From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 303B128B7DB; Wed, 12 Nov 2025 07:26:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762932369; cv=none; b=CxV6G8twU/RRtOrlOrKFJMw9QMChzgQEyniqCSuf4PEQtpR2ezjtgiXwe/mi/bZiLbntk0EfdXukn5GoLNqz+B9tkbz37KddzDACwHDyTghg+4M+cBlpsJLcHvrb6dlF5Er40IhjrGHTb/r/wyFK2eHpwQTd5hUoS2FvTazb85k= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762932369; c=relaxed/simple; bh=MpC7Q8sfu2Zx/rwI4rNxHM4rwj5juiLT2PNkIDphY5A=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=SesQk6zSUWHqTb4fGanSYjlRWugCb/HOUFtYT4lDovgZkS6ey2W4KQDe1P6ee2DVJoKt5USw2yppv/pJguKEjhGRoA0V/Qd9FasFIIrUTUyA4/k/WoGPpWb65UPxoVAxhVesdi3UEmwbQ+NSrMmZLCFf43z63Up04quNjDLkYf4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ItQrnS80; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="ItQrnS80" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B4AA6C4CEF7; Wed, 12 Nov 2025 07:26:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1762932368; bh=MpC7Q8sfu2Zx/rwI4rNxHM4rwj5juiLT2PNkIDphY5A=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=ItQrnS80UYRJ2NCOkmi+R+sKn6m7TYVXX/1irdajGbjSZsPxUUYpoF1sAWT/k1xDu ZaR0XSKH0WiYX6ABxNn2J/KYcplHi4R6LDbzUtb5yWisoI5hqWHggbijuWgSXaG3tm s0UJXWWOj3gpNraQKeLeAFYokSSs9Hld6wonU2VvMH3nUWjPu3ANoJyLH41J1UKeQF SBcVl6I+rRzT5DIJdi3KLv7AiRagy47z0sT6Q1DbKBJQPV0DbzgNfYocQk8nL85k9r GGf61MavAGqQ82XjUcvQ4WV3ZD37JPBwQJwHKHYRBd7HsD5B7x9ZtwQKeOfHlmOsLL qSNsUj2HyNSrw== Message-ID: Date: Wed, 12 Nov 2025 08:26:04 +0100 Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 3/5] memory: tegra186-emc: Support non-bpmp icc scaling To: Aaron Kling , Jon Hunter Cc: Rob Herring , Conor Dooley , Thierry Reding , linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, linux-tegra@vger.kernel.org References: <20251027-tegra186-icc-p2-v4-0-e4e4f57e2103@gmail.com> <20251027-tegra186-icc-p2-v4-3-e4e4f57e2103@gmail.com> <82c8dda8-6fcb-48f9-bdaa-f3d1431e41ae@nvidia.com> <99ca4992-5736-417d-854e-379542549bee@kernel.org> <7f3dad08-cff5-40c2-8e7f-f6441a3d6b91@nvidia.com> <249bbe7e-e2da-4493-bdd5-8f4b17aff8fe@nvidia.com> From: Krzysztof Kozlowski Content-Language: en-US Autocrypt: addr=krzk@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 12/11/2025 00:17, Aaron Kling wrote: >> >> The actual rate that is set is 408MHz if I read the rate after >> it is set ... >> >> [ 13.912099] tegra186_emc_icc_set_bw-362: rate 408000000 >> >> This is a simple boot test and so nothing we are doing via >> debugfs/sysfs to influence this. > > Alright, I think I've got the picture of what's going on now. The > standard arm64 defconfig enables the t194 pcie driver as a module. And > my simple busybox ramdisk that I use for mainline regression testing > isn't loading any modules. If I set the pcie driver to built-in, I > replicate the issue. And I don't see the issue on my normal use case, > because I have the dt changes as well. > > So it appears that the pcie driver submits icc bandwidth. And without > cpufreq submitting bandwidth as well, the emc driver gets a very low > number and thus sets a very low emc freq. The question becomes... what If this depends on DT changes then it is obvious ABI break. Nothing in commit msgs explained ABI impact. > to do about it? If the related dt changes were submitted to > linux-next, everything should fall into place. And I'm not sure where > this falls on the severity scale since it doesn't full out break boot > or prevent operation. > > Aaron Best regards, Krzysztof