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=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,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 E2B07C43381 for ; Mon, 18 Mar 2019 16:24:11 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id B3C832087E for ; Mon, 18 Mar 2019 16:24:11 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="XGGI1ZYg" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B3C832087E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=mansr.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:Message-ID:In-Reply-To: Date:References:Subject:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=Gh+5BZ87oWfKXSrG0BF/p68FLPiGhr796p1NkdDeRnQ=; b=XGGI1ZYgvDPRrR lySss4QgQ3rZp/BmG8OyqVXB+45RqWHNCxZsn3bnstDn2zzfNRA+PAxGyUpyJiLk2hYoS33exRH5K p6pquNAkd7l8A1kGY6Du27OMI/neGqg2OUuHtCjVVcwaOmqEgm8+kXDA4t/GP+4TCB8egL1lJ7VXi tqZoJ8v2jTd5Pz+Om1ek+MekVliQyxUFXX4sGmUJnGqnDGddly/wLtMo/bo+W9bdJGpuyfuBS9sfo VvRQ/uYw2JSHoYMkDeD2UB2eWaYm4R3KMBsoLCcW2b8jmXyN5DgfZUUdEegstHIWspWqq4HSB71a9 5neP2QJo5nmJ9DOHmKiQ==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1h5v3X-0002L0-3Z; Mon, 18 Mar 2019 16:24:07 +0000 Received: from unicorn.mansr.com ([81.2.72.234]) by bombadil.infradead.org with esmtps (Exim 4.90_1 #2 (Red Hat Linux)) id 1h5v3T-0002GM-3z for linux-arm-kernel@lists.infradead.org; Mon, 18 Mar 2019 16:24:05 +0000 Received: by unicorn.mansr.com (Postfix, from userid 51770) id 405CA1562F; Mon, 18 Mar 2019 16:23:56 +0000 (GMT) From: =?iso-8859-1?Q?M=E5ns_Rullg=E5rd?= To: Maxime Ripard Subject: Re: [PATCH] drm/sun4i: hdmi: add support for ddc-i2c-bus property References: <20190311134713.25876-1-mans@mansr.com> <20190311154702.eslw5ccol44vxcmy@flea> <20190314154105.o6r7hzeuiyajxh7v@flea> <20190318155013.lge2x2cp5hvyz52f@flea> Date: Mon, 18 Mar 2019 16:23:56 +0000 In-Reply-To: <20190318155013.lge2x2cp5hvyz52f@flea> (Maxime Ripard's message of "Mon, 18 Mar 2019 16:50:13 +0100") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/25.3 (gnu/linux) MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190318_092403_475789_7E976DDC X-CRM114-Status: GOOD ( 23.75 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: David Airlie , Chen-Yu Tsai , linux-arm-kernel@lists.infradead.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org Maxime Ripard writes: > On Thu, Mar 14, 2019 at 04:09:13PM +0000, M=E5ns Rullg=E5rd wrote: >> Maxime Ripard writes: >> >> > On Mon, Mar 11, 2019 at 04:11:06PM +0000, M=E5ns Rullg=E5rd wrote: >> >> 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_con= nector *connector) >> >> >> struct edid *edid; >> >> >> int ret; >> >> >> >> >> >> - edid =3D drm_get_edid(connector, hdmi->i2c); >> >> >> + edid =3D 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_co= nnector *connector) >> >> >> return ret; >> >> >> } >> >> >> >> >> >> +static struct i2c_adapter *sun4i_hdmi_get_ddc(struct device *dev) >> >> >> +{ >> >> >> + struct device_node *phandle, *remote; >> >> >> + struct i2c_adapter *ddc; >> >> >> + >> >> >> + remote =3D of_graph_get_remote_node(dev->of_node, 1, -1); >> >> >> + if (!remote) >> >> >> + return ERR_PTR(-EINVAL); >> >> >> + >> >> >> + phandle =3D of_parse_phandle(remote, "ddc-i2c-bus", 0); >> >> >> + of_node_put(remote); >> >> >> + if (!phandle) >> >> >> + return NULL; >> >> >> + >> >> >> + ddc =3D 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 point= er. >> >> > >> >> >> +} >> >> >> + >> >> >> static const struct drm_connector_helper_funcs sun4i_hdmi_connect= or_helper_funcs =3D { >> >> >> .get_modes =3D 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 =3D 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 err= or >> >> 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. >> > >> > Indeed, I just got confused. I guess returning ENODEV in such a case, >> > and testing for that, would make things more obvious. >> >> There's also a case I hadn't thought of: property exists but isn't a >> valid phandle. What do you think is the correct action in that case? > > I think we would have that one covered. of_parse_phandle will return > !NULL, but then of_get_i2c_adapter_by_node will return NULL since we > wouldn't have an associated i2c adapter to the bogus phandle, and you > are checking for that already. of_parse_phandle() doesn't differentiate between a missing property and an existing non-phandle value. The following cases are possible with this patch: - ddc-i2c-bus points to valid i2c controller node: use this for ddc - no ddc-i2c-bus property: return NULL, use internal i2c - ddc-i2c-bus exists but isn't a phandle: likewise - ddc-i2c-bus points to a non-i2c-controller node: EPROBE_DEFER The last two cases obviously mean the devicetree is invalid, so perhaps it doesn't matter much what happens then. I don't think it's possible to distinguish between a well-formed phandle pointing to some bogus node and a good one where the i2c driver hasn't been probed yet. -- = M=E5ns Rullg=E5rd _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel