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 4BBF9197A68; Mon, 24 Mar 2025 09:07:30 +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=1742807251; cv=none; b=DgUNb+RJFKgou3cI3i2pOnEM0pTBVPefbe3mbPy9EW9aTxUPW1ddOnsmu2SmhKXWwZHabpbB+sM6iE6xjPNNkUKLJ83ycnxmi2Q+/LYGVlishU7v9X2Dr8XqfJ3p1VzOqOWusFWXMDySVCUAS0DL1CylDLwW2NkWQNhQEgwltlI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742807251; c=relaxed/simple; bh=BTpr/xKyMbID/mfk2G3kaCpevUKnRtaW+ey2UsAOI6E=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=fbu6VRCCglxUNQxTPmJHPSdBXj2EIqzEeTgllH1oZYu6uqVJdgW+qRVRa1Lpy3xbVRYb8eLA3sCJpIZUppScePOUzGvKTB/MMb6pZ3TrXZrXLu+2BYnnY5gPpG1nx/PKXaNfTbLHzJ2wv2fItQNouHbwMtWYwWzxOs1ygGFIoyU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=f0OB4Pb3; 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="f0OB4Pb3" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8BBA4C4CEDD; Mon, 24 Mar 2025 09:07:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1742807250; bh=BTpr/xKyMbID/mfk2G3kaCpevUKnRtaW+ey2UsAOI6E=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=f0OB4Pb35nUhcXZhCBCSRewAqNK2Xhvrgmdwb/9fVpgDIdnh0125n1W4E86MdNuMb ZBXHQkB4GDy2fOQQ6FA14iRWHAA+pQMvKqM5K/r7MKt58z3k+GcL4K13VI2h1n9kPZ XXu/MPKHJXdGg12NcHSPzjHa5KOvHLujIg1BVSFTdEN61Tmjg9gYLuiMxRblRpxRhP KkQ6pCBpk3raDNs6lgBuS3w3hq4vUJGq4aO9ueIJN24l5aAq/YqxB6Jk+HJh25Nj+H LqtPJj6gH01xJSybftNaqwKHdmeLBWVVA20wH0RInTb6d+yVGfKKVi2rSYDBIZkbqm L76iINlYXna2g== Message-ID: <4523caea-3406-4de0-9ab5-424fb7a0a474@kernel.org> Date: Mon, 24 Mar 2025 10:07:21 +0100 Precedence: bulk X-Mailing-List: linux-i2c@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v16 1/3] dt-bindings: i2c: aspeed: support for AST2600-i2cv2 To: Ryan Chen Cc: "benh@kernel.crashing.org" , "joel@jms.id.au" , "andi.shyti@kernel.org" , "robh@kernel.org" , "krzk+dt@kernel.org" , "conor+dt@kernel.org" , "andrew@codeconstruct.com.au" , "p.zabel@pengutronix.de" , "andriy.shevchenko@linux.intel.com" , "linux-i2c@vger.kernel.org" , "openbmc@lists.ozlabs.org" , "devicetree@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linux-aspeed@lists.ozlabs.org" , "linux-kernel@vger.kernel.org" , Mo Elbadry References: <20250224055936.1804279-1-ryan_chen@aspeedtech.com> <20250224055936.1804279-2-ryan_chen@aspeedtech.com> <20250224-arrogant-adventurous-mackerel-0dc18a@krzk-bin> <50327725-f3b8-4a8b-94a2-85afccd2868a@kernel.org> <069b9fe4-c54a-4efd-923e-1558c59fe3f4@kernel.org> <677cb075-24ae-45d8-bfb4-9b23fbacc5df@kernel.org> <994cb954-f3c4-4a44-800e-9303787c1be9@kernel.org> From: Krzysztof Kozlowski Content-Language: en-US Autocrypt: addr=krzk@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 24/03/2025 09:30, Ryan Chen wrote: >> Subject: Re: [PATCH v16 1/3] dt-bindings: i2c: aspeed: support for >> AST2600-i2cv2 >> >> On 19/03/2025 12:12, Ryan Chen wrote: >>>> Subject: Re: [PATCH v16 1/3] dt-bindings: i2c: aspeed: support for >>>> AST2600-i2cv2 >>>> >>>> On 17/03/2025 10:21, Ryan Chen wrote: >>>>>> Neither this. >>>>>> >>>>>> So it seems you describe already existing and documented I2C, but >>>>>> for some reason you want second compatible. The problem is that you >>>>>> do not provide reason from the point of view of bindings. >>>>>> >>>>>> To summarize: what your users want - don't care. Start properly >>>>>> describing hardware and your SoC. >>>>> >>>>> OK, for ast2600 i2c controller have two register mode setting. >>>>> One, I call it is old register setting, that is right now >>>>> i2c-aspeed.c .compatible = "aspeed,ast2600-i2c-bus", And there have >>>>> a global register >>>> that can set i2c controller as new mode register set. >>>>> That I am going to drive. That I post is all register in new an old register >> list. >>>>> >>>>> For example, >>>>> Global register [2] = 0 => i2c present as old register set Global >>>>> register [2] = 1 => i2c present as new register set >>>> It's the same device though, so the same compatible. >>> >>> Sorry, it is different design, and it share the same register space. >>> So that the reason add new compatible "aspeed,ast2600-i2cv2" for this >> driver. >>> It is different register layout. >> >> Which device is described by the existing "aspeed,ast2600-i2c-bus" >> compatible? And which device is described by new compatible? >> > On the AST2600 SoC, there are up to 16 I2C controller instances (I2C1 ~ I2C16). So you have 16 same devices. > Each of these controllers is hardwired at the SoC level to use either the legacy register layout or the new v2 register layout. > The mode is selected by a bit in the global register, these represent two different hardware blocks: > "aspeed,ast2600-i2c-bus" describes controllers using the legacy register layout. > "aspeed,ast2600-i2cv2" describes controllers using the new register layout Which part of "same device" is not clear? You have one device, one compatible. Whatever you do with register layout, is already defined by that compatible. It does not matter that you forgot to implement it in the Linux kernel. Best regards, Krzysztof