Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752570AbbDAWbL (ORCPT ); Wed, 1 Apr 2015 18:31:11 -0400 Received: from bhuna.collabora.co.uk ([93.93.135.160]:46449 "EHLO bhuna.collabora.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752463AbbDAWbJ (ORCPT ); Wed, 1 Apr 2015 18:31:09 -0400 Message-ID: <551C71A5.1070903@collabora.co.uk> Date: Thu, 02 Apr 2015 00:31:01 +0200 From: Javier Martinez Canillas User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Icedove/31.2.0 MIME-Version: 1.0 To: Sylwester Nawrocki CC: Abhilash Kesavan , Tomasz Figa , Stephen Boyd , Mike Turquette , Kukjin Kim , Olof Johansson , Doug Anderson , Krzysztof Kozlowski , Kevin Hilman , Tyler Baker , Chanwoo Choi , linux-arm-kernel , "linux-samsung-soc@vger.kernel.org" , linux-kernel Subject: Re: [RFC PATCH v3 2/2] clk: exynos5420: Make sure MDMA0 clock is enabled during suspend References: <1427730803-28635-1-git-send-email-javier.martinez@collabora.co.uk> <1427730803-28635-3-git-send-email-javier.martinez@collabora.co.uk> <551976F1.1000605@collabora.co.uk> <551AFCCE.4050404@collabora.co.uk> <551BD07E.2090506@samsung.com> <551BDA0A.7010704@collabora.co.uk> <551C2B6D.4010001@samsung.com> In-Reply-To: <551C2B6D.4010001@samsung.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3903 Lines: 87 Hello Sylwester, On 04/01/2015 07:31 PM, Sylwester Nawrocki wrote: > On 01/04/15 13:44, Javier Martinez Canillas wrote: >> On 04/01/2015 01:03 PM, Sylwester Nawrocki wrote: >>> It's not clear what subsystems affect state of the CG_STATUSx registers, it >>> would be good if we could get more information on that. They are in the PMU >>> block and are related to LPI (Low Power Interface handshaking), but what >>> subsystems/peripheral blocks exactly are associated with them it's not clear >>> from the documentation. >> >> Yes, I've been looking at the docs again and found out a couple of things: >> >> * Each GC_STATUSx register bit is associated with an IP hw block >> * Some LPI_MASKx registers maps exactly with the GC_STATUSx (i.e: 0 and 1) >> and others maps only partially (i.e: LPI_MASK2 and GC_STATUS2) > > The CG_STATUSx and LPI_MASKx bits meaning is not matching according to > documentation I have. I guess you've got something newer than REV0.00? > My Exynos5420 UM is Revision 1.00 dated February 2014 and GC_STATUS0 bits maps LPI_MASK0 with the exception of bit 16 (NR3D) that is not mentioned in GC_STATUS0, there is a hole between 15 (DIS) and 17 (FIMC_SCALERP). GC_STATUS1 maps exactly with LPI_MASK1 and GC_STATUS2 and LPI_MASK2 have the same bits from 0 to 5 and then differ from there. >> So it is related to LPI as you said and both LPI_MASKx and GC_STATUSx are >> part of the PMU register address space. >> >> In the particular case of aclk266_g2d, the doc says that the clock can only >> be gated when CG_STATUS0[20] and CG_STATUS0[21] are 0. These are associated >> with the SSS and SSS_SLIM respectively which AFAIU are crypto h/w modules. > > In my Exynos5420 UM ACLK_266_G2D is associated with CG_STATUS0 register > bits 22, 21, which in turn correspond to NR3D and DIS IP blocks, i.e. > the camera subsystem. Such a dependency would be rather surprising. > Sorry, it was a typo error and I actually meant CG_STATUS0 21 and 22 but these correspond in the documentation I've to 21 (SSS) and 22 (SSS_SLIM). As I mentioned before, DIS correspond to CG_STATUS0 15 and NR3D doesn't have a corresponding bit in CG_STATUS0. But I don't know if that is an error in the doc I've since is suspicious that is the only difference between LPI_MASK0 and CG_STATUS0. >>> I think it's essential to understand what triggers changes in CG_STATUSx >>> registers, before we start checking their value in the clock driver. >>> >> >> Indeed, we should really understand what the status on these registers >> means. Also is not clear from the docs how much time should be waited, >> how long until giving up, etc. > > Exactly, I checked some kernels from http://opensource.samsung.com > (e.g. SM-N900_JB_Opensource.zip) for CG_STATUSx, but I didn't find anything > related to these registers yet, except the address macro definitions > and debug traces in the power domains driver. > Yes, I also looked in the ChromiumOS v3.8 kernel but didn't find anything. >>> Also it might be that there are indeed some clocks which must stay enabled >>> over suspend/resume cycle, then the approach with enabling/disabling clocks >>> in the clock driver might not be such a hack as it looks at first sight. >>> >> >> Having a clock driver to both a provider and consumer feels hacky to me as >> well but I didn't find a better way to solve this issue... another option >> is to have this workaround to solve the S2R issue while we figure out what >> the the state in the CG_STATUSx really mean. > > Let's try to diagnose the issue best we can, then we would choose the most > accurate bug fix. > Sounds good to me. Best regards, Javier -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/