From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.ozlabs.org (gandalf.ozlabs.org [150.107.74.76]) (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 591A42E6114; Thu, 11 Sep 2025 09:03:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=150.107.74.76 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757581430; cv=none; b=hoUuej1x/uMOxq05yLNNcHUupjWE5oQhuk1Ckz7EVzpZu7LrvifbtoEOFPgS6ehvJ2lT8aLCM/i3GhWEMDQwcFW9UCwrLMa/+YmSj2JvcaBTL5Cz1GUT6UNI5scJ0cwiSgowxbjknupox/5FuM6V0oBLjTuOcheTmhH80A44T1Q= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757581430; c=relaxed/simple; bh=MXAroO2Vgv/Aw4+0pF/V1BNZSWRlBJi9ioA+EBy/UUI=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=Q2ZOOUzdNANOgPrpKywcW0V7enI8JNws0Q37gwl+u4wjoCy0zOPqVzjVKzrQ3d75k9syXkic0Up5qxChw+CYkq+oY11m1pojkz1z32TLzQvQ8rawyy/RtFHzmjLPiYqDUMJsDH4+KzIF+TKqUy9d7Y5Ifqi+HKh4Wv4NmfRunMw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=ozlabs.org; spf=pass smtp.mailfrom=ozlabs.org; dkim=pass (2048-bit key) header.d=ozlabs.org header.i=@ozlabs.org header.b=eC7I0Sd8; arc=none smtp.client-ip=150.107.74.76 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=ozlabs.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=ozlabs.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=ozlabs.org header.i=@ozlabs.org header.b="eC7I0Sd8" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ozlabs.org; s=201707; t=1757581425; bh=9jGcvOJ/2zIoXs3jwzmzA+R7eyYFP6KicLp4LvaH6+s=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=eC7I0Sd8DAcvARRMk7gSLhQfnmUYQpLWw0SxQbapw03i3+CqDJ3UVERzC74tH33Dy Ev7bCORrnoI/zq+uiGhuXWrvVHwT5E/MtrfoUVD2NxCklYAXuEZTXDodeHN1XazLlu 4sQZlAZzfCLkwaW3cXZhRKqE5zLOwUfXqILuCVRQEGGPq+WE5xqzeDjqCvAqQxSsIH BF1JxnA1xoFgifHbGydZIM7AEO2as8uTEF7IMa+pcQrzxjHmIfw7G6TcwSYL1U0F+g M2RNjT0NsWWdJNdhKrwwXrVihmPPk1a5WhHTay4pLIFUxPqgEXYFpSR4Uc2r8vWnXU nLrlVqMRqY35Q== Received: from authenticated.ozlabs.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by mail.ozlabs.org (Postfix) with ESMTPSA id 4cMs6l4WjPz4wB0; Thu, 11 Sep 2025 19:03:43 +1000 (AEST) Message-ID: Subject: Re: [PATCH v16 1/3] dt-bindings: i2c: aspeed: support for AST2600-i2cv2 From: Jeremy Kerr To: Ryan Chen , Krzysztof Kozlowski Cc: "robh@kernel.org" , "conor+dt@kernel.org" , "andriy.shevchenko@linux.intel.com" , "andi.shyti@kernel.org" , "linux-aspeed@lists.ozlabs.org" , "devicetree@vger.kernel.org" , "openbmc@lists.ozlabs.org" , Mo Elbadry , "linux-kernel@vger.kernel.org" , "joel@jms.id.au" , "p.zabel@pengutronix.de" , "krzk+dt@kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linux-i2c@vger.kernel.org" Date: Thu, 11 Sep 2025 17:03:39 +0800 In-Reply-To: <3fdee5330d91b5d18a69a311e4df6de874973ced.camel@ozlabs.org> References: <20250224055936.1804279-1-ryan_chen@aspeedtech.com> <069b9fe4-c54a-4efd-923e-1558c59fe3f4@kernel.org> <677cb075-24ae-45d8-bfb4-9b23fbacc5df@kernel.org> <994cb954-f3c4-4a44-800e-9303787c1be9@kernel.org> <4523caea-3406-4de0-9ab5-424fb7a0a474@kernel.org> <8e8aa069-af9f-453f-9bd0-e3dc2eab59ab@kernel.org> <99053328-a117-493e-b5f3-00902669c8e7@kernel.org> <44ef5c93448a3625fcfd003b47a516e8ba795b62.camel@ozlabs.org> <52943e49aaea7bb6def5bc51dfd57392b6ae66e4.camel@ozlabs.org> <3fdee5330d91b5d18a69a311e4df6de874973ced.camel@ozlabs.org> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.46.4-2 Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Hi all, After a bit of a chat with Ryan, some updates on this: > The question was more: it sounds like you're switching between > *fundamentally different* hardware units with the mux switch - not just > a different register interface for the same peripheral hardware. Is that > the case? Turns out: no. The controller core is the same, but what gets muxed in/out is more of a compatibility interface. This provides an ast2500-like register set to the ast2600 i2c peripheral. So, the plan to use the same aspeed,ast2600-i2c-bus binding for the controllers (ie, as in v18) seems mostly sensible to me. The newly-introduced driver can make use of the non-compat interface to the peripheral (using the existing compatible value), but needs the introduction of support for the global register set to do so. Ideally, this would have been included on the original spec for the aspeed,ast2600-i2c-bus binding (since that's how the hardware is laid out), but that wasn't the case. We may want to split the aspeed,ast2600-i2c-bus binding out from the existing spec, as we currently have: compatible: enum: - aspeed,ast2400-i2c-bus - aspeed,ast2500-i2c-bus - aspeed,ast2600-i2c-bus - but the former two do not have a global register-set. We may have better syscon-like options for handling that global register set, but that's more of a conversation for the v18 thread. Cheers, Jeremy