From mboxrd@z Thu Jan 1 00:00:00 1970 From: Heiko =?ISO-8859-1?Q?St=FCbner?= Subject: Re: [PATCH 1/5] clk: rockchip: Turn on "aclk_dmac1" for suspend Date: Fri, 12 Apr 2019 12:06:45 +0200 Message-ID: <17495106.TRDjcDkMKC@diego> References: <20190411232157.55125-1-dianders@chromium.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7Bit Return-path: In-Reply-To: <20190411232157.55125-1-dianders@chromium.org> Sender: linux-kernel-owner@vger.kernel.org To: Douglas Anderson Cc: Elaine Zhang , dbasehore@chromium.org, amstan@chromium.org, linux-rockchip@lists.infradead.org, briannorris@chromium.org, mka@chromium.org, ryandcase@chromium.org, Chris Zhong , Michael Turquette , Stephen Boyd , linux-kernel@vger.kernel.org, linux-clk@vger.kernel.org, linux-arm-kernel@lists.infradead.org List-Id: linux-rockchip.vger.kernel.org Am Freitag, 12. April 2019, 01:21:53 CEST schrieb Douglas Anderson: > Experimentally it can be seen that going into deep sleep (specifically > setting PMU_CLR_DMA and PMU_CLR_BUS in RK3288_PMU_PWRMODE_CON1) > appears to fail unless "aclk_dmac1" is on. The failure is that the > system never signals that it made it into suspend on the GLOBAL_PWROFF > pin and it just hangs. > > NOTE that it's confirmed that it's the actual suspend that fails, not > one of the earlier calls to read/write registers. Specifically if you > comment out the "PMU_GLOBAL_INT_DISABLE" setting in > rk3288_slp_mode_set() and then comment out the "cpu_do_idle()" call in > rockchip_lpmode_enter() then you can exercise the whole suspend path > without any crashing. > > This is currently not a problem with suspend upstream because there is > no current way to exercise the deep suspend code. However, anyone > trying to make it work will run into this issue. > > This was not a problem on shipping rk3288-based Chromebooks because > those devices all ran on an old kernel based on 3.14. On that kernel > "aclk_dmac1" appears to be left on all the time. > > There are several ways to skin this problem. > > A) We could add "aclk_dmac1" to the list of critical clocks and that > apperas to work, but presumably that wastes power. > > B) We could keep a list of "struct clk" objects to enable at suspend > time in clk-rk3288.c and use the standard clock APIs. > > C) We could make the rk3288-pmu driver keep a list of clocks to enable > at suspend time. Presumably this would require a dts and bindings > change. > > D) We could just whack the clock on in the existing syscore suspend > function where we whack a bunch of other clocks. This is particularly > easy because we know for sure that the clock's only parent > ("aclk_cpu") is a critical clock so we don't need to do anything more > than ungate it. > > In this case I have chosen D) because it seemed like the least work, > but any of the other options would presumably also work fine. > > Signed-off-by: Douglas Anderson applied for 5.2 with Elaine's rb Thanks Heiko