From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=91.218.175.52 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794595613; b=KVVGNWbeheEbgWNq2H2zsvepdJGJR7fuKhwJzpnjz5bbL9/pE54dFmfTmzUWru6p9zXo GhG9HiukIVAPyZRkA26uqr0GRkdp207R4CqIDxp7haVcLlOpQU1nbDaLZe3TETIpw4uih xdmeetZcRH+oftbD0/ElORsrbY0xoQMrYYsuciUo8TZXFiKjgMOXgrD2GgaUj9k2/GmfX y/U227uG+w13of6LKE10f1qNZnLPuOA+DRDDzMcJ/1Ipd8+h/iPKhsp3II4Fp56w+iepB h40tOAtydEcRsbCc1FJ13DNs9x95VYPRxmzB28C69vnhoNAMDHVipXria8Y1Nu5QyjA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794595613; h=DMARC-Filter:X-Envelope-To:DKIM-Signature:X-Envelope-To:Received: X-Mizu-Trace-ID:X-Migadu-Flow:Message-ID:Date:MIME-Version:User-Agent: Subject:To:Cc:References:Content-Language:From:In-Reply-To: Content-Type:Content-Transfer-Encoding; bh=jnDAeo7CmnNaA/656fOLCkXGnntEEKJb98BwVbdJVSA=; b=P1iGf1dijJURXKGAhVG++iaVpmY1XCTJlvaRucdXFJkPKbr6laByyWZZmXAonabNoLXt 7nmoH3k6WiZUAjQpvbhGfchpAkEZ5te6ehk92UGDFqGfz4388AAb6+js0154QYSHgv/fW GBGMMSDhKRMBbb2qcdNuZYeRwyFZSq7jkub8qoQtjLM1XIZj/go8kq+P45d8eVbGly6pM JC9gCZ1aB+wI6CJZ/dRsb/WN18v5C8IZcdCTBVvMiz8V0sw11KetM0v5LDgKZ1QAim+uv 4i5Cctnk6TVG0a8U2X4uo5vppU9/pazLLJg+UU34QEqku3ebwu9Tvg+klaIgL2mzjdw== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=packett.cool; spf=pass smtp.mailfrom=packett.cool; dkim=pass header.d=packett.cool header.i=@packett.cool header.a=rsa-sha256 header.s=key1 header.b=wKqlIfso; arc=none smtp.remote-ip=91.218.175.52 Received: from mta0.migadu.com (out-52.mta0.migadu.com [91.218.175.52]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D4F80606A335 for ; Fri, 13 Nov 2026 18:46:52 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org D4F80606A335 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=packett.cool Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=packett.cool Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=packett.cool header.i=@packett.cool header.a=rsa-sha256 header.s=key1 header.b=wKqlIfso X-Envelope-To: linux-kernel@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=YRNPDyKnF5AAnH1Nkcj0IpcYyCLG3qMSgftkaQIlJjM=; c=simple/simple; d=packett.cool; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1794595610; v=1; x=1795200410; b=wKqlIfsoAs0iiPyqGpYb1eUg2O8du+8UjqsDMtpATzTB6foPKYrKEZW3X/GCT6x0Htk3RdMS rYqKk+9j35v5d7UF3Lgka/03jO7vWIae3pT1pqTd3i4mQfDNs8KV5Ho9Rdi1FIH34bCAKLKvKOz Xpm868QO4MtJl7TzQeub6Z4v2Sin4Ltb5EMgyE6mw2mhX8JMm5q7T7KHupDQ5lM0SIvgtD1QKEB yDfLlLnJSWRsFseTjO/pr746/CI5K1dLg8uSdw1YRFRXnF8Iuxl+fqd+QTIRhwy73cr0NDLmqtG kF8OuSRi46q4kYjbqTbjjdB5YLwzVG2yLa+YGTyNhu13g== X-Envelope-To: linux-kernel@vger.kernel.org Received: by smtp.migadu.com with ESMTPS id e856afca2a42441d; Fri, 13 Nov 2026 18:46:50 +0000 X-Mizu-Trace-ID: e856afca2a42441d X-Migadu-Flow: FLOW_OUT Message-ID: <4ce436ed-63b7-4764-afc5-dc5ffa4f0ba1@packett.cool> Date: Fri, 13 Nov 2026 15:46:40 -0300 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 3/6] arm64: dts: qcom: kodiak: Add GEM_NOC interconnect for adreno SMMU To: Bibek Kumar Patro , Bjorn Andersson Cc: Dmitry Baryshkov , Will Deacon , Robin Murphy , Joerg Roedel , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Konrad Dybcio , Rob Clark , linux-arm-kernel@lists.infradead.org, iommu@lists.linux.dev, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org References: <20260706-smmu_interconnect_addition-v3-0-afdca0125a65@oss.qualcomm.com> <20260706-smmu_interconnect_addition-v3-3-afdca0125a65@oss.qualcomm.com> <807f145d-88d3-460a-9862-b63fe2a52cf7@oss.qualcomm.com> <4e5a3d82-b946-4490-885a-ea7061939c32@oss.qualcomm.com> <2c21041d-f84c-4fa7-a977-555f9203d8b5@oss.qualcomm.com> Content-Language: en-US From: Val Packett In-Reply-To: <2c21041d-f84c-4fa7-a977-555f9203d8b5@oss.qualcomm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Hi, On 7/17/26 8:40 AM, Bibek Kumar Patro wrote: > > > On 7/8/2026 8:56 PM, Bjorn Andersson wrote: >> On Wed, Jul 08, 2026 at 03:31:07PM +0530, Bibek Kumar Patro wrote: >>> >>> >>> On 7/7/2026 10:14 PM, Dmitry Baryshkov wrote: >>>> On Tue, Jul 07, 2026 at 06:37:24PM +0530, Bibek Kumar Patro wrote: >>>>> >>>>> >>>>> On 7/6/2026 11:12 PM, Dmitry Baryshkov wrote: >>>>>> On Mon, Jul 06, 2026 at 10:26:36PM +0530, Bibek Kumar Patro wrote: >>>>>>> On Kodiak platforms, the Adreno SMMU requires a bandwidth vote on >>>>>>> the GEM_NOC path (MASTER_GPU_TCU -> SLAVE_EBI1) before its >>>>>>> registers >>>>>>> are accessible. Without this vote, the SMMU may become unreachable, >>>>>>> leading to intermittent probe failures and runtime issues. >>>>>>> >>>>>>> Add the required interconnect to ensure reliable register access. >>>>>>> >>>>>>> Signed-off-by: Bibek Kumar Patro >>>>>>> --- >>>>>>>     arch/arm64/boot/dts/qcom/kodiak.dtsi | 2 ++ >>>>>>>     1 file changed, 2 insertions(+) >>>>>>> >>>>>>> diff --git a/arch/arm64/boot/dts/qcom/kodiak.dtsi >>>>>>> b/arch/arm64/boot/dts/qcom/kodiak.dtsi >>>>>>> index 90e50c245c0c..721526f023dd 100644 >>>>>>> --- a/arch/arm64/boot/dts/qcom/kodiak.dtsi >>>>>>> +++ b/arch/arm64/boot/dts/qcom/kodiak.dtsi >>>>>>> @@ -3389,6 +3389,8 @@ adreno_smmu: iommu@3da0000 { >>>>>>>                 power-domains = <&gpucc GPU_CC_CX_GDSC>; >>>>>>>                 dma-coherent; >>>>>>> +            interconnects = <&gem_noc MASTER_GPU_TCU >>>>>>> QCOM_ICC_TAG_ALWAYS >>>>>>> +                     &mc_virt SLAVE_EBI1 QCOM_ICC_TAG_ALWAYS>; >>>>>> >>>>>> Why is it ALWAYS? Would it be better to declare it as ACTIVE_ONLY >>>>>> and >>>>> >>>>> Added QCOM_ICC_TAG_ALWAYS, to hold the vote in SLEEP bucket as well >>>>> preventing gem_noc going to sleep when icc_set_bw is being called. >>>> >>>> _why_? >>>> >>> >>> Now when i think of where we implemented the hooks, ALWAYS is not >>> needed. We >>> should keep it ACTIVE_ONLY since we are already voting it >>> back in resume pah. I'll fix it in next revision. >>> >> >> The path is between the SMMU and DDR, so clearly it has to do with the >> TCU's ability to fetch things from DDR. >> > > Yes as you rightly mentioned, this series is helping to resolve the > race in TCU DDR clink > >> ACTIVE_ONLY states that the vote should only be applied when the >> application subsystem (CPUSS) is not in low-power mode (CPU is active). >> >> So, are you saying that in all cases that cpuidle might select such >> low-power state the GPU TCU is "stopped", and does not need to perform >> any memory transactions? >> > > I rechecked the architectural block diagram, GPU TCU is > independent of the CPUSS, unlike system TCU. > > This means CPUSS can be powered down while the GPU TCU remains voted > up. While this series was intended to avoid a DDR voting race between the > GPU TCU and its clients, using ACTIVE_ONLY could have possibly > introduced a race between CPUSS and the GPU TCU itself. > > Thanks for catching this in my reply Bjorn. > > ACTIVE_ONLY would have been suitable for system TCU (apps_smmu) > for which the interconnect field is anyways not needed, but > unsuitable for GPU TCU. > >> >> To me these two are orthogonal and TAG_ALWAYS is logically correct, but >> perhaps there's some practical dependency that I'm missing? >> > > We can ignore my acknowledgment [1] on previous response, Dmitry. > ALWAYS TAG is correct here instead of ACTIVE_ONLY in the interconnect > field for adreno SMMU. This series seems to help with a really annoying bug on Kodiak phones like sm7325-motorola-dubai where often boot would hang when initializing the display panel (so it took a few reboots to successfully boot the device). And indeed it only helps with the ALWAYS tag.. I've had this patch applied for a while (without even realizing that it fixed that!! thought the issue was gone because of something else) and today I went around kodiak.dtsi trying to remove unnecessary ALWAYS votes… first boot after changing this tag to ACTIVE_ONLY and boom, hang. Tested-by: Val Packett # sm7325-motorola-dubai (for patch 2 i.e. the driver code as well) Thanks, ~val