From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wm1-f49.google.com (mail-wm1-f49.google.com [209.85.128.49]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 27F301EF080 for ; Thu, 20 Feb 2025 10:09:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.49 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740046186; cv=none; b=tUIKzy/hRicfakB4aoIC+621FzZMEt7jj9mtneX8Qg4Y9L3XLKjdFKIqZ/upVlbqF/+35CVH+3FcG5t5l5Z6CnYUISnzW+sP+pIofeJ/SQArLJ+3xSTyuCFEIz+i2iCER4BhjWy4gxJcLQj8rJp2qqR1cU7EFXfzCVdjZhV/kH0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740046186; c=relaxed/simple; bh=Zoo9uQ8Drs94E3LT5wK9nBC48YVNSJ75dwbnTzaoVHw=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=KvCL5FmbSFbd/6yLKcEp/LxzgC8lmo9ugMYyxGTWNKDxWBJ1wuIyRqjy4gGQIuNYRZHasRvqJwM8Qc0E1oKC6t0tmqnUJT8OXyWBjF2bXabeSNKrVLWOPFdqB1u2UNCn8ba4uVQUXKgJVtT2r9Q1DC29oXIsK9Zc6iEl6Puejxw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linaro.org; spf=pass smtp.mailfrom=linaro.org; dkim=pass (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b=TbnxBlwP; arc=none smtp.client-ip=209.85.128.49 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linaro.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linaro.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b="TbnxBlwP" Received: by mail-wm1-f49.google.com with SMTP id 5b1f17b1804b1-43996e95114so4383115e9.3 for ; Thu, 20 Feb 2025 02:09:42 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; t=1740046181; x=1740650981; darn=vger.kernel.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=VKAFazs0bK/4Q6jQNje2L8Expu/NOgNPeCn90wFFS4o=; b=TbnxBlwPjjyp5w4jK7dHSTOLWZ2jty0K7BW6YS3sGDpseukWSP+NfndN8IXkZbspVn y/2hRbyjkA7okR7Npwye0REGht+j8z4kKPj++qi+dFBcIwmBfBx11ZwI93N+aq7BWRY7 4MUHHO+fzvDRFoIqRGAsRaY4GmlMbuvHA/Yx8dxKTVQ744Y/oGu+NlhUmvY9jQOHx6GU XWw5cnlAmw1B2bOx1iRckt9Zla4faaKXtB9VzVCZISstygkJR3MziNB2CaSZT8DsLrQD DwYHFgSgJVm0l/J9lVq4/1wtcJS50Kie/9SNSysy8thpkUl4RigzHFMAVxMnz6xfuVx5 AK+g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1740046181; x=1740650981; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=VKAFazs0bK/4Q6jQNje2L8Expu/NOgNPeCn90wFFS4o=; b=WMnY0OYJQBoluuDJX5U2r1XluBxIzsb+1mpVT4BLbY2GkPdAB3R7g3UciP23Dzr9Wi oiYVfC6LsTjNe5iKnR7rTV/8yWpMgc9Xq6fvXZQOoU5f7lkA5JZSiKTxP/KWPTDtoLLN v1c01tLO+z6PO88XRvTIr54tVvPZK3yONvL5tsmrEgp3GQmkhuf/uZHZSgd3xWkjDBP4 mIWmFjbwaZG0JvZ8bTA6vnetGDc9x6SoORQMI4mlRM/fu6uNi7xX4vkUbvyYZ1tfL1HG bVFTxTsxhM0SpgQyH3J9CXJIWkoPS1hrB+hA/5WguwuELFfF4dIY19IpMPybQ4T51xie qamA== X-Forwarded-Encrypted: i=1; AJvYcCVAPZAWoCMb5vTUEnap4HbJ1loVkUnSoywdHAfL1frKDdT9K3v3b4IgOgkrESQ+wErGpqLE7F9B+0PP@vger.kernel.org X-Gm-Message-State: AOJu0Yw9sHtRLqcJipsRqc4trFahxuaz/ZV3WnJdwLe4tyH/aHnjykvR yPgFj9FSa8uCDLtxEAyKlS+AmFlxVt031iD5EzUUb26VPKKAJFFrrCis1MVJcc8= X-Gm-Gg: ASbGnct7pO6FMaVNdm9wOR16cywoj2xL+Sqg54rnRtqIczlUsazmHkvH0/6vBB8aNH/ JYNyy+G4GWyOPIB2lRgvVV5YZYTb5t8OXwX0Go4CHVqQcAaV+sQT2rdD5U5UWvksyoAUIig0HKx 10si/2BHzEupWng8nzjC5L5T2SOiyoEFK2MXwD/7Ecj6VBd2RdXvvw+DFSxl7TIIOMeub7VVlp3 0qm/8pNYvmTt2eMZ1q6XEMhSvV3f/pmY3rnxPCpAr5Wrc5RWVDyxspAOBC1BbUhkR+b4fMrdAcJ x1ae5/T6TyIW5EQxth9mQAAgfq4= X-Google-Smtp-Source: AGHT+IERc6hIPqaeWn2CPZBGtZZAAoxkqyWFInBWc9QDvWlSHwq2D21AKF4IMfL83X3LHVGKdeB0Yw== X-Received: by 2002:a5d:59a2:0:b0:38d:d9bd:18a6 with SMTP id ffacd0b85a97d-38f33f437fdmr19446268f8f.42.1740046181176; Thu, 20 Feb 2025 02:09:41 -0800 (PST) Received: from linaro.org ([2a02:2454:ff21:ef30:b30c:3d94:4d4a:a6eb]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-38f258b4123sm20741585f8f.17.2025.02.20.02.09.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 20 Feb 2025 02:09:40 -0800 (PST) Date: Thu, 20 Feb 2025 11:09:38 +0100 From: Stephan Gerhold To: Rob Herring Cc: Konrad Dybcio , Vinod Koul , Bjorn Andersson , Konrad Dybcio , Krzysztof Kozlowski , Conor Dooley , Andy Gross , Srinivas Kandagatla , Neil Armstrong , Yuvaraj Ranganathan , Anusha Rao , Md Sadre Alam , linux-arm-msm@vger.kernel.org, dmaengine@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, Luca Weiss Subject: Re: [PATCH 7/8] dt-bindings: dma: qcom: bam-dma: Add missing required properties Message-ID: References: <20250212-bam-dma-fixes-v1-0-f560889e65d8@linaro.org> <20250212-bam-dma-fixes-v1-7-f560889e65d8@linaro.org> <22ce4c8d-1f3b-42c9-b588-b7d74812f7b0@oss.qualcomm.com> <20250219222739.GA3078392-robh@kernel.org> Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250219222739.GA3078392-robh@kernel.org> On Wed, Feb 19, 2025 at 04:27:39PM -0600, Rob Herring wrote: > On Thu, Feb 13, 2025 at 04:22:17PM +0100, Stephan Gerhold wrote: > > On Thu, Feb 13, 2025 at 03:00:00PM +0100, Konrad Dybcio wrote: > > > On 13.02.2025 10:13 AM, Stephan Gerhold wrote: > > > > On Wed, Feb 12, 2025 at 10:01:59PM +0100, Konrad Dybcio wrote: > > > >> On 12.02.2025 6:03 PM, Stephan Gerhold wrote: > > > >>> num-channels and qcom,num-ees are required when there are no clocks > > > >>> specified in the device tree, because we have no reliable way to read them > > > >>> from the hardware registers if we cannot ensure the BAM hardware is up when > > > >>> the device is being probed. > > > >>> > > > >>> This has often been forgotten when adding new SoC device trees, so make > > > >>> this clear by describing this requirement in the schema. > > > >>> > > > >>> Signed-off-by: Stephan Gerhold > > > >>> --- > > > >>> Documentation/devicetree/bindings/dma/qcom,bam-dma.yaml | 4 ++++ > > > >>> 1 file changed, 4 insertions(+) > > > >>> > > > >>> diff --git a/Documentation/devicetree/bindings/dma/qcom,bam-dma.yaml b/Documentation/devicetree/bindings/dma/qcom,bam-dma.yaml > > > >>> index 3ad0d9b1fbc5e4f83dd316d1ad79773c288748ba..5f7e7763615578717651014cfd52745ea2132115 100644 > > > >>> --- a/Documentation/devicetree/bindings/dma/qcom,bam-dma.yaml > > > >>> +++ b/Documentation/devicetree/bindings/dma/qcom,bam-dma.yaml > > > >>> @@ -90,8 +90,12 @@ required: > > > >>> anyOf: > > > >>> - required: > > > >>> - qcom,powered-remotely > > > >>> + - num-channels > > > >>> + - qcom,num-ees > > > >>> - required: > > > >>> - qcom,controlled-remotely > > > >>> + - num-channels > > > >>> + - qcom,num-ees > > > >> > > > >> I think I'd rather see these deprecated and add the clock everywhere.. > > > >> Do we know which one we need to add on newer platforms? Or maybe it's > > > >> been transformed into an icc path? > > > > > > > > This isn't feasible, there are too many different setups. Also often the > > > > BAM power management is tightly integrated into the consumer interface. > > > > To give a short excerpt (I'm sure there are even more obscure uses): > > > > > > > > - BLSP BAM (UART, I2C, SPI on older SoCs): > > > > 1. Enable GCC_BLSP_AHB_CLK > > > > -> This is what the bam_dma driver supports currently. > > > > > > > > - Crypto BAM: Either > > > > OR 1. Vote for single RPM clock > > > > OR 1. Enable 3 separate clocks (CE, CE_AHB, CE_AXI) > > > > OR 1. Vote dummy bandwidth for interconnect > > > > > > > > - BAM DMUX (WWAN on older SoCs): > > > > 1. Start modem firmware > > > > 2. Wait for BAM DMUX service to be up > > > > 3. Vote for power up via the BAM-DMUX-specific SMEM state > > > > 4. Hope the firmware agrees and brings up the BAM > > > > > > > > - SLIMbus BAM (audio on some SoCs): > > > > 1. Start ADSP firmware > > > > 2. Wait for QMI SLIMBUS service to be up via QRTR > > > > 3. Vote for power up via SLIMbus-specific QMI messages > > > > 4. Hope the firmware agrees and brings up the BAM > > > > > > > > Especially for the last two, we can't implement support for those > > > > consumer-specific interfaces in the BAM driver. Implementing support for > > > > the 3 variants of the Crypto BAM would be possible, but it's honestly > > > > the least interesting use case of all these. It's not really clear why > > > > we are bothing with the crypto engine on newer SoCs at all, see e.g. [1]. > > > > > > > > [1]: https://lore.kernel.org/linux-arm-msm/20250118080604.GA721573@sol.localdomain/ > > > > > > > >> Reading back things from this piece of HW only to add it to DT to avoid > > > >> reading it later is a really messy solution. > > > > > > > > In retrospect, it could have been cleaner to avoid describing the BAM as > > > > device node independent of the consumer. We wouldn't have this problem > > > > if the BAM driver would only probe when the consumer is already ready. > > > > > > > > But I think specifying num-channels in the device tree is the cleanest > > > > way out of this mess. I have a second patch series ready that drops > > > > qcom,num-ees and validates the num-channels once it's safe reading from > > > > the BAM registers. That way, you just need one boot test to ensure the > > > > device tree description is really correct. > > > > > > Thanks for the detailed explanation! > > > > > > Do you think it could maybe make sense to expose a clock/power-domain > > > from the modem/adsp rproc and feed it to the DMUX / SLIM instances when > > > an appropriate ping arrives? This way we'd also defer probing the drivers > > > until the device is actually accessible. > > > > > > > Maybe, but that would result in a cyclic dependency between the DMA > > provider and consumer. E.g. > > > > bam_dmux_dma: dma-controller@ { > > #dma-cells = <1>; > > power-domains = <&bam_dmux>; > > }; > > > > remoteproc@ { > > /* ... */ > > > > bam_dmux: bam-dmux { > > dmas = <&bam_dmux_dma 4>, <&bam_dmux_dma 5>; > > dma-names = "tx", "rx"; > > }; > > }; > > > > fw_devlink will likely get confused by that. > > Why? We have a property to break cycles: post-init-providers > > That doesn't work here? > Thanks, I was not aware of that property. This looks quite useful for fixing up some of the other cyclic dependencies we have! Nevertheless, for this specific case, I still think we should not make such large breaking changes at this point. As I pointed out further below in my quoted email, this is a legacy hardware block that will likely not get any major new users in the future. We're essentially discussing to rework several bindings and drivers just to drop a single straightforward "num-channels = " property. A property that we will need to keep support for anyway, to support users with older DTBs. This effort (and risk) is really better spent elsewhere. Thanks, Stephan