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=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED 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 D0C3BC10F14 for ; Tue, 23 Apr 2019 10:26:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AA05C2175B for ; Tue, 23 Apr 2019 10:26:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727387AbfDWK0O (ORCPT ); Tue, 23 Apr 2019 06:26:14 -0400 Received: from gloria.sntech.de ([185.11.138.130]:60428 "EHLO gloria.sntech.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726150AbfDWK0O (ORCPT ); Tue, 23 Apr 2019 06:26:14 -0400 Received: from p57b772a1.dip0.t-ipconnect.de ([87.183.114.161] helo=phil.localnet) by gloria.sntech.de with esmtpsa (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1hIsck-0001oz-Sc; Tue, 23 Apr 2019 12:26:02 +0200 From: Heiko Stuebner To: Jonas Karlman Cc: "dri-devel@lists.freedesktop.org" , Archit Taneja , Andrzej Hajda , Laurent Pinchart , David Airlie , Daniel Vetter , Neil Armstrong , Sean Paul , Jernej Skrabec , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH] drm/bridge: dw-hdmi: fix SCDC configuration for ddc-i2c-bus Date: Tue, 23 Apr 2019 12:26:02 +0200 Message-ID: <2275367.P1g2IIHPGP@phil> In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Am Sonntag, 21. April 2019, 10:25:50 CEST schrieb Jonas Karlman: > When ddc-i2c-bus property is used, a NULL pointer dereference is reported: > > [ 31.041669] Unable to handle kernel NULL pointer dereference at virtual address 00000008 > [ 31.041671] pgd = 4d3c16f6 > [ 31.041673] [00000008] *pgd=00000000 > [ 31.041678] Internal error: Oops: 5 [#1] SMP ARM > > [ 31.041711] Hardware name: Rockchip (Device Tree) > [ 31.041718] PC is at i2c_transfer+0x8/0xe4 > [ 31.041721] LR is at drm_scdc_read+0x54/0x84 > [ 31.041723] pc : [] lr : [] psr: 280f0013 > [ 31.041725] sp : edffdad0 ip : 5ccb5511 fp : 00000058 > [ 31.041727] r10: 00000780 r9 : edf91608 r8 : c11b0f48 > [ 31.041728] r7 : 00000438 r6 : 00000000 r5 : 00000000 r4 : 00000000 > [ 31.041730] r3 : edffdae7 r2 : 00000002 r1 : edffdaec r0 : 00000000 > > [ 31.041908] [] (i2c_transfer) from [] (drm_scdc_read+0x54/0x84) > [ 31.041913] [] (drm_scdc_read) from [] (drm_scdc_set_scrambling+0x30/0xbc) > [ 31.041919] [] (drm_scdc_set_scrambling) from [] (dw_hdmi_update_power+0x1440/0x1610) > [ 31.041926] [] (dw_hdmi_update_power) from [] (dw_hdmi_bridge_enable+0x2c/0x70) > [ 31.041932] [] (dw_hdmi_bridge_enable) from [] (drm_bridge_enable+0x24/0x34) > [ 31.041938] [] (drm_bridge_enable) from [] (drm_atomic_helper_commit_modeset_enables+0x114/0x220) > [ 31.041943] [] (drm_atomic_helper_commit_modeset_enables) from [] (rockchip_atomic_helper_commit_tail_rpm+0x28/0x64) > > hdmi->i2c may not be set when ddc-i2c-bus property is used in device tree. > Fix this by using hdmi->ddc as the i2c adapter when calling drm_scdc_*(). > Also report that SCDC is not supported when there is no DDC bus. > > Fixes: 264fce6cc2c1 ("drm/bridge: dw-hdmi: Add SCDC and TMDS Scrambling support") > Signed-off-by: Jonas Karlman I've looked that up and yeah, hdmi->ddc seems the right thing to use as it points either to the external i2c or the internal one, so Reviewed-by: Heiko Stuebner > --- > drivers/gpu/drm/bridge/synopsys/dw-hdmi.c | 12 ++++++++---- > 1 file changed, 8 insertions(+), 4 deletions(-) > > diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c > index 7a47c65d8ecb..fd1c319a4ee0 100644 > --- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c > +++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c > @@ -1046,6 +1046,10 @@ static bool dw_hdmi_support_scdc(struct dw_hdmi *hdmi) > if (hdmi->version < 0x200a) > return false; > > + /* Disable if no DDC bus */ > + if (!hdmi->ddc) > + return false; > + > /* Disable if SCDC is not supported, or if an HF-VSDB block is absent */ > if (!display->hdmi.scdc.supported || > !display->hdmi.scdc.scrambling.supported) > @@ -1683,13 +1687,13 @@ static void hdmi_av_composer(struct dw_hdmi *hdmi, > * Source Devices compliant shall set the > * Source Version = 1. > */ > - drm_scdc_readb(&hdmi->i2c->adap, SCDC_SINK_VERSION, > + drm_scdc_readb(hdmi->ddc, SCDC_SINK_VERSION, > &bytes); > - drm_scdc_writeb(&hdmi->i2c->adap, SCDC_SOURCE_VERSION, > + drm_scdc_writeb(hdmi->ddc, SCDC_SOURCE_VERSION, > min_t(u8, bytes, SCDC_MIN_SOURCE_VERSION)); > > /* Enabled Scrambling in the Sink */ > - drm_scdc_set_scrambling(&hdmi->i2c->adap, 1); > + drm_scdc_set_scrambling(hdmi->ddc, 1); > > /* > * To activate the scrambler feature, you must ensure > @@ -1705,7 +1709,7 @@ static void hdmi_av_composer(struct dw_hdmi *hdmi, > hdmi_writeb(hdmi, 0, HDMI_FC_SCRAMBLER_CTRL); > hdmi_writeb(hdmi, (u8)~HDMI_MC_SWRSTZ_TMDSSWRST_REQ, > HDMI_MC_SWRSTZ); > - drm_scdc_set_scrambling(&hdmi->i2c->adap, 0); > + drm_scdc_set_scrambling(hdmi->ddc, 0); > } > } > > -- > 2.17.1 > >