From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751302AbeEBU3g (ORCPT ); Wed, 2 May 2018 16:29:36 -0400 Received: from mail.bootlin.com ([62.4.15.54]:34520 "EHLO mail.bootlin.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750993AbeEBU3e (ORCPT ); Wed, 2 May 2018 16:29:34 -0400 Date: Wed, 2 May 2018 22:29:21 +0200 From: Boris Brezillon To: Eric Anholt Cc: dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] drm/vc4: Fix oops dereferencing DPI's connector since panel_bridge. Message-ID: <20180502222921.4399847a@bbrezillon> In-Reply-To: <20180309233256.1667-1-eric@anholt.net> References: <20180309233256.1667-1-eric@anholt.net> X-Mailer: Claws Mail 3.15.0-dirty (GTK+ 2.24.31; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 9 Mar 2018 15:32:56 -0800 Eric Anholt wrote: > In the cleanup, I didn't notice that we needed to dereference the > connector for the bus_format. Fix the regression by looking up the > first (and only) connector attached to us, and assume that its > bus_format is what we want. Some day it would be good to have that > part of display_info attached to the bridge, instead. > > Signed-off-by: Eric Anholt > Fixes: 7b1298e05310 ("drm/vc4: Switch DPI to using the panel-bridge helper.") > Cc: Boris Brezillon Reviewed-by: Boris Brezillon > --- > drivers/gpu/drm/vc4/vc4_dpi.c | 27 +++++++++++++++++++++++---- > 1 file changed, 23 insertions(+), 4 deletions(-) > > diff --git a/drivers/gpu/drm/vc4/vc4_dpi.c b/drivers/gpu/drm/vc4/vc4_dpi.c > index 72c9dbd81d7f..88783e143cc2 100644 > --- a/drivers/gpu/drm/vc4/vc4_dpi.c > +++ b/drivers/gpu/drm/vc4/vc4_dpi.c > @@ -96,7 +96,6 @@ struct vc4_dpi { > struct platform_device *pdev; > > struct drm_encoder *encoder; > - struct drm_connector *connector; > > void __iomem *regs; > > @@ -164,14 +163,31 @@ static void vc4_dpi_encoder_disable(struct drm_encoder *encoder) > > static void vc4_dpi_encoder_enable(struct drm_encoder *encoder) > { > + struct drm_device *dev = encoder->dev; > struct drm_display_mode *mode = &encoder->crtc->mode; > struct vc4_dpi_encoder *vc4_encoder = to_vc4_dpi_encoder(encoder); > struct vc4_dpi *dpi = vc4_encoder->dpi; > + struct drm_connector_list_iter conn_iter; > + struct drm_connector *connector = NULL, *connector_scan; > u32 dpi_c = DPI_ENABLE | DPI_OUTPUT_ENABLE_MODE; > int ret; > > - if (dpi->connector->display_info.num_bus_formats) { > - u32 bus_format = dpi->connector->display_info.bus_formats[0]; > + /* Look up the connector attached to DPI so we can get the > + * bus_format. Ideally the bridge would tell us the > + * bus_format we want, but it doesn't yet, so assume that it's > + * uniform throughout the bridge chain. > + */ > + drm_connector_list_iter_begin(dev, &conn_iter); > + drm_for_each_connector_iter(connector_scan, &conn_iter) { > + if (connector_scan->encoder == encoder) { > + connector = connector_scan; > + break; > + } > + } > + drm_connector_list_iter_end(&conn_iter); > + > + if (connector && connector->display_info.num_bus_formats) { > + u32 bus_format = connector->display_info.bus_formats[0]; > > switch (bus_format) { > case MEDIA_BUS_FMT_RGB888_1X24: > @@ -199,6 +215,9 @@ static void vc4_dpi_encoder_enable(struct drm_encoder *encoder) > DRM_ERROR("Unknown media bus format %d\n", bus_format); > break; > } > + } else { > + /* Default to 24bit if no connector found. */ > + dpi_c |= VC4_SET_FIELD(DPI_FORMAT_24BIT_888_RGB, DPI_FORMAT); > } > > if (mode->flags & DRM_MODE_FLAG_NHSYNC) > @@ -264,7 +283,7 @@ static int vc4_dpi_init_bridge(struct vc4_dpi *dpi) > return ret; > } > > - if (panel) > + if (panel) > bridge = drm_panel_bridge_add(panel, DRM_MODE_CONNECTOR_DPI); > > return drm_bridge_attach(dpi->encoder, bridge, NULL);