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 AFF71C5DF93 for ; Fri, 21 Aug 2026 14:19:42 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 3F10410E0A5; Fri, 21 Aug 2026 14:19:42 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=intel.com header.i=@intel.com header.b="f3fc42g4"; dkim-atps=neutral Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.10]) by gabe.freedesktop.org (Postfix) with ESMTPS id 4BDF510E0A5; Fri, 21 Aug 2026 14:19:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1787321981; x=1818857981; h=date:from:to:cc:subject:message-id:references: mime-version:content-transfer-encoding:in-reply-to; bh=z8iAxAemn/0JgPj6PTSNSzKHXE5ttv1nlKOgH4UXlm8=; b=f3fc42g4r67o4M5QcIiohc57+sJwF6jeNaxMqW+tEY1Kl3TR8FXX6wNi rnl9Bze2/4MnKIT5JLbsRed7lWxA5rQskgISLX+NsODCD3ehmomhnhG5K Yv9elfLJv4yZox9XLp+0N2We+Xx+u+7Y0s5snUyzfM85PfQ/VfuHTEIlv rqYIE7qskdkfLcrcPPM8pfTk7vuGiDEwKjmuDvFq0v5ffBGbLcmZUbw8p JRIKYxJKtwRwDM47NbAms++KuE5h3xaoI8McHunn0H+IZoK5bPeRCWU8Y LwYTlBe3PvP3qP4eJjSmrgOZvw624PE2lGVNItX4+TgOemLRALrfE+mtE g==; X-CSE-ConnectionGUID: hriM9syATUOY+pHFuKuBUg== X-CSE-MsgGUID: mDrlPdSoRbyZOW93XcZNwA== X-IronPort-AV: E=McAfee;i="6800,10657,11882"; a="99227883" X-IronPort-AV: E=Sophos;i="6.25,235,1779174000"; d="scan'208";a="99227883" Received: from orviesa003.jf.intel.com ([10.64.159.143]) by fmvoesa104.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 21 Aug 2026 07:19:41 -0700 X-CSE-ConnectionGUID: Z41FSKHpRRClrP8NuXTugg== X-CSE-MsgGUID: JRl2iDgJTUeeglFRpLcyOg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.25,235,1779174000"; d="scan'208";a="269840184" Received: from abityuts-desk1.ger.corp.intel.com (HELO localhost) ([10.245.244.20]) by ORVIESA003-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 21 Aug 2026 07:19:37 -0700 Date: Fri, 21 Aug 2026 17:19:33 +0300 From: Ville =?iso-8859-1?Q?Syrj=E4l=E4?= To: Jani Nikula Cc: Chang =?utf-8?B?Smlvbmco5bi454KvKQ==?= , intel-gfx@lists.freedesktop.org, stable@vger.kernel.org, Rodrigo Vivi , Joonas Lahtinen , Tvrtko Ursulin , David Airlie , Simona Vetter , =?utf-8?Q?Micha=C5=82?= Grzelak , "open list:INTEL DRM DISPLAY FOR XE AND I915 DRIVERS" , "open list:DRM DRIVERS" , open list Subject: Re: [PATCH v2] drm/i915/cdclk: Don't force cd2x pipe select on Xe3 in bxt_sanitize_cdclk() Message-ID: References: <20260816062344.796615-1-xspeed1989@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Patchwork-Hint: comment Organization: Intel Finland Oy - BIC 0357606-4 - c/o Alberga Business Park, 6 krs Bertel Jungin Aukio 5, 02600 Espoo, Finland X-BeenThere: intel-xe@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel Xe graphics driver List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-xe-bounces@lists.freedesktop.org Sender: "Intel-xe" On Wed, Aug 19, 2026 at 12:33:56PM +0300, Jani Nikula wrote: > On Tue, 18 Aug 2026, Jani Nikula wrote: > > On Sun, 16 Aug 2026, Chang Jiong(常炯) wrote: > >> Since commit 2ee8dbd880b1 ("drm/i915/cdclk: Fix up CDCLK_FREQ_DECIMAL > >> without a full PLL re-enable") bxt_sanitize_cdclk() normalizes the > >> CD2X pipe select field of the CDCLK_CTL readback to PIPE_NONE before > >> comparing against the expected value. > >> > >> However bxt_cdclk_ctl() does not include the CD2X pipe select field > >> at all on DISPLAY_VER() >= 30, so on Xe3 (PTL) the normalized > >> readback (pipe field forced to the PIPE_NONE encoding, 0b111) can > >> never match the expected value (pipe field 0). The comparison now > >> fails on every boot and we always take the full CDCLK PLL > >> disable+re-enable path with the BIOS framebuffer actively scanning > >> out - exactly what this code was trying to avoid. On a Panther Lake > >> laptop (Arc B390, 8086:b080, eDP 3120x2080@120) this causes > >> "CPU pipe A FIFO underrun" during probe and persistent full-screen > >> scanout corruption for the first KMS client (the SDDM greeter); > >> the corruption lasts until the next full modeset. > >> > >> Only normalize the CD2X pipe select field on platforms where > >> bxt_cdclk_ctl() actually programs it, mirroring its DISPLAY_VER() > >> check. > >> > >> Fixes: 2ee8dbd880b1 ("drm/i915/cdclk: Fix up CDCLK_FREQ_DECIMAL without a full PLL re-enable") > >> Cc: stable@vger.kernel.org > >> Signed-off-by: Chang Jiong(常炯) > > > > Reviewed-by: Jani Nikula > > Closes: https://gitlab.freedesktop.org/drm/xe/kernel/-/work_items/8550 > > Closes: https://gitlab.freedesktop.org/drm/xe/kernel/-/work_items/8569 > > Closes: https://gitlab.freedesktop.org/drm/xe/kernel/-/work_items/8901 > > > > The first one has a patch from Ville that is identical to this one. > > > > I'll try to kick CI to get this tested before merging. > > Okay, the patch is against some stable kernel, not against the current > development tree. Please rebase on top of the drm-tip branch of the > drm-tip repository. I pushed my original fix and closed the other bugs as duplicates. -- Ville Syrjälä Intel