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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 3617CE674AF for ; Mon, 22 Dec 2025 13:43:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=hkIdtbm3vg4nodeqjiJwMSQ3Vk9rASnees/QYeheYTs=; b=iMvZ2Po1QgrzSASj6guYPBeDu2 3fC+xPG1PdOKCtcCdCqW1rhWlN9HO962O+15xvCYZZUzNIIbRXGdOc0VDEmgUyIAPmtLuJ5vNrH2L 7LzQwuGXK/PRLwUpghe1y/YPbKe9O3bKwhGId5EaAFtVbTexHkvPnaApO43Kpdq8RpIQ7YIP8oxFp OWdeOV5UMu8JbZqo4l/6qObTAsvMYoStGKb0e/OrHr6YHodF1HLl8jV1ecK7VZyI727Dnqz4S8slu VA/QpouxTkf88vdPcGv/w+3fKYiZlHV32k1T7dySI/YCe5xqQNJGfVvmliKGuR0xPJmc/VM0q4BaP D3tbLKyw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vXgBn-0000000DpfE-0Xbg; Mon, 22 Dec 2025 13:43:07 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vXgBi-0000000DpeI-46FS for linux-arm-kernel@lists.infradead.org; Mon, 22 Dec 2025 13:43:04 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id CCC661515 for ; Mon, 22 Dec 2025 05:42:52 -0800 (PST) Received: from [169.254.77.58] (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id A21B43F778 for ; Mon, 22 Dec 2025 05:42:59 -0800 (PST) Date: Mon, 22 Dec 2025 13:41:52 +0000 From: Liviu Dudau To: Nicolas Frattaroli Cc: Boris Brezillon , Steven Price , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Matthias Brugger , AngeloGioacchino Del Regno , Ulf Hansson , Chen-Yu Tsai , Chia-I Wu , kernel@collabora.com, dri-devel@lists.freedesktop.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org, linux-pm@vger.kernel.org Subject: Re: [PATCH v2 3/4] drm/panthor: Implement reading shader_present from nvmem Message-ID: References: <20251220-mt8196-shader-present-v2-0-45b1ff1dfab0@collabora.com> <20251220-mt8196-shader-present-v2-3-45b1ff1dfab0@collabora.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20251220-mt8196-shader-present-v2-3-45b1ff1dfab0@collabora.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20251222_054303_968505_8B035812 X-CRM114-Status: GOOD ( 23.33 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Sat, Dec 20, 2025 at 07:49:54PM +0100, Nicolas Frattaroli wrote: > On some platforms, notably MediaTek MT8196, the shader_present bitmask > in the Mali GPU register for it has cores enabled that may be faulty. > The true shader_present bitmask is found in an efuse instead. > > Implement reading shader_present from an nvmem cell if one is present, > falling back to the Mali register if it's absent. The error codes are > trickled up through to the probe function so that probe deferral works. > > Signed-off-by: Nicolas Frattaroli Reviewed-by: Liviu Dudau Best regards, Liviu > --- > drivers/gpu/drm/panthor/panthor_hw.c | 36 ++++++++++++++++++++++++++++++------ > 1 file changed, 30 insertions(+), 6 deletions(-) > > diff --git a/drivers/gpu/drm/panthor/panthor_hw.c b/drivers/gpu/drm/panthor/panthor_hw.c > index 87ebb7ae42c4..80c521784cd3 100644 > --- a/drivers/gpu/drm/panthor/panthor_hw.c > +++ b/drivers/gpu/drm/panthor/panthor_hw.c > @@ -1,6 +1,7 @@ > // SPDX-License-Identifier: GPL-2.0 or MIT > /* Copyright 2025 ARM Limited. All rights reserved. */ > > +#include > #include > > #include "panthor_device.h" > @@ -109,7 +110,25 @@ static char *get_gpu_model_name(struct panthor_device *ptdev) > return "(Unknown Mali GPU)"; > } > > -static void panthor_gpu_info_init(struct panthor_device *ptdev) > +static int overload_shader_present(struct panthor_device *ptdev) > +{ > + u64 contents; > + int ret; > + > + ret = nvmem_cell_read_variable_le_u64(ptdev->base.dev, "shader-present", > + &contents); > + if (!ret) > + ptdev->gpu_info.shader_present = contents; > + else if (ret == -ENOENT) > + return 0; > + else > + return dev_err_probe(ptdev->base.dev, ret, > + "Failed to read shader-present nvmem cell\n"); > + > + return 0; > +} > + > +static int panthor_gpu_info_init(struct panthor_device *ptdev) > { > unsigned int i; > > @@ -143,13 +162,18 @@ static void panthor_gpu_info_init(struct panthor_device *ptdev) > ptdev->gpu_info.tiler_present = gpu_read64(ptdev, GPU_TILER_PRESENT); > ptdev->gpu_info.l2_present = gpu_read64(ptdev, GPU_L2_PRESENT); > } > + > + return overload_shader_present(ptdev); > } > > -static void panthor_hw_info_init(struct panthor_device *ptdev) > +static int panthor_hw_info_init(struct panthor_device *ptdev) > { > u32 major, minor, status; > + int ret; > > - panthor_gpu_info_init(ptdev); > + ret = panthor_gpu_info_init(ptdev); > + if (ret) > + return ret; > > major = GPU_VER_MAJOR(ptdev->gpu_info.gpu_id); > minor = GPU_VER_MINOR(ptdev->gpu_info.gpu_id); > @@ -172,6 +196,8 @@ static void panthor_hw_info_init(struct panthor_device *ptdev) > "shader_present=0x%0llx l2_present=0x%0llx tiler_present=0x%0llx", > ptdev->gpu_info.shader_present, ptdev->gpu_info.l2_present, > ptdev->gpu_info.tiler_present); > + > + return 0; > } > > static int panthor_hw_bind_device(struct panthor_device *ptdev) > @@ -218,7 +244,5 @@ int panthor_hw_init(struct panthor_device *ptdev) > if (ret) > return ret; > > - panthor_hw_info_init(ptdev); > - > - return 0; > + return panthor_hw_info_init(ptdev); > } > > -- > 2.52.0 >