From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.3 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A9938C4CECE for ; Wed, 18 Sep 2019 23:23:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 76B2E218AF for ; Wed, 18 Sep 2019 23:23:49 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="nShk7NWJ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387601AbfIRXXs (ORCPT ); Wed, 18 Sep 2019 19:23:48 -0400 Received: from perceval.ideasonboard.com ([213.167.242.64]:45044 "EHLO perceval.ideasonboard.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727305AbfIRXXs (ORCPT ); Wed, 18 Sep 2019 19:23:48 -0400 Received: from pendragon.ideasonboard.com (unknown [62.28.174.186]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 04BFA325; Thu, 19 Sep 2019 01:23:45 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1568849026; bh=CsWkpj58En/6J7/qAS77FlSWExqy9AKH1VdP6g61ZUg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=nShk7NWJOFYk49xtahOzsVjqt2Bh6+vJMFmregXx2A6waxNcOQ1h1LDIoWNkRJnqL wnB8rB4Kx7DOFqTt5Qc6BAGo+2Ik8tkL2ewO5KEbqD440/pUYc39WWKKU9tOvYfTnf +t+AmOew/rq3xgHRFYkwMaDO+/WxINYsc7XQz6qo= Date: Thu, 19 Sep 2019 02:23:36 +0300 From: Laurent Pinchart To: Kieran Bingham Cc: Jacopo Mondi , Jacopo Mondi , geert@linux-m68k.org, horms@verge.net.au, uli+renesas@fpond.eu, VenkataRajesh.Kalakodima@in.bosch.com, airlied@linux.ie, daniel@ffwll.ch, koji.matsuoka.xm@renesas.com, muroya@ksk.co.jp, Harsha.ManjulaMallikarjun@in.bosch.com, linux-renesas-soc@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v4 6/9] drm: rcar-du: crtc: Enable and disable CMMs Message-ID: <20190918232336.GB11474@pendragon.ideasonboard.com> References: <20190906135436.10622-1-jacopo+renesas@jmondi.org> <20190906135436.10622-7-jacopo+renesas@jmondi.org> <20190912080720.bn7bmu2o3gacrpf4@uno.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, On Thu, Sep 12, 2019 at 10:19:30AM +0100, Kieran Bingham wrote: > On 12/09/2019 09:07, Jacopo Mondi wrote: > > On Wed, Sep 11, 2019 at 07:40:27PM +0100, Kieran Bingham wrote: > >> On 06/09/2019 14:54, Jacopo Mondi wrote: > >>> Enable/disable the CMM associated with a CRTC at CRTC start and stop > >>> time and enable the CMM unit through the Display Extensional Functions > >>> register at group setup time. > >>> > >>> Reviewed-by: Ulrich Hecht > >>> Reviewed-by: Laurent Pinchart > >>> Signed-off-by: Jacopo Mondi > >>> --- > >>> drivers/gpu/drm/rcar-du/rcar_du_crtc.c | 7 +++++++ > >>> drivers/gpu/drm/rcar-du/rcar_du_group.c | 8 ++++++++ > >>> drivers/gpu/drm/rcar-du/rcar_du_regs.h | 5 +++++ > >>> 3 files changed, 20 insertions(+) > >>> > >>> diff --git a/drivers/gpu/drm/rcar-du/rcar_du_crtc.c b/drivers/gpu/drm/rcar-du/rcar_du_crtc.c > >>> index 23f1d6cc1719..3dac605c3a67 100644 > >>> --- a/drivers/gpu/drm/rcar-du/rcar_du_crtc.c > >>> +++ b/drivers/gpu/drm/rcar-du/rcar_du_crtc.c > >>> @@ -21,6 +21,7 @@ > >>> #include > >>> #include > >>> > >>> +#include "rcar_cmm.h" > >>> #include "rcar_du_crtc.h" > >>> #include "rcar_du_drv.h" > >>> #include "rcar_du_encoder.h" > >>> @@ -619,6 +620,9 @@ static void rcar_du_crtc_stop(struct rcar_du_crtc *rcrtc) > >>> if (rcar_du_has(rcrtc->dev, RCAR_DU_FEATURE_VSP1_SOURCE)) > >>> rcar_du_vsp_disable(rcrtc); > >>> > >>> + if (rcrtc->cmm) > >>> + rcar_cmm_disable(rcrtc->cmm); > >>> + > >>> /* > >>> * Select switch sync mode. This stops display operation and configures > >>> * the HSYNC and VSYNC signals as inputs. > >>> @@ -686,6 +690,9 @@ static void rcar_du_crtc_atomic_enable(struct drm_crtc *crtc, > >>> } > >>> > >>> rcar_du_crtc_start(rcrtc); > >>> + > >>> + if (rcrtc->cmm) > >>> + rcar_cmm_enable(rcrtc->cmm); > >>> } > >>> > >>> static void rcar_du_crtc_atomic_disable(struct drm_crtc *crtc, > >>> diff --git a/drivers/gpu/drm/rcar-du/rcar_du_group.c b/drivers/gpu/drm/rcar-du/rcar_du_group.c > >>> index 9eee47969e77..25d0fc125d7a 100644 > >>> --- a/drivers/gpu/drm/rcar-du/rcar_du_group.c > >>> +++ b/drivers/gpu/drm/rcar-du/rcar_du_group.c > >>> @@ -147,6 +147,14 @@ static void rcar_du_group_setup(struct rcar_du_group *rgrp) > >>> > >>> rcar_du_group_setup_pins(rgrp); > >>> > >>> + if (rcar_du_has(rcdu, RCAR_DU_FEATURE_CMM)) { > >>> + u32 defr7 = DEFR7_CODE > >>> + | (rgrp->cmms_mask & BIT(1) ? DEFR7_CMME1 : 0) > >>> + | (rgrp->cmms_mask & BIT(0) ? DEFR7_CMME0 : 0); > >>> + > >>> + rcar_du_group_write(rgrp, DEFR7, defr7); > >>> + } > >>> + > >> > >> What's the effect here on platforms with a CMM, but with > >> CONFIG_DRM_RCAR_CMM unset? > >> > >> Will this incorrectly configure the DU ? > >> > >> Will it stall the display if the DU tries to interact with another > >> module which is not enabled? > > > > I recall I tested that (that's why I had to add stubs for CMM > > functions, as I had linkage errors otherwise) and thing seems to be > > fine as the CMM configuration/enblement resolve to an empty function. > > Yes, I see the stubs to allow for linkage, but it's the hardware I'm > concerned about. If it passes the tests and doesn't break then that's > probably ok ... but I'm really weary that we're enabling a hardware > pipeline with a disabled component in the middle. > > > Would you prefer to have this guarded by an #if IS_ENABLED() ? > > I don't think we need a compile time conditional, but I'd say it > probably needs to be more about whether the CMM has actually probed or not > > Aha, and I see that in rcar_du_cmm_init() we already do a > call to rcar_cmm_init(), which if fails will leave rcdu->cmms[i] as > NULL. So that's catered for, which results in the rgrp->cmms_mask being > correctly representative of whether there is a CMM connected or not. Doesn't this result in probe failure ? > ... so I think that means the ... > "if (rcar_du_has(rcdu, RCAR_DU_FEATURE_CMM))" is somewhat redundant: > > > This could be: > > if (rgrp->cmms_mask) { > u32 defr7 = DEFR7_CODE > | (rgrp->cmms_mask & BIT(1) ? DEFR7_CMME1 : 0) > | (rgrp->cmms_mask & BIT(0) ? DEFR7_CMME0 : 0); > > rcar_du_group_write(rgrp, DEFR7, defr7); > > Or in fact, if we don't mind writing 0 to DEFR7 when there is no CMM > (which is safe by the looks of things as DEFR7 is available on all > platforms), then we can even remove the outer conditional, and leave > this all up to the ternary operators to write the correct value to the > defr7. > > Phew ... net result - your current code *is* safe with the > CONFIG_DRM_RCAR_CMM option disabled. I'll leave it up to you if you want > to simplify the code here and remove the RCAR_DU_FEATURE_CMM. > > As this RCAR_DU_FEATURE_CMM flag is only checked here, removing it would > however simplify all of the rcar_du_device_info structures. > > So - with or without the _FEATURE_CMM" simplification, this patch looks > functional and safe so: > > > Reviewed-by: Kieran Bingham > > >>> if (rcdu->info->gen >= 2) { > >>> rcar_du_group_setup_defr8(rgrp); > >>> rcar_du_group_setup_didsr(rgrp); > >>> diff --git a/drivers/gpu/drm/rcar-du/rcar_du_regs.h b/drivers/gpu/drm/rcar-du/rcar_du_regs.h > >>> index bc87f080b170..fb9964949368 100644 > >>> --- a/drivers/gpu/drm/rcar-du/rcar_du_regs.h > >>> +++ b/drivers/gpu/drm/rcar-du/rcar_du_regs.h > >>> @@ -197,6 +197,11 @@ > >>> #define DEFR6_MLOS1 (1 << 2) > >>> #define DEFR6_DEFAULT (DEFR6_CODE | DEFR6_TCNE1) > >>> > >>> +#define DEFR7 0x000ec > >>> +#define DEFR7_CODE (0x7779 << 16) > >>> +#define DEFR7_CMME1 BIT(6) > >>> +#define DEFR7_CMME0 BIT(4) > >>> + > >>> /* ----------------------------------------------------------------------------- > >>> * R8A7790-only Control Registers > >>> */ -- Regards, Laurent Pinchart