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 006471E376F; Mon, 21 Oct 2024 09:51:03 +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=1729504264; cv=none; b=s8ZNaGun2Y8Dzc49THjXVqwdDVoO04+KyaU/MuIVDYaMnmHyVaNuetTDLUbaGLy2kqTi3Sc6RtLnSpzgkqjSVQ5+r+FlAl+AXwnKF9iMNqTlnaniAHVPv+5gQGsbhMrmlzz3SDulNijwV3srx0ec3BaJKjGzRudBu+j1McqWTkg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729504264; c=relaxed/simple; bh=X09WrzGaODsmNxi4MZUA10RHzluSaOG9VjS7+1qrpMQ=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=CcJI0gbk8jGbo/MKpTlPq4dTJ+rc16zwL/S+HLMhn8qSjplacpusdJ+Cw4cyjkWx5tAVQfF8kcX1fnmLY3XR8Soo4jvTWsSbqfqQfR+gEoBbg7q4haoVifjk3gkCiJeykj6rQLfyeG7DXGkPswTsiudo7o1Chyh0SJYD+JjVe9U= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=JHYEo0d5; 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="JHYEo0d5" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7BCEAC4CEE5; Mon, 21 Oct 2024 09:51:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1729504263; bh=X09WrzGaODsmNxi4MZUA10RHzluSaOG9VjS7+1qrpMQ=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=JHYEo0d5RBJSQzYVDBixw1G5aM9qjoSrsn+EAPW2Od38FXWsFyTagP97ArwK4nehI wgpMjlXN1ztJxTkKSnLEsC4WQfNwWktvtQI3ON7BE+wobvejo3eMFR8YQMFGAXWqCg SW9dpNY3eCNWCny7SAJ3Iic/3yk1UPy6a9elw3hUTf/G0yYyt0G8VtRD8CRT/Jmo/k 6Pq/9IXcNWBVL751DRM8wqgEmol0bBgYClQpyCPuAzAXWOGbHRVg7m9FocnmeCPjog v/d3kgdGPRi7OfdG7uAR8/3f7cNDbleZqiXdVkG+Gf0DRK30vR8fiSixakfP+mXbnd o2umvzuUfVvBg== Message-ID: <6f090ce4-fa29-40c5-8959-b57d135b3a31@kernel.org> Date: Mon, 21 Oct 2024 11:50:57 +0200 Precedence: bulk X-Mailing-List: linux-clk@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] clk: samsung: fsd: Mark PLL_CAM_CSI as critical To: Inbaraj E , 'Stephen Boyd' , alim.akhtar@samsung.com, cw00.choi@samsung.com, linux-clk@vger.kernel.org, linux-kernel@vger.kernel.org, linux-samsung-soc@vger.kernel.org, mturquette@baylibre.com, s.nawrocki@samsung.com Cc: pankaj.dubey@samsung.com, gost.dev@samsung.com References: <20240917101016.23238-1-inbaraj.e@samsung.com> <0d43a00985a815c1869ebc6c441a2aed.sboyd@kernel.org> <00f001db0a87$cd9ddfa0$68d99ee0$@samsung.com> <633ff284-101d-4651-833e-a6b01626c9a1@kernel.org> <011401db0b13$cbd045f0$6370d1d0$@samsung.com> <1c6c56f7-bdda-4e14-9910-80e0cda0d631@kernel.org> <03ca01db13e3$bc12e360$3438aa20$@samsung.com> <2b3566dd-71ac-4ef7-abdc-524277879aa6@kernel.org> <08d001db1b01$94a9b9f0$bdfd2dd0$@samsung.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 10/10/2024 12:45, Inbaraj E wrote: >>> Now if we look into CSI driver perspective it needs only ACLK and PCLK >>> clocks for it's operations. But to access CMU SFRs (including >>> ACLK/PCLK or any other CMU SFR of BLK_CSI) we need parent clock keep >>> supplying clocks. While we try to gate ACLK clock, due to propagation >>> logic of clock gating the CCF scans all the clocks from leaf level to >>> the parent clock and tries to gate clocks if enable/disable ops is >>> valid for any such clock. >>> >>> Issue here is that we are trying to gate PLL_CAM_CSI which itself is >>> accessible only when this clock is enabled. In fact none of CMU_SFR >>> will be accessible as soon as PLL_CAM_CSI is gated. CSI driver is not >>> intended >> >> Obviously, but your CMU is taking the necessary clock and enabled it so what >> is the problem? >> >>> to gate this PLL clock but only the leaf level clock which is >>> supplying to CSI IP. So in absence of any alternate source of clock >>> hierarchy which can supply clock for CMU_CSI we can't gate PLL_CAM_CSI. >>> >>> Please let us know if you have any other queries why we are insisting >>> on marking PLL_CAM_CSI as CRITICAL clock. >> >> This is so far quite obvious - just like in all other cases, you need the top clock >> taken by proper driver. I don't think you are looking at right drivers and right >> problem here. >> > > Hi Krzysztof, > > In this case, platform driver need to get this PLL clock and keep it > enabled always. As PLL_CAM_CSI is source clock for accessing CMU > registers of CSI block, and PLL_CAM_CSI itself lies in CSI_CMU, > driver need to prepare and keep it enabled always. This way other PCLK > and ACLK clocks can be gated. But the PLL_CAM_CSI which is parent of the > PCLK and ACLK gate clock won't be disabled. Hope this should not be a > concern. > Yes, that's expected. It properly models the hierarchy and consumers of clocks, while keeping something as critical does not model the consumers. Best regards, Krzysztof