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 C20DF18A956; Thu, 8 Aug 2024 12:13:10 +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=1723119190; cv=none; b=AlvwjYAUspkPnKBxtJ9RZ4rLmfU3eQNJevot7yPiIZINRcvc7zVmZLK91flkrFqBEaNFXapnT5zquI3AppCCeJfAMzzgn++Zq485S3gDke0ts5XD/cl7+yWptWoe+iWMeUh39I0D+n8G4E/59SxMf0M66164+8CJCeOKHhBr7co= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723119190; c=relaxed/simple; bh=1ZVqgJ9cbN3pBQ6pyKmkFDwV3heRYL14TRbTr20npLo=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=JrVJ6F9/EFkyvQovUlLCHblxsTbwWgD3L7ARUqRmylso2PIoxo6LMNInuQQRXgnPFCr2cd4tuH1reY1tAqNlbwyQJxi9dOvR2ZMbDZ+rdglBsAWQWcLr9Xi/muL73A32fq0z48w5wD9upV/JsTE88poOmdFowXAYWzcB1GpOSx0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=HCEnbC42; 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="HCEnbC42" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 31317C32782; Thu, 8 Aug 2024 12:13:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1723119190; bh=1ZVqgJ9cbN3pBQ6pyKmkFDwV3heRYL14TRbTr20npLo=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=HCEnbC42iop3o1KuzLxeamRkDT9X9N8k4M0pGMryD88KfzyOGEbRVQzinfJR9T/6M sd7/3sljiGT4WzE2G+NrwHzLaLo5MuKaRh3OLIknqWYUKBOtXx39dbrszCKjRcK2ql jLfCGpi8eR/jvDrCzaqobiEdWqXjkYUMSMZ/tUKYR+ZzyqqRggDs7+Zgw9Vtw/pYQ4 r0wiemI5ByKJgtJgVm/SP6LFk1+CHXuyuedokZG0ObCKmP0E92uu3qBg3ZIYYosU/f pXZ9NqovAgPm9Io8J17f2ZXdd6y3VYMyYFtE/3dcKBnGcRlSlb61OyoZKR1qk2Q3vS dqo9G1UFsdASg== Message-ID: Date: Thu, 8 Aug 2024 14:13:01 +0200 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 v2 1/8] dt-bindings: PCI: Add binding for qps615 To: Manivannan Sadhasivam Cc: Bjorn Andersson , Krishna Chaitanya Chundru , Lorenzo Pieralisi , =?UTF-8?Q?Krzysztof_Wilczy=C5=84ski?= , Rob Herring , Bjorn Helgaas , Krzysztof Kozlowski , Conor Dooley , Konrad Dybcio , cros-qcom-dts-watchers@chromium.org, Bartosz Golaszewski , Jingoo Han , andersson@kernel.org, quic_vbadigan@quicinc.com, linux-arm-msm@vger.kernel.org, linux-pci@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, Bartosz Golaszewski References: <20240803-qps615-v2-0-9560b7c71369@quicinc.com> <20240803-qps615-v2-1-9560b7c71369@quicinc.com> <5f65905c-f1e4-4f52-ba7c-10c1a4892e30@kernel.org> <90582c92-ca50-4776-918d-b7486cf942b0@kernel.org> <20240808120109.GA18983@thinkpad> From: Krzysztof Kozlowski Content-Language: en-US Autocrypt: addr=krzk@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 08/08/2024 14:01, Manivannan Sadhasivam wrote: > On Mon, Aug 05, 2024 at 07:18:04PM +0200, Krzysztof Kozlowski wrote: >> On 05/08/2024 19:07, Bjorn Andersson wrote: >>> On Mon, Aug 05, 2024 at 09:41:26AM +0530, Krishna Chaitanya Chundru wrote: >>>> On 8/4/2024 2:23 PM, Krzysztof Kozlowski wrote: >>>>> On 03/08/2024 05:22, Krishna chaitanya chundru wrote: >>>>>> diff --git a/Documentation/devicetree/bindings/pci/qcom,qps615.yaml b/Documentation/devicetree/bindings/pci/qcom,qps615.yaml >>> [..] >>>>>> + qps615,axi-clk-freq-hz: >>>>>> + description: >>>>>> + AXI clock which internal bus of the switch. >>>>> >>>>> No need, use CCF. >>>>> >>>> ack >>> >>> This is a clock that's internal to the QPS615, so there's no clock >>> controller involved and hence I don't think CCF is applicable. >> >> AXI does not sound that internal. > > Well, AXI is applicable to whatever entity that implements it. We mostly seen it > in ARM SoCs (host), but in this case the PCIe switch also has a microcontroller > /processor of some sort, so AXI is indeed relevant for it. The naming actually > comes from the switch's i2c register name that is being configured in the driver > based on this property value. > >> DT rarely needs to specify internal >> clock rates. What if you want to define rates for 20 clocks? Even >> clock-frequency is deprecated, so why this would be allowed? >> bus-frequency is allowed for buses, but that's not the case here, I guess? >> > > This clock frequency is for the switch's internal AXI bus that runs at default > 200MHz. And this property is used to specify a frequency that is configured over > the i2c interface so that the switch's AXI bus can operate in a low frequency > there by reducing the power consumption of the switch. > > It is not strictly needed for the switch operation, but for power optimization. > So this property can also be dropped for the initial submission and added later > if you prefer. So if the clock rate can change, why this is static in DTB? Or why this is configurable per-board? There is a reason why clock-frequency property is not welcomed and you are re-implementing it. Best regards, Krzysztof