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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id CB552EB64D9 for ; Mon, 10 Jul 2023 07:38:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231230AbjGJHim (ORCPT ); Mon, 10 Jul 2023 03:38:42 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43312 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229834AbjGJHii (ORCPT ); Mon, 10 Jul 2023 03:38:38 -0400 Received: from madras.collabora.co.uk (madras.collabora.co.uk [IPv6:2a00:1098:0:82:1000:25:2eeb:e5ab]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C5D0F95 for ; Mon, 10 Jul 2023 00:38:36 -0700 (PDT) Received: from [192.168.1.100] (2-237-20-237.ip236.fastwebnet.it [2.237.20.237]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: kholk11) by madras.collabora.co.uk (Postfix) with ESMTPSA id B81236606FF3; Mon, 10 Jul 2023 08:38:34 +0100 (BST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1688974715; bh=LOXc+6Sqq2SjuM4ZCBO1k8rnrrk3ScMPXrSUxS0CCuE=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=iNE1sJ53UJG7JThYzk3vZyGbX3LodamTt5AcFLXPDLZtowxiXEgaeH4JdralBhJPp XugpSEzAqLSOrwg3ORcljgb8vJIk90v8Pc7pny3Z0E6w55h+DHac3pDQbTh70+JZ5f si2VcCK0bzBONTIAsWq2tN3LQPXdQ+6bRbxfjIZIpMHBhMTYE9XoTwqJ5utxJsw0v2 7E8FwkkufVJatjHiJnJ7F8dILMLB8aw4NA7N70ryufi4hprpNePY9XT3k1Kzc8ynmr 7aI38MKT9IwbuZnla3AwTW5IIK1+OboP8oUG6XXSSX8NvjFdlCzSm3413bLNWRwo7x zuJ6z1l/ljQEQ== Message-ID: Date: Mon, 10 Jul 2023 09:38:31 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.12.0 Subject: Re: [PATCH v4 0/9] MediaTek DisplayPort: support eDP and aux-bus To: Chen-Yu Tsai Cc: chunkuang.hu@kernel.org, p.zabel@pengutronix.de, airlied@gmail.com, daniel@ffwll.ch, matthias.bgg@gmail.com, dri-devel@lists.freedesktop.org, linux-mediatek@lists.infradead.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kernel@collabora.com, nfraprado@collabora.com References: <20230706123025.208408-1-angelogioacchino.delregno@collabora.com> Content-Language: en-US From: AngeloGioacchino Del Regno In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Il 07/07/23 10:23, Chen-Yu Tsai ha scritto: > On Thu, Jul 6, 2023 at 8:30 PM AngeloGioacchino Del Regno > wrote: >> >> Changes in v4: >> - Set data lanes to idle to prevent stalls if bootloader didn't >> properly close the eDP port >> - Now using the .done_probing() callback for AUX bus to prevent >> probe deferral loops in case the panel-edp driver is a module >> as previously seen with another bridge driver (ANX7625) on >> some other SoCs (MT8192 and others) >> - Rebased over next-20230706 >> - Dropped Chen-Yu's T-b tag on last patch as some logic changed >> (before, I wasn't using the .done_probing() callback). >> >> Changes in v3: >> - Added DPTX AUX block initialization before trying to communicate >> to stop relying on the bootloader keeping it initialized before >> booting Linux. >> - Fixed commit description for patch [09/09] and removed commented >> out code (that slipped from dev phase.. sorry!). >> >> This series adds "real" support for eDP in the mtk-dp DisplayPort driver. >> >> Explaining the "real": >> Before this change, the DisplayPort driver did support eDP to some >> extent, but it was treating it entirely like a regular DP interface >> which is partially fine, after all, embedded DisplayPort *is* actually >> DisplayPort, but there might be some differences to account for... and >> this is for both small performance improvements and, more importantly, >> for correct functionality in some systems. >> >> Functionality first: >> >> One of the common differences found in various boards implementing eDP >> and machines using an eDP panel is that many times the HPD line is not >> connected. This *must* be accounted for: at startup, this specific IP >> will raise a HPD interrupt (which should maybe be ignored... as it does >> not appear to be a "real" event...) that will make the eDP panel to be >> detected and to actually work but, after a suspend-resume cycle, there >> will be no HPD interrupt (as there's no HPD line in my case!) producing >> a functionality issue - specifically, the DP Link Training fails because >> the panel doesn't get powered up, then it stays black and won't work >> until rebooting the machine (or removing and reinserting the module I >> think, but I haven't tried that). >> >> Now for.. both: >> eDP panels are *e*DP because they are *not* removable (in the sense that >> you can't unplug the cable without disassembling the machine, in which >> case, the machine shall be powered down..!): this (correct) assumption >> makes us able to solve some issues and to also gain a little performance >> during PM operations. >> >> What was done here is: >> - Caching the EDID if the panel is eDP: we're always going to read the >> same data everytime, so we can just cache that (as it's small enough) >> shortening PM resume times for the eDP driver instance; >> - Always return connector_status_connected if it's eDP: non-removable >> means connector_status_disconnected can't happen during runtime... >> this also saves us some time and even power, as we won't have to >> perform yet another power cycle of the HW; >> - Added aux-bus support! >> This makes us able to rely on panel autodetection from the EDID, >> avoiding to add more and more panel timings to panel-edp and, even >> better, allowing to use one panel node in devicetrees for multiple >> variants of the same machine since, at that point, it's not important >> to "preventively know" what panel we have (eh, it's autodetected...!). >> >> This was tested on a MT8195 Cherry Tomato Chromebook (panel-edp on aux-bus) > > Do you have panel-edp built as a module? If I have it built in, the panel > can correctly display stuff. If I have it built as a module, the panel is > correctly detected, but the panel stays black even if DRM thinks it is > displaying stuff. > I tested both. I'll recheck on a clean tree just to be sure... > And it looks like EDID reading and panel power sequencing is still not > working correctly, i.e. needs regulator-always-on? Yeah that's still needed with this version, I'm still trying to get *at least* some support upstreamed before refining it. Cheers, Angelo > > ChenYu > >> P.S.: For your own testing commodity, here's a reference devicetree: >> &edp_tx { >> status = "okay"; >> >> pinctrl-names = "default"; >> pinctrl-0 = <&edptx_pins_default>; >> >> ports { >> #address-cells = <1>; >> #size-cells = <0>; >> >> port@0 { >> reg = <0>; >> edp_in: endpoint { >> remote-endpoint = <&dp_intf0_out>; >> }; >> }; >> >> port@1 { >> reg = <1>; >> edp_out: endpoint { >> data-lanes = <0 1 2 3>; >> remote-endpoint = <&panel_in>; >> }; >> }; >> }; >> >> aux-bus { >> panel: panel { >> compatible = "edp-panel"; >> power-supply = <&pp3300_disp_x>; >> backlight = <&backlight_lcd0>; >> port { >> panel_in: endpoint { >> remote-endpoint = <&edp_out>; >> }; >> }; >> }; >> }; >> }; >> >> >> AngeloGioacchino Del Regno (9): >> drm/mediatek: dp: Cache EDID for eDP panel >> drm/mediatek: dp: Move AUX and panel poweron/off sequence to function >> drm/mediatek: dp: Always return connected status for eDP in .detect() >> drm/mediatek: dp: Always set cable_plugged_in at resume for eDP panel >> drm/mediatek: dp: Change logging to dev for mtk_dp_aux_transfer() >> drm/mediatek: dp: Enable event interrupt only when bridge attached >> drm/mediatek: dp: Use devm variant of drm_bridge_add() >> drm/mediatek: dp: Move AUX_P0 setting to >> mtk_dp_initialize_aux_settings() >> drm/mediatek: dp: Add support for embedded DisplayPort aux-bus >> >> drivers/gpu/drm/mediatek/mtk_dp.c | 197 +++++++++++++++++++----------- >> 1 file changed, 127 insertions(+), 70 deletions(-) >> >> -- >> 2.40.1 >>