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 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 697F3C43381 for ; Mon, 11 Mar 2019 16:11:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 38531206BA for ; Mon, 11 Mar 2019 16:11:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727514AbfCKQLI convert rfc822-to-8bit (ORCPT ); Mon, 11 Mar 2019 12:11:08 -0400 Received: from unicorn.mansr.com ([81.2.72.234]:34224 "EHLO unicorn.mansr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726625AbfCKQLH (ORCPT ); Mon, 11 Mar 2019 12:11:07 -0400 Received: by unicorn.mansr.com (Postfix, from userid 51770) id 3983314CEA; Mon, 11 Mar 2019 16:11:06 +0000 (GMT) From: =?iso-8859-1?Q?M=E5ns_Rullg=E5rd?= To: Maxime Ripard Cc: David Airlie , Chen-Yu Tsai , dri-devel@lists.freedesktop.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] drm/sun4i: hdmi: add support for ddc-i2c-bus property References: <20190311134713.25876-1-mans@mansr.com> <20190311154702.eslw5ccol44vxcmy@flea> Date: Mon, 11 Mar 2019 16:11:06 +0000 In-Reply-To: <20190311154702.eslw5ccol44vxcmy@flea> (Maxime Ripard's message of "Mon, 11 Mar 2019 16:47:02 +0100") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/25.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Maxime Ripard writes: > Hi! > > On Mon, Mar 11, 2019 at 01:47:13PM +0000, Mans Rullgard wrote: >> Sometimes it is desirabled to use a separate i2c controller for ddc >> access. This adds support for the ddc-i2c-bus property of the >> hdmi-connector node, using the specified controller if provided. >> >> Signed-off-by: Mans Rullgard >> --- >> drivers/gpu/drm/sun4i/sun4i_hdmi.h | 1 + >> drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c | 37 +++++++++++++++++++++++--- >> 2 files changed, 35 insertions(+), 3 deletions(-) >> >> diff --git a/drivers/gpu/drm/sun4i/sun4i_hdmi.h b/drivers/gpu/drm/sun4i/sun4i_hdmi.h >> index b685ee11623d..b08c4453d47c 100644 >> --- a/drivers/gpu/drm/sun4i/sun4i_hdmi.h >> +++ b/drivers/gpu/drm/sun4i/sun4i_hdmi.h >> @@ -269,6 +269,7 @@ struct sun4i_hdmi { >> struct clk *tmds_clk; >> >> struct i2c_adapter *i2c; >> + struct i2c_adapter *ddc_i2c; >> >> /* Regmap fields for I2C adapter */ >> struct regmap_field *field_ddc_en; >> diff --git a/drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c b/drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c >> index 061d2e0d9011..5b2fac79f5d6 100644 >> --- a/drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c >> +++ b/drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c >> @@ -212,7 +212,7 @@ static int sun4i_hdmi_get_modes(struct drm_connector *connector) >> struct edid *edid; >> int ret; >> >> - edid = drm_get_edid(connector, hdmi->i2c); >> + edid = drm_get_edid(connector, hdmi->ddc_i2c ?: hdmi->i2c); > > You can't test whether ddc_i2c is NULL or not... > >> if (!edid) >> return 0; >> >> @@ -228,6 +228,28 @@ static int sun4i_hdmi_get_modes(struct drm_connector *connector) >> return ret; >> } >> >> +static struct i2c_adapter *sun4i_hdmi_get_ddc(struct device *dev) >> +{ >> + struct device_node *phandle, *remote; >> + struct i2c_adapter *ddc; >> + >> + remote = of_graph_get_remote_node(dev->of_node, 1, -1); >> + if (!remote) >> + return ERR_PTR(-EINVAL); >> + >> + phandle = of_parse_phandle(remote, "ddc-i2c-bus", 0); >> + of_node_put(remote); >> + if (!phandle) >> + return NULL; >> + >> + ddc = of_get_i2c_adapter_by_node(phandle); >> + of_node_put(phandle); >> + if (!ddc) >> + return ERR_PTR(-EPROBE_DEFER); >> + >> + return ddc; > > ... Since even in (most) error cases you're returning a !NULL pointer. > >> +} >> + >> static const struct drm_connector_helper_funcs sun4i_hdmi_connector_helper_funcs = { >> .get_modes = sun4i_hdmi_get_modes, >> }; >> @@ -575,6 +597,12 @@ static int sun4i_hdmi_bind(struct device *dev, struct device *master, >> goto err_disable_mod_clk; >> } >> >> + hdmi->ddc_i2c = sun4i_hdmi_get_ddc(dev); >> + if (IS_ERR(hdmi->ddc_i2c)) { ... which is checked here. The property is optional, so the idea was to return null in that case and use the built-in controller. If the property exists but some error occurs, we want to abort rather than proceed with the fallback which almost certainly won't work. Maybe I got something wrong in that logic. -- Måns Rullgård