From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ben Dooks Subject: Re: [PATCH 2/8] clk: tegra: host1x has fractional divider Date: Mon, 23 Jul 2018 12:32:08 +0100 Message-ID: <0e52ce60b6d0aed73ca171352a56d3e7@codethink.co.uk> References: <20180720134532.13148-1-ben.dooks@codethink.co.uk> <20180720134532.13148-3-ben.dooks@codethink.co.uk> <20180723085010.GK1636@tbergstrom-lnx.Nvidia.com> <7df28a76490315402d28ad7de43dc0db@codethink.co.uk> <20180723111216.GM1636@tbergstrom-lnx.Nvidia.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20180723111216.GM1636@tbergstrom-lnx.Nvidia.com> Sender: linux-kernel-owner@vger.kernel.org To: Peter De Schrijver Cc: linux-clk@vger.kernel.org, linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org, pgaikwad@nvidia.com, jonathanh@nvidia.co, thierry.reding@gmail.com, linux-kernel@lists.codethink.co.uk List-Id: linux-tegra@vger.kernel.org On 2018-07-23 12:12, Peter De Schrijver wrote: > On Mon, Jul 23, 2018 at 10:32:58AM +0100, Ben Dooks wrote: >> >> >> On 2018-07-23 09:50, Peter De Schrijver wrote: >> >On Fri, Jul 20, 2018 at 02:45:26PM +0100, Ben Dooks wrote: >> >>The host1x clock according to both tegra2 and tegra3 manuals is >> >>an 8bit divider with lsb being fractional. This is running into >> >>an issue where the host1x is being set on a tegra20a system to >> >>266.4MHz but ends up at 222MHz instead. >> >> >> > >> >The fact the hw has a fractional divider, does not mean we're >> >allowed to use >> >it. Due to the non 50% duty cycle of fractional divided clocks, >> >they are not >> >allowed for certain peripherals. Do you have information >> >indicating this is >> >ok for the host1x clock? >> >> Only that's what was setup for the systems we're using. >> We couldn't match the 2.6 working system without these changes. >> > > On Tegra20 or Tegra30? I'll check tomorrow when I have access to all the hw involved. -- Ben