From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lucas Stach Subject: Re: [PATCH 2/4] clk: tegra: add EMC clock driver Date: Thu, 19 Dec 2013 12:43:28 +0100 Message-ID: <1387453408.1712.3.camel@tellur> References: <1387272400-4689-1-git-send-email-josephl@nvidia.com> <1387272400-4689-3-git-send-email-josephl@nvidia.com> <52B0D6FA.2060101@wwwdotorg.org> <1387359758.2576.38.camel@jlo-ubuntu-64.nvidia.com> <52B1E950.1040001@wwwdotorg.org> <20131219100557.GE17188@tbergstrom-lnx.Nvidia.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20131219100557.GE17188-Rysk9IDjsxmJz7etNGeUX8VPkgjIgRvpAL8bYrjMMd8@public.gmane.org> Sender: linux-tegra-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Peter De Schrijver Cc: Stephen Warren , Joseph Lo , Thierry Reding , "linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org" , Mike Turquette List-Id: linux-tegra@vger.kernel.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