From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dmitry Osipenko Subject: Re: [PATCH v2 2/2] clk: tegra20: Enable lock-status polling for PLLs Date: Wed, 17 Oct 2018 14:41:35 +0300 Message-ID: <2a011477-26cb-7e89-a468-54a84465f178@gmail.com> References: <20180830184210.5369-1-digetx@gmail.com> <20180830184210.5369-2-digetx@gmail.com> <20180831092948.GP1636@tbergstrom-lnx.Nvidia.com> <1539773948.6233.23.camel@toradex.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1539773948.6233.23.camel@toradex.com> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: Marcel Ziswiler , "pdeschrijver@nvidia.com" Cc: "linux-kernel@vger.kernel.org" , "jonathanh@nvidia.com" , "mturquette@baylibre.com" , "pgaikwad@nvidia.com" , "sboyd@kernel.org" , "thierry.reding@gmail.com" , "linux-clk@vger.kernel.org" , "linux-tegra@vger.kernel.org" List-Id: linux-tegra@vger.kernel.org On 10/17/18 1:59 PM, Marcel Ziswiler wrote: > On Fri, 2018-08-31 at 12:29 +0300, Peter De Schrijver wrote: >> On Thu, Aug 30, 2018 at 09:42:10PM +0300, Dmitry Osipenko wrote: >>> Currently all PLL's on Tegra20 use a hardcoded delay despite of >>> having >>> a lock-status bit. The lock-status polling was disabled ~7 years >>> ago >>> because PLLE was failing to lock and was a suspicion that other >>> PLLs >>> might be faulty too. Other PLLs are okay, hence enable the lock- >>> status >>> polling for them. This reduces delay of any operation that require >>> PLL >>> to lock. >>> >>> Signed-off-by: Dmitry Osipenko >>> --- >>> >>> Changelog: >>> >>> v2: Don't enable polling for PLLE as it known to not being >>> able to lock. >>> >> >> This isn't correct. The lock bit of PLLE can declare lock too early, >> but the >> PLL itself does lock. > > Is there an errata documenting this? As I could not really find any > mentioning of this anywhere at least up to the v11 from Dec 21, 2010 I > still have access to. > > BTW: It looks like also PLLA may not always lock properly with those > changes. Is there anything known about that as well? Here is what I get > on various Colibri T20 modules (while random other ones seem to work > fine): Could you please try to increase the timeout value?