From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 290921DF99F for ; Tue, 11 Feb 2025 18:34:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739298874; cv=none; b=YSHjVBxzwbR/mnxVc1WmtYSKooqiSFFa1i7fBLF1yyks6JxAFH+vL7YYzZXO5ShhrTNCTC767LgiVeCkw61wS+9SSXvJFhHhNpsHRX2J9Y+2dJPXZOZnGO0YZtVUxusezRczok7AHQOmH1dABJXfNXyNWCD3gn9isfIunekojAU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739298874; c=relaxed/simple; bh=TvhfNc3I07qiTd32YHIKmw3g9aChxrMBZe65U1A7VhQ=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=UfuOSBo5gOSPWowA1xmuzvUmOgv5nvcDgfV6G9Np3BiM+JgUnfhNf30HzBfAcWWKcQIEHb/2Dqvza0A6wjRaesGYbEB0xwUuRCRXmsAcJfFRL811hofVsX3lbdEoCoDwW5lCRcuon69hpOOm/St1ykUFt2FfqRvWMIuGh1rjYL4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com 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 DDA0E13D5; Tue, 11 Feb 2025 10:34:53 -0800 (PST) Received: from [10.57.35.63] (unknown [10.57.35.63]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 2C11D3F58B; Tue, 11 Feb 2025 10:34:30 -0800 (PST) Message-ID: <98af5c02-5006-4272-aaf0-a0e30c312059@arm.com> Date: Tue, 11 Feb 2025 18:34:27 +0000 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 2/5] iommu/dart: Skip reset for locked DARTs To: Alyssa Rosenzweig , Sven Peter , Janne Grunau , Joerg Roedel , Will Deacon Cc: asahi@lists.linux.dev, linux-arm-kernel@lists.infradead.org, iommu@lists.linux.dev, linux-kernel@vger.kernel.org, Hector Martin References: <20250210-locked-dart-v1-0-5d97fe247f35@rosenzweig.io> <20250210-locked-dart-v1-2-5d97fe247f35@rosenzweig.io> From: Robin Murphy Content-Language: en-GB In-Reply-To: <20250210-locked-dart-v1-2-5d97fe247f35@rosenzweig.io> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 2025-02-10 7:39 pm, Alyssa Rosenzweig wrote: > Locked DARTs cannot be reconfigured, therefore the reset/restore > procedure can't work and should not be needed. Skip it, allowing locked > DARTs to probe. > > Co-developed-by: Hector Martin > Signed-off-by: Hector Martin > Signed-off-by: Alyssa Rosenzweig > --- > drivers/iommu/apple-dart.c | 24 ++++++++++++------------ > 1 file changed, 12 insertions(+), 12 deletions(-) > > diff --git a/drivers/iommu/apple-dart.c b/drivers/iommu/apple-dart.c > index 460cf96bc8001e051916f356d5d175b35e36c608..9c74a95eb7e819e94ab2fb47ed0d411a1eba8bf7 100644 > --- a/drivers/iommu/apple-dart.c > +++ b/drivers/iommu/apple-dart.c > @@ -452,17 +452,9 @@ apple_dart_t8110_hw_invalidate_tlb(struct apple_dart_stream_map *stream_map) > > static int apple_dart_hw_reset(struct apple_dart *dart) > { > - u32 config; > struct apple_dart_stream_map stream_map; > int i; > > - config = readl(dart->regs + dart->hw->lock); > - if (config & dart->hw->lock_bit) { > - dev_err(dart->dev, "DART is locked down until reboot: %08x\n", > - config); > - return -EINVAL; > - } > - > stream_map.dart = dart; > bitmap_zero(stream_map.sidmap, DART_MAX_STREAMS); > bitmap_set(stream_map.sidmap, 0, dart->num_streams); > @@ -1151,9 +1143,11 @@ static int apple_dart_probe(struct platform_device *pdev) > } > > dart->locked = apple_dart_is_locked(dart); > - ret = apple_dart_hw_reset(dart); > - if (ret) > - goto err_clk_disable; > + if (!dart->locked) { > + ret = apple_dart_hw_reset(dart); > + if (ret) > + goto err_clk_disable; > + } > > ret = request_irq(dart->irq, dart->hw->irq_handler, IRQF_SHARED, > "apple-dart fault handler", dart); > @@ -1192,7 +1186,9 @@ static void apple_dart_remove(struct platform_device *pdev) > { > struct apple_dart *dart = platform_get_drvdata(pdev); > > - apple_dart_hw_reset(dart); > + if (!dart->locked) > + apple_dart_hw_reset(dart); Not much point saving anything on suspend either, in that case. Thanks, Robin. > + > free_irq(dart->irq, dart); > > iommu_device_unregister(&dart->iommu); > @@ -1325,6 +1321,10 @@ static __maybe_unused int apple_dart_resume(struct device *dev) > unsigned int sid, idx; > int ret; > > + /* Locked DARTs can't be restored, and they should not need it */ > + if (dart->locked) > + return 0; > + > ret = apple_dart_hw_reset(dart); > if (ret) { > dev_err(dev, "Failed to reset DART on resume\n"); >