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 BC6ECCD5BD5 for ; Wed, 27 May 2026 13:53:32 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 5EDA810E7C5; Wed, 27 May 2026 13:53:32 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=intel.com header.i=@intel.com header.b="XudC6/aA"; dkim-atps=neutral Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.17]) by gabe.freedesktop.org (Postfix) with ESMTPS id B775110E106; Wed, 27 May 2026 13:53:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1779890011; x=1811426011; h=date:from:to:cc:subject:message-id:references: mime-version:content-transfer-encoding:in-reply-to; bh=HMhVZCDTnX1vcdC4g6fRFUA+elHTRzFClqwaPTSmEdQ=; b=XudC6/aA0QgJ8FfbzOQRSybHSdWUpwCYgD5z9XhQPxSy5YyPIE5+lihc GCeiR6SA2dkTKBLdsNUdl+73s7egms0B34JznDwHO7vO4JexE+aIueTs7 rPH+V4drnY4itv5Lq3HiPVcNyezNFx47qVqzTjWamCZfxbaA0qyaTzOQS yg70jKmf2X16wILJtDSWjHXsOoe8FAPW4l/pcKdPYyuoskcbSYGMHmXEI DAxcVsoEVgbmJ0hdHRZMO3UPD/2LQRaPSAqpovxY4jL4j08JGyOVCk5uF xGIzHxNZ9qzUwi7D3l/km4COhJo5LER1ubkcGvV1Q9r280ysB3u1LMpRQ g==; X-CSE-ConnectionGUID: 0GXnbBM1S/mlRr0/f6aKrw== X-CSE-MsgGUID: N6vWJWcDSiSgoLfRJENLaw== X-IronPort-AV: E=McAfee;i="6800,10657,11799"; a="80569526" X-IronPort-AV: E=Sophos;i="6.24,171,1774335600"; d="scan'208";a="80569526" Received: from orviesa004.jf.intel.com ([10.64.159.144]) by fmvoesa111.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 27 May 2026 06:53:30 -0700 X-CSE-ConnectionGUID: ClUl9v0NRwCmss1aMoDyCg== X-CSE-MsgGUID: aMYHQDb4Rm6/7z5Vn6cH3w== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.24,171,1774335600"; d="scan'208";a="246527783" Received: from black.igk.intel.com ([10.91.253.5]) by orviesa004.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 27 May 2026 06:53:27 -0700 Date: Wed, 27 May 2026 15:53:24 +0200 From: Raag Jadav To: Zhan Wei Cc: Matthew Brost , Thomas =?iso-8859-1?Q?Hellstr=F6m?= , Rodrigo Vivi , Andi Shyti , David Airlie , Simona Vetter , Guenter Roeck , intel-xe@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-hwmon@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH] drm/xe/hwmon: report a single fan for DG2 instead of two Message-ID: References: <20260527115311.13398-1-zhanwei919@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20260527115311.13398-1-zhanwei919@gmail.com> 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, May 27, 2026 at 07:53:11PM +0800, Zhan Wei wrote: > xe_hwmon_pcode_read_fan_control() currently hardcodes *uval = 2 when > queried with FSC_READ_NUM_FANS on DG2. This causes fan2_input to be > exposed via sysfs, but on the tested Arc A750 LE (DG2 G10, PCI ID > 0x56a1) fan2_input reads 0 RPM permanently while fan1_input correctly > reports ~800 RPM with both physical fan physically spinning. > > The RPM is calculated delta-based from a tach pulse counter: > > rotations = (reg_val - fi->reg_val_prev) / 2; > > so a constant-zero RPM means the register at offset 0x138170 > (BMG_FAN_2_SPEED) simply does not accumulate pulses on DG2 silicon. > The i915 driver does not expose fan2 on DG2 at all -- it only maps > PCU_PWM_FAN_SPEED (0x138140, identical to BMG_FAN_1_SPEED), consistent > with the observation that only one fan tach register is wired on DG2. i915 is for legacy cards (like DG1) which only has a single channel in hardware. I just happen to extend the support to DG2 for the folks that might be using it. > Report a single fan for DG2 to keep the phantom fan2_input out of > sysfs. Battlemage paths are unchanged. > > Tested on Arc A750 LE (DG2 G10): with this patch applied, fan2_input > no longer appears in /sys/class/hwmon/hwmonX/ and `sensors xe-pci-0300` > shows fan1 only. > > Fixes: 28f79ac609de ("drm/xe/hwmon: expose fan speed") > Signed-off-by: Zhan Wei > --- > Open questions for reviewers: this is verified only on DG2 G10. Owners > of G11 (e.g. ASRock Challenger A750) and G12 (e.g. Sparkle Titan A750 > with three physical fans) -- does fan2_input or fan3_input ever read > non-zero in your setup? If so, the right fix is a per-subplatform > table rather than a flat 1. There's no straight answer here :) root@DUT2147DG2FRD:/home/gta# cat /sys/class/drm/card0/device/device 0x56a1 root@DUT2147DG2FRD:/home/gta# sensors xe-pci-0300 xe-pci-0300 Adapter: PCI adapter pkg: 758.00 mV fan1: 636 RPM fan2: 652 RPM pkg: +47.0°C vram: +50.0°C pkg: N/A (max = 190.00 W) pkg: 14.37 kJ The way this works is upto the OEMs how they design their cards. Some reuse a single channel for multiple physical fans while some use 1:1 mapped multiple channels for each fan. This is unfortunately not possible to figure out from the driver without FSC_READ_NUM_FANS command (which has been found to be not working on some cards and hence the hardcoded value). Raag > drivers/gpu/drm/xe/xe_hwmon.c | 10 ++++++++-- > 1 file changed, 8 insertions(+), 2 deletions(-) > > diff --git a/drivers/gpu/drm/xe/xe_hwmon.c b/drivers/gpu/drm/xe/xe_hwmon.c > index de3f2aeffc3f..2a60a76b1971 100644 > --- a/drivers/gpu/drm/xe/xe_hwmon.c > +++ b/drivers/gpu/drm/xe/xe_hwmon.c > @@ -860,9 +860,15 @@ static int xe_hwmon_pcode_read_fan_control(const struct xe_hwmon *hwmon, u32 sub > { > struct xe_tile *root_tile = xe_device_get_root_tile(hwmon->xe); > > - /* Platforms that don't return correct value */ > + /* > + * The PCODE FAN_SPEED_CONTROL subcommands return an error on DG2, so we > + * answer the FSC_READ_NUM_FANS query here. DG2 only wires a single fan > + * tachometer register (BMG_FAN_1_SPEED == 0x138140, shared with i915's > + * PCU_PWM_FAN_SPEED); BMG_FAN_2/3_SPEED read 0 on DG2 silicon. Reporting > + * one fan keeps a phantom fan2_input that always reads 0 out of sysfs. > + */ > if (hwmon->xe->info.platform == XE_DG2 && subcmd == FSC_READ_NUM_FANS) { > - *uval = 2; > + *uval = 1; > return 0; > } > > -- > 2.43.0 >