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=ham 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 14930C3A5A6 for ; Thu, 19 Sep 2019 08:08:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C4104207FC for ; Thu, 19 Sep 2019 08:08:26 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="PrWRX992" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730958AbfISII0 (ORCPT ); Thu, 19 Sep 2019 04:08:26 -0400 Received: from perceval.ideasonboard.com ([213.167.242.64]:52238 "EHLO perceval.ideasonboard.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725320AbfISII0 (ORCPT ); Thu, 19 Sep 2019 04:08:26 -0400 Received: from [192.168.0.20] (cpc89242-aztw30-2-0-cust488.18-1.cable.virginm.net [86.31.129.233]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 80282325; Thu, 19 Sep 2019 10:08:21 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1568880502; bh=38ol2YTAkpGhHSgnR8PdDk46glvBAqIWmdxP0glkm6o=; h=Reply-To:Subject:To:Cc:References:From:Date:In-Reply-To:From; b=PrWRX992tvlwttYYUP3tMtAAb7oqiYUOU6JAcXOhTa+MtBERLcUe5Rh0y5nuj9YXc XYPbrbxvTBiyCjkmaNwb6/cpJ2kcXXzYa1Fh3YHMz14tc/i6oKoplKf73AX8z8HRj/ gr7Q5pbNO2EB30cAyGwz76tLFNEnZkZWSjZbxjbc= Reply-To: kieran.bingham+renesas@ideasonboard.com Subject: Re: [PATCH v4 6/9] drm: rcar-du: crtc: Enable and disable CMMs To: Laurent Pinchart 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 References: <20190906135436.10622-1-jacopo+renesas@jmondi.org> <20190906135436.10622-7-jacopo+renesas@jmondi.org> <20190912080720.bn7bmu2o3gacrpf4@uno.localdomain> <20190918232336.GB11474@pendragon.ideasonboard.com> From: Kieran Bingham Organization: Ideas on Board Message-ID: <96aded2c-f083-6e3d-c07d-f392f52a01b0@ideasonboard.com> Date: Thu, 19 Sep 2019 09:08:18 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20190918232336.GB11474@pendragon.ideasonboard.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-GB Content-Transfer-Encoding: 7bit Sender: linux-renesas-soc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-renesas-soc@vger.kernel.org Hi Laurent, / Jacopo On 19/09/2019 00:23, Laurent Pinchart wrote: > 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 ? I think I mis-spoke above, I didn't mean "if rcar_cmm_init() fails" I meant "if rcar_du_cmm_init() determines there are no connected CMM's or if they are disabled." If rcar_cmm_init() returns a failure, then yes we will fail to probe. But I think it's up to rcar_du_cmm_init() to determine if the CMM exists or not (or is enabled) and if that's not a failure case then it should not prevent the probing of the DU. In fact, I've now seen that if CONFIG_DRM_RCAR_CMM is not enabled, rcar_cmm_init() returns 0, and I think in fact it should return -ENODEV, with an exception on that return value in rcar_du_cmm_init() so that the DU continues with no CMM attached there. > >> ... 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 >>>>> */ >