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Mon, 22 Nov 2021 09:04:59 -0500 (EST) Date: Mon, 22 Nov 2021 15:04:57 +0100 From: Maxime Ripard To: Jagan Teki Cc: Chen-Yu Tsai , Laurent Pinchart , Neil Armstrong , Robert Foss , Sam Ravnborg , dri-devel@lists.freedesktop.org, linux-arm-kernel@lists.infradead.org, linux-sunxi@googlegroups.com, linux-amarula@amarulasolutions.com Subject: Re: [PATCH v5 3/7] drm: sun4i: dsi: Convert to bridge driver Message-ID: <20211122140457.jm7cwpp2h3fkf2nd@gilmour> References: <20211122065223.88059-1-jagan@amarulasolutions.com> <20211122065223.88059-4-jagan@amarulasolutions.com> <20211122100712.dls4eqsu6o5gcc5k@gilmour> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20211122_060501_456343_DB55C0E8 X-CRM114-Status: GOOD ( 45.68 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, Nov 22, 2021 at 07:18:13PM +0530, Jagan Teki wrote: > Hi Maxime, > > On Mon, Nov 22, 2021 at 3:37 PM Maxime Ripard wrote: > > > > On Mon, Nov 22, 2021 at 12:22:19PM +0530, Jagan Teki wrote: > > > Some display panels would come up with a non-DSI output, those > > > can have an option to connect the DSI host by means of interface > > > bridge converter. > > > > > > This DSI to non-DSI interface bridge converter would requires > > > DSI Host to handle drm bridge functionalities in order to DSI > > > Host to Interface bridge. > > > > In order to do this you would need to use the DRM bridge API... > > Sorry, which bridge API do you mean? Any variant of of_drm_find_bridge, and drm_bridge_attach. Just like we're doing in sun4i_rgb.c > > > This patch convert the existing to a drm bridge driver with a > > > built-in encoder support for compatibility with existing > > > component drivers. > > > > ... but changing the encoder driver to a bridge is completely > > unnecessary to do so. Why did you need to make that change? > > Idea of this series is to convert the driver to bridge and use the > latest bridge function from the v1 series. Ok, but it's not at all what you mention in your commit log? You don't need any of that in order to support a bridge downstream. > > > > > Signed-off-by: Jagan Teki > > > > > > --- > > > Changes for v5: > > > - add atomic APIs > > > - find host and device variant DSI devices. > > > Changes for v4, v3: > > > - none > > > > > > drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c | 112 ++++++++++++++++++++----- > > > drivers/gpu/drm/sun4i/sun6i_mipi_dsi.h | 7 ++ > > > 2 files changed, 96 insertions(+), 23 deletions(-) > > > > > > diff --git a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c > > > index 43d9c9e5198d..a6a272b55f77 100644 > > > --- a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c > > > +++ b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c > > > @@ -21,6 +21,7 @@ > > > > > > #include > > > #include > > > +#include > > > #include > > > #include > > > #include > > > @@ -713,10 +714,11 @@ static int sun6i_dsi_start(struct sun6i_dsi *dsi, > > > return 0; > > > } > > > > > > -static void sun6i_dsi_encoder_enable(struct drm_encoder *encoder) > > > +static void sun6i_dsi_bridge_atomic_enable(struct drm_bridge *bridge, > > > + struct drm_bridge_state *old_bridge_state) > > > { > > > - struct drm_display_mode *mode = &encoder->crtc->state->adjusted_mode; > > > - struct sun6i_dsi *dsi = encoder_to_sun6i_dsi(encoder); > > > + struct sun6i_dsi *dsi = bridge_to_sun6i_dsi(bridge); > > > + struct drm_display_mode *mode = &bridge->encoder->crtc->state->adjusted_mode; > > > struct mipi_dsi_device *device = dsi->device; > > > union phy_configure_opts opts = { }; > > > struct phy_configure_opts_mipi_dphy *cfg = &opts.mipi_dphy; > > > @@ -772,6 +774,9 @@ static void sun6i_dsi_encoder_enable(struct drm_encoder *encoder) > > > if (dsi->panel) > > > drm_panel_prepare(dsi->panel); > > > > > > + if (dsi->next_bridge) > > > + dsi->next_bridge->funcs->atomic_pre_enable(dsi->next_bridge, old_bridge_state); > > > + > > > > Please use the proper helpers. > > If we use bridge_functions we need to take atomic functions as > precedence as the next bridge functions might convert atomic calls. We've had this discussion over and over again, but this is something that needs to be documented and / or in your commit log. You must not deviate from the standard (and expected) behavior without any kind of justification. > > > > > /* > > > * FIXME: This should be moved after the switch to HS mode. > > > * > > > @@ -787,6 +792,9 @@ static void sun6i_dsi_encoder_enable(struct drm_encoder *encoder) > > > if (dsi->panel) > > > drm_panel_enable(dsi->panel); > > > > > > + if (dsi->next_bridge) > > > + dsi->next_bridge->funcs->atomic_enable(dsi->next_bridge, old_bridge_state); > > > + > > > > Ditto > > > > > sun6i_dsi_start(dsi, DSI_START_HSC); > > > > > > udelay(1000); > > > @@ -794,15 +802,19 @@ static void sun6i_dsi_encoder_enable(struct drm_encoder *encoder) > > > sun6i_dsi_start(dsi, DSI_START_HSD); > > > } > > > > > > -static void sun6i_dsi_encoder_disable(struct drm_encoder *encoder) > > > +static void sun6i_dsi_bridge_atomic_disable(struct drm_bridge *bridge, > > > + struct drm_bridge_state *old_bridge_state) > > > { > > > - struct sun6i_dsi *dsi = encoder_to_sun6i_dsi(encoder); > > > + struct sun6i_dsi *dsi = bridge_to_sun6i_dsi(bridge); > > > > > > DRM_DEBUG_DRIVER("Disabling DSI output\n"); > > > > > > if (dsi->panel) { > > > drm_panel_disable(dsi->panel); > > > drm_panel_unprepare(dsi->panel); > > > + } else if (dsi->next_bridge) { > > > + dsi->next_bridge->funcs->atomic_disable(dsi->next_bridge, old_bridge_state); > > > + dsi->next_bridge->funcs->atomic_post_disable(dsi->next_bridge, old_bridge_state); > > > > Ditto > > > > > } > > > > > > phy_power_off(dsi->dphy); > > > @@ -842,9 +854,25 @@ static const struct drm_connector_funcs sun6i_dsi_connector_funcs = { > > > .atomic_destroy_state = drm_atomic_helper_connector_destroy_state, > > > }; > > > > > > -static const struct drm_encoder_helper_funcs sun6i_dsi_enc_helper_funcs = { > > > - .disable = sun6i_dsi_encoder_disable, > > > - .enable = sun6i_dsi_encoder_enable, > > > +static int sun6i_dsi_bridge_attach(struct drm_bridge *bridge, > > > + enum drm_bridge_attach_flags flags) > > > +{ > > > + struct sun6i_dsi *dsi = bridge_to_sun6i_dsi(bridge); > > > + > > > + if (dsi->next_bridge) > > > + return drm_bridge_attach(bridge->encoder, dsi->next_bridge, > > > + NULL, 0); > > > + > > > + return 0; > > > +} > > > + > > > +static const struct drm_bridge_funcs sun6i_dsi_bridge_funcs = { > > > + .atomic_duplicate_state = drm_atomic_helper_bridge_duplicate_state, > > > + .atomic_destroy_state = drm_atomic_helper_bridge_destroy_state, > > > + .atomic_reset = drm_atomic_helper_bridge_reset, > > > + .atomic_enable = sun6i_dsi_bridge_atomic_enable, > > > + .atomic_disable = sun6i_dsi_bridge_atomic_disable, > > > + .attach = sun6i_dsi_bridge_attach, > > > }; > > > > > > static u32 sun6i_dsi_dcs_build_pkt_hdr(struct sun6i_dsi *dsi, > > > @@ -966,8 +994,6 @@ static int sun6i_dsi_bind(struct device *dev, struct device *master, > > > struct sun6i_dsi *dsi = dev_get_drvdata(dev); > > > int ret; > > > > > > - drm_encoder_helper_add(&dsi->encoder, > > > - &sun6i_dsi_enc_helper_funcs); > > > ret = drm_simple_encoder_init(drm, &dsi->encoder, > > > DRM_MODE_ENCODER_DSI); > > > if (ret) { > > > @@ -976,18 +1002,26 @@ static int sun6i_dsi_bind(struct device *dev, struct device *master, > > > } > > > dsi->encoder.possible_crtcs = BIT(0); > > > > > > - drm_connector_helper_add(&dsi->connector, > > > - &sun6i_dsi_connector_helper_funcs); > > > - ret = drm_connector_init(drm, &dsi->connector, > > > - &sun6i_dsi_connector_funcs, > > > - DRM_MODE_CONNECTOR_DSI); > > > + ret = drm_bridge_attach(&dsi->encoder, &dsi->bridge, NULL, 0); > > > if (ret) { > > > - dev_err(dsi->dev, > > > - "Couldn't initialise the DSI connector\n"); > > > + dev_err(dsi->dev, "Couldn't attach drm bridge\n"); > > > goto err_cleanup_connector; > > > } > > > > > > - drm_connector_attach_encoder(&dsi->connector, &dsi->encoder); > > > + if (dsi->panel) { > > > + drm_connector_helper_add(&dsi->connector, > > > + &sun6i_dsi_connector_helper_funcs); > > > + ret = drm_connector_init(drm, &dsi->connector, > > > + &sun6i_dsi_connector_funcs, > > > + DRM_MODE_CONNECTOR_DSI); > > > + if (ret) { > > > + dev_err(dsi->dev, > > > + "Couldn't initialise the DSI connector\n"); > > > + goto err_cleanup_connector; > > > + } > > > + > > > + drm_connector_attach_encoder(&dsi->connector, &dsi->encoder); > > > + } > > > > > > return 0; > > > > > > @@ -1013,16 +1047,46 @@ static int sun6i_dsi_attach(struct mipi_dsi_host *host, > > > struct mipi_dsi_device *device) > > > { > > > struct sun6i_dsi *dsi = host_to_sun6i_dsi(host); > > > - struct drm_panel *panel = of_drm_find_panel(device->dev.of_node); > > > + struct device_node *remote = device->dev.of_node; > > > int ret; > > > > > > - if (IS_ERR(panel)) > > > - return PTR_ERR(panel); > > > + if (!of_device_is_available(remote)) { > > > + /** > > > + * I2C interfaced DSI bridges will register DSI host on the > > > + * bridge drivers instead of conventional device. > > > + * > > > + * Those are probed via host of_node instead of device of_node. > > > + */ > > > > I have no idea what you mean here. Can you expand on what issue you've > > tried to solve here? > > I2C interface DSI bridges will register DSI host on the bridge > drivers. DSI bridges don't register a DSI host. > Those can be found using host->dev->of_node and cannot be find using > device->dev.of_node > > > > > > + remote = of_graph_get_remote_node(host->dev->of_node, 0, 0); > > > + if (!remote) > > > + return -ENODEV; > > > + } > > > + > > > + dsi->panel = of_drm_find_panel(remote); > > > + if (IS_ERR(dsi->panel)) { > > > + dsi->panel = NULL; > > > + > > > + dsi->next_bridge = of_drm_find_bridge(remote); > > > + if (IS_ERR(dsi->next_bridge)) { > > > + dev_err(dsi->dev, "failed to find bridge\n"); > > > + return PTR_ERR(dsi->next_bridge); > > > + } > > > + } else { > > > + dsi->next_bridge = NULL; > > > + } > > > + > > > + of_node_put(remote); > > > > Using devm_drm_of_get_bridge would greatly simplify the driver > > I'm aware of this and this would break the existing sunxi dsi binding, > we are not using ports based pipeline in dsi node. Of-course you have > pointed the same before, please check below > https://patchwork.kernel.org/project/dri-devel/patch/20210322140152.101709-2-jagan@amarulasolutions.com/ Then drm_of_find_panel_or_bridge needs to be adjusted to handle the DSI bindings and look for a panel or bridge not only through the OF graph, but also on the child nodes Maxime _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel 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 Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 998F8C433F5 for ; Mon, 22 Nov 2021 14:05:03 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 85F5589C84; 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Mon, 22 Nov 2021 09:04:59 -0500 (EST) Date: Mon, 22 Nov 2021 15:04:57 +0100 From: Maxime Ripard To: Jagan Teki Subject: Re: [PATCH v5 3/7] drm: sun4i: dsi: Convert to bridge driver Message-ID: <20211122140457.jm7cwpp2h3fkf2nd@gilmour> References: <20211122065223.88059-1-jagan@amarulasolutions.com> <20211122065223.88059-4-jagan@amarulasolutions.com> <20211122100712.dls4eqsu6o5gcc5k@gilmour> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable In-Reply-To: X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Neil Armstrong , Robert Foss , linux-sunxi@googlegroups.com, dri-devel@lists.freedesktop.org, Chen-Yu Tsai , Laurent Pinchart , Sam Ravnborg , linux-amarula@amarulasolutions.com, linux-arm-kernel@lists.infradead.org Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On Mon, Nov 22, 2021 at 07:18:13PM +0530, Jagan Teki wrote: > Hi Maxime, >=20 > On Mon, Nov 22, 2021 at 3:37 PM Maxime Ripard wrote: > > > > On Mon, Nov 22, 2021 at 12:22:19PM +0530, Jagan Teki wrote: > > > Some display panels would come up with a non-DSI output, those > > > can have an option to connect the DSI host by means of interface > > > bridge converter. > > > > > > This DSI to non-DSI interface bridge converter would requires > > > DSI Host to handle drm bridge functionalities in order to DSI > > > Host to Interface bridge. > > > > In order to do this you would need to use the DRM bridge API... >=20 > Sorry, which bridge API do you mean? Any variant of of_drm_find_bridge, and drm_bridge_attach. Just like we're doing in sun4i_rgb.c > > > This patch convert the existing to a drm bridge driver with a > > > built-in encoder support for compatibility with existing > > > component drivers. > > > > ... but changing the encoder driver to a bridge is completely > > unnecessary to do so. Why did you need to make that change? >=20 > Idea of this series is to convert the driver to bridge and use the > latest bridge function from the v1 series. Ok, but it's not at all what you mention in your commit log? You don't need any of that in order to support a bridge downstream. > > > > > Signed-off-by: Jagan Teki > > > > > > --- > > > Changes for v5: > > > - add atomic APIs > > > - find host and device variant DSI devices. > > > Changes for v4, v3: > > > - none > > > > > > drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c | 112 ++++++++++++++++++++---= -- > > > drivers/gpu/drm/sun4i/sun6i_mipi_dsi.h | 7 ++ > > > 2 files changed, 96 insertions(+), 23 deletions(-) > > > > > > diff --git a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c b/drivers/gpu/drm= /sun4i/sun6i_mipi_dsi.c > > > index 43d9c9e5198d..a6a272b55f77 100644 > > > --- a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c > > > +++ b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c > > > @@ -21,6 +21,7 @@ > > > > > > #include > > > #include > > > +#include > > > #include > > > #include > > > #include > > > @@ -713,10 +714,11 @@ static int sun6i_dsi_start(struct sun6i_dsi *ds= i, > > > return 0; > > > } > > > > > > -static void sun6i_dsi_encoder_enable(struct drm_encoder *encoder) > > > +static void sun6i_dsi_bridge_atomic_enable(struct drm_bridge *bridge, > > > + struct drm_bridge_state *old= _bridge_state) > > > { > > > - struct drm_display_mode *mode =3D &encoder->crtc->state->adjust= ed_mode; > > > - struct sun6i_dsi *dsi =3D encoder_to_sun6i_dsi(encoder); > > > + struct sun6i_dsi *dsi =3D bridge_to_sun6i_dsi(bridge); > > > + struct drm_display_mode *mode =3D &bridge->encoder->crtc->state= ->adjusted_mode; > > > struct mipi_dsi_device *device =3D dsi->device; > > > union phy_configure_opts opts =3D { }; > > > struct phy_configure_opts_mipi_dphy *cfg =3D &opts.mipi_dphy; > > > @@ -772,6 +774,9 @@ static void sun6i_dsi_encoder_enable(struct drm_e= ncoder *encoder) > > > if (dsi->panel) > > > drm_panel_prepare(dsi->panel); > > > > > > + if (dsi->next_bridge) > > > + dsi->next_bridge->funcs->atomic_pre_enable(dsi->next_br= idge, old_bridge_state); > > > + > > > > Please use the proper helpers. >=20 > If we use bridge_functions we need to take atomic functions as > precedence as the next bridge functions might convert atomic calls. We've had this discussion over and over again, but this is something that needs to be documented and / or in your commit log. You must not deviate from the standard (and expected) behavior without any kind of justification. > > > > > /* > > > * FIXME: This should be moved after the switch to HS mode. > > > * > > > @@ -787,6 +792,9 @@ static void sun6i_dsi_encoder_enable(struct drm_e= ncoder *encoder) > > > if (dsi->panel) > > > drm_panel_enable(dsi->panel); > > > > > > + if (dsi->next_bridge) > > > + dsi->next_bridge->funcs->atomic_enable(dsi->next_bridge= , old_bridge_state); > > > + > > > > Ditto > > > > > sun6i_dsi_start(dsi, DSI_START_HSC); > > > > > > udelay(1000); > > > @@ -794,15 +802,19 @@ static void sun6i_dsi_encoder_enable(struct drm= _encoder *encoder) > > > sun6i_dsi_start(dsi, DSI_START_HSD); > > > } > > > > > > -static void sun6i_dsi_encoder_disable(struct drm_encoder *encoder) > > > +static void sun6i_dsi_bridge_atomic_disable(struct drm_bridge *bridg= e, > > > + struct drm_bridge_state *ol= d_bridge_state) > > > { > > > - struct sun6i_dsi *dsi =3D encoder_to_sun6i_dsi(encoder); > > > + struct sun6i_dsi *dsi =3D bridge_to_sun6i_dsi(bridge); > > > > > > DRM_DEBUG_DRIVER("Disabling DSI output\n"); > > > > > > if (dsi->panel) { > > > drm_panel_disable(dsi->panel); > > > drm_panel_unprepare(dsi->panel); > > > + } else if (dsi->next_bridge) { > > > + dsi->next_bridge->funcs->atomic_disable(dsi->next_bridg= e, old_bridge_state); > > > + dsi->next_bridge->funcs->atomic_post_disable(dsi->next_= bridge, old_bridge_state); > > > > Ditto > > > > > } > > > > > > phy_power_off(dsi->dphy); > > > @@ -842,9 +854,25 @@ static const struct drm_connector_funcs sun6i_ds= i_connector_funcs =3D { > > > .atomic_destroy_state =3D drm_atomic_helper_connector_destroy= _state, > > > }; > > > > > > -static const struct drm_encoder_helper_funcs sun6i_dsi_enc_helper_fu= ncs =3D { > > > - .disable =3D sun6i_dsi_encoder_disable, > > > - .enable =3D sun6i_dsi_encoder_enable, > > > +static int sun6i_dsi_bridge_attach(struct drm_bridge *bridge, > > > + enum drm_bridge_attach_flags flags) > > > +{ > > > + struct sun6i_dsi *dsi =3D bridge_to_sun6i_dsi(bridge); > > > + > > > + if (dsi->next_bridge) > > > + return drm_bridge_attach(bridge->encoder, dsi->next_bri= dge, > > > + NULL, 0); > > > + > > > + return 0; > > > +} > > > + > > > +static const struct drm_bridge_funcs sun6i_dsi_bridge_funcs =3D { > > > + .atomic_duplicate_state =3D drm_atomic_helper_bridge_duplicate_= state, > > > + .atomic_destroy_state =3D drm_atomic_helper_bridge_destroy_st= ate, > > > + .atomic_reset =3D drm_atomic_helper_bridge_reset, > > > + .atomic_enable =3D sun6i_dsi_bridge_atomic_enable, > > > + .atomic_disable =3D sun6i_dsi_bridge_atomic_disable, > > > + .attach =3D sun6i_dsi_bridge_attach, > > > }; > > > > > > static u32 sun6i_dsi_dcs_build_pkt_hdr(struct sun6i_dsi *dsi, > > > @@ -966,8 +994,6 @@ static int sun6i_dsi_bind(struct device *dev, str= uct device *master, > > > struct sun6i_dsi *dsi =3D dev_get_drvdata(dev); > > > int ret; > > > > > > - drm_encoder_helper_add(&dsi->encoder, > > > - &sun6i_dsi_enc_helper_funcs); > > > ret =3D drm_simple_encoder_init(drm, &dsi->encoder, > > > DRM_MODE_ENCODER_DSI); > > > if (ret) { > > > @@ -976,18 +1002,26 @@ static int sun6i_dsi_bind(struct device *dev, = struct device *master, > > > } > > > dsi->encoder.possible_crtcs =3D BIT(0); > > > > > > - drm_connector_helper_add(&dsi->connector, > > > - &sun6i_dsi_connector_helper_funcs); > > > - ret =3D drm_connector_init(drm, &dsi->connector, > > > - &sun6i_dsi_connector_funcs, > > > - DRM_MODE_CONNECTOR_DSI); > > > + ret =3D drm_bridge_attach(&dsi->encoder, &dsi->bridge, NULL, 0); > > > if (ret) { > > > - dev_err(dsi->dev, > > > - "Couldn't initialise the DSI connector\n"); > > > + dev_err(dsi->dev, "Couldn't attach drm bridge\n"); > > > goto err_cleanup_connector; > > > } > > > > > > - drm_connector_attach_encoder(&dsi->connector, &dsi->encoder); > > > + if (dsi->panel) { > > > + drm_connector_helper_add(&dsi->connector, > > > + &sun6i_dsi_connector_helper_fu= ncs); > > > + ret =3D drm_connector_init(drm, &dsi->connector, > > > + &sun6i_dsi_connector_funcs, > > > + DRM_MODE_CONNECTOR_DSI); > > > + if (ret) { > > > + dev_err(dsi->dev, > > > + "Couldn't initialise the DSI connector\= n"); > > > + goto err_cleanup_connector; > > > + } > > > + > > > + drm_connector_attach_encoder(&dsi->connector, &dsi->enc= oder); > > > + } > > > > > > return 0; > > > > > > @@ -1013,16 +1047,46 @@ static int sun6i_dsi_attach(struct mipi_dsi_h= ost *host, > > > struct mipi_dsi_device *device) > > > { > > > struct sun6i_dsi *dsi =3D host_to_sun6i_dsi(host); > > > - struct drm_panel *panel =3D of_drm_find_panel(device->dev.of_no= de); > > > + struct device_node *remote =3D device->dev.of_node; > > > int ret; > > > > > > - if (IS_ERR(panel)) > > > - return PTR_ERR(panel); > > > + if (!of_device_is_available(remote)) { > > > + /** > > > + * I2C interfaced DSI bridges will register DSI host on= the > > > + * bridge drivers instead of conventional device. > > > + * > > > + * Those are probed via host of_node instead of device = of_node. > > > + */ > > > > I have no idea what you mean here. Can you expand on what issue you've > > tried to solve here? >=20 > I2C interface DSI bridges will register DSI host on the bridge > drivers. DSI bridges don't register a DSI host. > Those can be found using host->dev->of_node and cannot be find using > device->dev.of_node >=20 > > > > > + remote =3D of_graph_get_remote_node(host->dev->of_node,= 0, 0); > > > + if (!remote) > > > + return -ENODEV; > > > + } > > > + > > > + dsi->panel =3D of_drm_find_panel(remote); > > > + if (IS_ERR(dsi->panel)) { > > > + dsi->panel =3D NULL; > > > + > > > + dsi->next_bridge =3D of_drm_find_bridge(remote); > > > + if (IS_ERR(dsi->next_bridge)) { > > > + dev_err(dsi->dev, "failed to find bridge\n"); > > > + return PTR_ERR(dsi->next_bridge); > > > + } > > > + } else { > > > + dsi->next_bridge =3D NULL; > > > + } > > > + > > > + of_node_put(remote); > > > > Using devm_drm_of_get_bridge would greatly simplify the driver >=20 > I'm aware of this and this would break the existing sunxi dsi binding, > we are not using ports based pipeline in dsi node. Of-course you have > pointed the same before, please check below > https://patchwork.kernel.org/project/dri-devel/patch/20210322140152.10170= 9-2-jagan@amarulasolutions.com/ Then drm_of_find_panel_or_bridge needs to be adjusted to handle the DSI bindings and look for a panel or bridge not only through the OF graph, but also on the child nodes Maxime