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 C1E78C04A94 for ; Wed, 2 Aug 2023 19:12:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232850AbjHBTMx (ORCPT ); Wed, 2 Aug 2023 15:12:53 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60686 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229832AbjHBTMr (ORCPT ); Wed, 2 Aug 2023 15:12:47 -0400 Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [213.167.242.64]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1AD062D49 for ; Wed, 2 Aug 2023 12:12:36 -0700 (PDT) Received: from pendragon.ideasonboard.com (213-243-189-158.bb.dnainternet.fi [213.243.189.158]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 93AC429A; Wed, 2 Aug 2023 21:11:30 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1691003490; bh=79gCi+ljQNxU5kGfbaU4eODO3ztjzxCR2y1UIHcBH+A=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=SPEG/sa7I0CPMVolb6AYy5D/t2GM+kTk/VrYzBMUVpHC/7u45CCt4N1iDdakbFR6D 5bJZWgd5TvYP3IVWRifufmCS01sQguhRL+w74YoP2NLWw7lnFH0XzoL9Mf9wDYehR0 f6LGCI4oHEwAEOh+K3Kd8f1klINbupJ8eREDknUY= Date: Wed, 2 Aug 2023 22:12:39 +0300 From: Laurent Pinchart To: Dmitry Baryshkov Cc: Marek Vasut , Amit Pundir , Neil Armstrong , Robert Foss , Jonas Karlman , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, Jernej Skrabec , Abhinav Kumar , Andrzej Hajda , Jagan Teki Subject: Re: [PATCH] Revert "drm/bridge: lt9611: Do not generate HFP/HBP/HSA and EOT packet" Message-ID: <20230802191239.GA1142@pendragon.ideasonboard.com> References: <20230802-revert-do-not-generate-hfp-hbp-hsa-eot-packet-v1-1-f8a20084e15a@linaro.org> <5cf0e3fa-f66d-06c4-cfda-c48efd8c6508@linaro.org> <69900221-503a-693a-f52e-cfa5841230a6@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <69900221-503a-693a-f52e-cfa5841230a6@linaro.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Aug 02, 2023 at 09:49:42PM +0300, Dmitry Baryshkov wrote: > On 02/08/2023 21:45, Marek Vasut wrote: > > On 8/2/23 20:16, Dmitry Baryshkov wrote: > >> On Wed, 2 Aug 2023 at 20:34, Marek Vasut wrote: > >>> On 8/2/23 15:38, Dmitry Baryshkov wrote: > >>>> On 02/08/2023 11:52, Neil Armstrong wrote: > >>>>> This reverts commit [1] to fix display regression on the > >>>>> Dragonboard 845c > >>>>> (SDM845) devboard. > >>>>> > >>>>> There's a mismatch on the real action of the following flags: > >>>>> - MIPI_DSI_MODE_VIDEO_NO_HSA > >>>>> - MIPI_DSI_MODE_VIDEO_NO_HFP > >>>>> - MIPI_DSI_MODE_VIDEO_NO_HBP > >>>>> which leads to a non-working display on qcom platforms. > >>>>> > >>>>> [1] 8ddce13ae696 ("drm/bridge: lt9611: Do not generate HFP/HBP/HSA and > >>>>> EOT packet") > >>>>> > >>>>> Cc: Marek Vasut > >>>>> Cc: Robert Foss > >>>>> Cc: Jagan Teki > >>>>> Cc: Dmitry Baryshkov > >>>>> Cc: Abhinav Kumar > >>>>> Fixes: 8ddce13ae69 ("drm/bridge: lt9611: Do not generate HFP/HBP/HSA > >>>>> and EOT packet") > >>>>> Reported-by: Amit Pundir > >>>>> Link: > >>>>> https://lore.kernel.org/r/CAMi1Hd0TD=2z_=bcDrht3H_wiLvAFcv8Z-U_r_KUOoeMc6UMjw@mail.gmail.com/ > >>>>> Signed-off-by: Neil Armstrong > >>>>> --- > >>>>>    drivers/gpu/drm/bridge/lontium-lt9611.c | 4 +--- > >>>>>    1 file changed, 1 insertion(+), 3 deletions(-) > >>>>> > >>>> Acked-by: Dmitry Baryshkov #fix db845c > >>>> > >>>> The boards broken by [1] are used in production by different parties > >>>> since 5.10, breaking them doesn't seem more acceptable than breaking the > >>>> new out-of-tree iMX8m hardware. > >>> > >>> The MX8M is also in-tree, so this does not apply. > >> > >> v6.5-rc4: > >> > >> $ git grep lontium,lt9611 | grep -v 9611uxc > >> Documentation/devicetree/bindings/display/bridge/lontium,lt9611.yaml:$id: > >> http://devicetree.org/schemas/display/bridge/lontium,lt9611.yaml# > >> Documentation/devicetree/bindings/display/bridge/lontium,lt9611.yaml: > >>      - lontium,lt9611 > >> Documentation/devicetree/bindings/display/bridge/lontium,lt9611.yaml: > >>        compatible = "lontium,lt9611"; > >> arch/arm64/boot/dts/qcom/sdm845-db845c.dts: compatible = "lontium,lt9611"; > >> drivers/gpu/drm/bridge/lontium-lt9611.c: { "lontium,lt9611", 0 }, > >> drivers/gpu/drm/bridge/lontium-lt9611.c: { .compatible = "lontium,lt9611" }, > >> > >> next-20230802: > >> > >> $ git grep lontium,lt9611 | grep -v 9611uxc > >> Documentation/devicetree/bindings/display/bridge/lontium,lt9611.yaml:$id: > >> http://devicetree.org/schemas/display/bridge/lontium,lt9611.yaml# > >> Documentation/devicetree/bindings/display/bridge/lontium,lt9611.yaml: > >>      - lontium,lt9611 > >> Documentation/devicetree/bindings/display/bridge/lontium,lt9611.yaml: > >>        compatible = "lontium,lt9611"; > >> arch/arm64/boot/dts/qcom/sdm845-db845c.dts: compatible = "lontium,lt9611"; > >> drivers/gpu/drm/bridge/lontium-lt9611.c: { "lontium,lt9611", 0 }, > >> drivers/gpu/drm/bridge/lontium-lt9611.c: { .compatible = "lontium,lt9611" }, > >> > >> Your device is not in the tree. Your commit broke existing users. > > > > These devices are in tree: > > arch/arm64/boot/dts/freescale/imx8mm-data-modul-edm-sbc.dts > > arch/arm64/boot/dts/freescale/imx8mp-data-modul-edm-sbc.dts > > > > The LT9211 and LT9611 are both expansion modules handled by DTOs and > > bound to the DSIM (which is also in tree). > > And they DT for them is not in the tree, that was my point. You have > broken the existing user for the DTBO that is not present even in > linux-next. > > >> Can we please end the argument, land the fix (this revert) for 6.5 and > >> work on the solution for 6.6 or 6.7? > > > > I would much prefer a solution which does not break my existing use > > case. It is still not even clear whether the problem really is on MX8M > > side at all, or whether it is QCOM misinterpreting flags. I cannot debug > > the later, since I have no access to that platform, nor its documentation. > > You can get the RB1 for $199 and check the DSI behaviour on that > platform. It has newer bridge, but the DSI controller is (mostly) the same. Could everybody please get away from the keyboard for a few hours, take a deep breath, and resume the discussion in a less aggressive and more constructive way ? Without judging the technical merits of the arguments, and which platform gets it wrong, the commit being reverted landed in v6.5-rc1, and breaks in-tree users. Reverting and retrying thus seems the usual practice to me, as we are getting too close to the v6.5 release to ensure a correct fix can be developed and merged in time. This will not cause a regression on i.MX8M, as the commit has never appeared in a release kernel. This is however an unfortunate event. It is not a nice feeling to work on enabling features for a platform and see the work being reverted at the last minute. Neil, Dmitry, could you please help Marek figuring out a good solution for v6.6 ? I don't think it's reasonable to ask him to buy an RB1 and investigate the MSM side, when Linaro has access to hardware and support. -- Regards, Laurent Pinchart