: tegra: add EMC clock driver
Date: Thu, 19 Dec 2013 12:43:28 +0100	[thread overview]
Message-ID: <1387453408.1712.3.camel@tellur> (raw)
In-Reply-To: <20131219100557.GE17188-Rysk9IDjsxmJz7etNGeUX8VPkgjIgRvpAL8bYrjMMd8@public.gmane.org>

Am Donnerstag, den 19.12.2013, 12:05 +0200 schrieb Peter De Schrijver:
[...]
> 
> > funny tricks like running from IRAM since we can't access SDRAM during
> > the clock change? If so, I'm not sure how having the EMC clock changing
> > code is going to help your case (2) anyway, since we'll presumably have
> > to code up a custom stub in assembly for the part of the code that runs
> > from IRAM...
> > 
> 
> There is no need for assembler or running from IRAM (at least from Tegra30
> onwards, I don't know about Tegra20).
> 
Tegra20 doesn't need any IRAM trickery, the sequence is just:
1. set up EMC shadow registers for new clock frequency
2. change EMC divider in CAR module

This was known working on Colibri T20 before the CCF change.

Regards,
Lucas

WARNING: multiple messages have this Message-ID (diff)
From: dev@lynxeye.de (Lucas Stach)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 2/4] clk: tegra: add EMC clock driver
Date: Thu, 19 Dec 2013 12:43:28 +0100	[thread overview]
Message-ID: <1387453408.1712.3.camel@tellur> (raw)
In-Reply-To: <20131219100557.GE17188@tbergstrom-lnx.Nvidia.com>

Am Donnerstag, den 19.12.2013, 12:05 +0200 schrieb Peter De Schrijver:
[...]
> 
> > funny tricks like running from IRAM since we can't access SDRAM during
> > the clock change? If so, I'm not sure how having the EMC clock changing
> > code is going to help your case (2) anyway, since we'll presumably have
> > to code up a custom stub in assembly for the part of the code that runs
> > from IRAM...
> > 
> 
> There is no need for assembler or running from IRAM (at least from Tegra30
> onwards, I don't know about Tegra20).
> 
Tegra20 doesn't need any IRAM trickery, the sequence is just:
1. set up EMC shadow registers for new clock frequency
2. change EMC divider in CAR module

This was known working on Colibri T20 before the CCF change.

Regards,
Lucas

  parent reply	other threads:[~2013-12-19 11:43 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-12-17  9:26 [PATCH 0/4] ARM: tegra: re-enable EMC scaling function for Tegra20 Joseph Lo
2013-12-17  9:26 ` Joseph Lo
     [not found] ` <1387272400-4689-1-git-send-email-josephl-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
2013-12-17  9:26   ` [PATCH 1/4] ARM: tegra: moving tegra_bct_strapping to tegra-soc.h for global visibility Joseph Lo
2013-12-17  9:26     ` Joseph Lo
     [not found]     ` <1387272400-4689-2-git-send-email-josephl-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
2013-12-17 22:53       ` Stephen Warren
2013-12-17 22:53         ` Stephen Warren
     [not found]         ` <52B0D5EF.5090703-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>
2013-12-18  8:20           ` Joseph Lo
2013-12-18  8:20             ` Joseph Lo
2013-12-17 22:58       ` Stephen Warren
2013-12-17 22:58         ` Stephen Warren
2013-12-17  9:26   ` [PATCH 2/4] clk: tegra: add EMC clock driver Joseph Lo
2013-12-17  9:26     ` Joseph Lo
     [not found]     ` <1387272400-4689-3-git-send-email-josephl-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
2013-12-17 22:58       ` Stephen Warren
2013-12-17 22:58         ` Stephen Warren
     [not found]         ` <52B0D6FA.2060101-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>
2013-12-18  9:42           ` Joseph Lo
2013-12-18  9:42             ` Joseph Lo
     [not found]             ` <1387359758.2576.38.camel-yx3yKKdKkHfc7b1ADBJPm0n48jw8i0AO@public.gmane.org>
2013-12-18 18:28               ` Stephen Warren
2013-12-18 18:28                 ` Stephen Warren
     [not found]                 ` <52B1E950.1040001-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>
2013-12-18 19:30                   ` Mike Turquette
2013-12-18 19:30                     ` Mike Turquette
2013-12-19  8:57                     ` Joseph Lo
2013-12-19  8:57                       ` Joseph Lo
2013-12-19  9:43                   ` Joseph Lo
2013-12-19  9:43                     ` Joseph Lo
     [not found]                     ` <1387446199.13057.26.camel-yx3yKKdKkHfc7b1ADBJPm0n48jw8i0AO@public.gmane.org>
2013-12-19 19:41                       ` Stephen Warren
2013-12-19 19:41                         ` Stephen Warren
2013-12-19 10:05                   ` Peter De Schrijver
2013-12-19 10:05                     ` Peter De Schrijver
     [not found]                     ` <20131219100557.GE17188-Rysk9IDjsxmJz7etNGeUX8VPkgjIgRvpAL8bYrjMMd8@public.gmane.org>
2013-12-19 11:43                       ` Lucas Stach [this message]
2013-12-19 11:43                         ` Lucas Stach
2013-12-19 11:46                         ` Peter De Schrijver
2013-12-19 11:46                           ` Peter De Schrijver
2013-12-19 19:44                       ` Stephen Warren
2013-12-19 19:44                         ` Stephen Warren
     [not found]                         ` <52B34CAB.5060705-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>
2013-12-20 11:34                           ` Peter De Schrijver
2013-12-20 11:34                             ` Peter De Schrijver
2013-12-17  9:26   ` [PATCH 3/4] memory: tegra20-emc: move out Tegra20 EMC driver from mach-tegra Joseph Lo
2013-12-17  9:26     ` Joseph Lo
2013-12-17  9:26   ` [PATCH 4/4] clk: tegra20: enable EMC clock driver Joseph Lo
2013-12-17  9:26     ` Joseph Lo
     [not found]     ` <1387272400-4689-5-git-send-email-josephl-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
2013-12-17 23:02       ` Stephen Warren
2013-12-17 23:02         ` Stephen Warren

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