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Tue, 1 Oct 2024 09:24:37 +0000 (GMT) Received: from epsmgms1p1new.samsung.com (unknown [182.195.42.41]) by epsmtrp1.samsung.com (KnoxPortal) with ESMTP id 20241001092437epsmtrp144171194025493dde8b4dd0f78c40c98~6SepFV66K2044120441epsmtrp1K; Tue, 1 Oct 2024 09:24:37 +0000 (GMT) X-AuditID: b6c32a4b-23fff70000002648-36-66fbc036f9b0 Received: from epsmtip2.samsung.com ( [182.195.34.31]) by epsmgms1p1new.samsung.com (Symantec Messaging Gateway) with SMTP id 2D.B2.08229.5DFBBF66; Tue, 1 Oct 2024 18:24:37 +0900 (KST) Received: from FDSFTE196 (unknown [107.116.189.214]) by epsmtip2.samsung.com (KnoxPortal) with ESMTPA id 20241001092435epsmtip2a711f1c09bcaa3ec1ef771a9d53a1818~6SenhES3P1396013960epsmtip2_; Tue, 1 Oct 2024 09:24:35 +0000 (GMT) From: "Inbaraj E" To: "'Krzysztof Kozlowski'" , "'Stephen Boyd'" , , , , , , , Cc: , In-Reply-To: <1c6c56f7-bdda-4e14-9910-80e0cda0d631@kernel.org> Subject: RE: [PATCH] clk: samsung: fsd: Mark PLL_CAM_CSI as critical Date: Tue, 1 Oct 2024 14:54:34 +0530 Message-ID: <03ca01db13e3$bc12e360$3438aa20$@samsung.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Mailer: Microsoft Outlook 16.0 Thread-Index: AQMYu0UT7KgXFJ9p8WqzYl/+4ytJPAKVNCMjAc9ECZkCVSVjTgGurbUsAUVIpqkCfYGRoa+U+ARQ Content-Language: en-in X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFlrBJsWRmVeSWpSXmKPExsWy7bCmlq7Zgd9pBpO6uC0ezNvGZnH9y3NW i5sHdjJZnD+/gd3iY889VovLu+awWcw4v4/J4uIpV4tFW7+wWxx+085q8e/aRhYHbo/3N1rZ PTat6mTz6NuyitHj8ya5AJaobJuM1MSU1CKF1Lzk/JTMvHRbJe/geOd4UzMDQ11DSwtzJYW8 xNxUWyUXnwBdt8wcoKOUFMoSc0qBQgGJxcVK+nY2RfmlJakKGfnFJbZKqQUpOQUmBXrFibnF pXnpenmpJVaGBgZGpkCFCdkZl99NZS/YaVCx9e9p5gbGXo0uRk4OCQETibVbjjN3MXJxCAns ZpR4u/AHE4TziVHi25vfjBDON0aJyc96GGFaHk+dzg5iCwnsZZRo+yMIUfQSqP1ECxNIgk1A U+Lm0X9g3SICS5kkOu/9AOtgFjCT2HL3PmsXIwcHp4CdxOFNgiBhYQEXiRn/LjGD2CwCKhLX f0Es4BWwlHjzcD0LhC0ocXLmExaIMdoSyxa+ZoY4SEHi59NlrCC2iECUxILTG9kgasQljv7s AftNQmAth8SEzc/YQPZKAC3r2KYC0Sss8er4FnYIW0riZX8blO0jsX/OL6iHMySObV/OCmHb Sxy4MocFZAwz0I/rd+lDhGUlpp5axwSxlk+i9/cTJog4r8SOeTC2ssTMI/fZIGxJiZ2Xd7JM YFSaheSzWUg+m4Xkg1kI2xYwsqxilEwtKM5NTy02LTDOSy2Hx3dyfu4mRnCS1fLewfjowQe9 Q4xMHIyHGCU4mJVEeO8d+pkmxJuSWFmVWpQfX1Sak1p8iNEUGNwTmaVEk/OBaT6vJN7QxNLA xMzMzMTS2MxQSZz3devcFCGB9MSS1OzU1ILUIpg+Jg5OqQYmWdn37o0uMv6sTN/4g33O9T5g uzVvr9KvX/KP1sRWNyqk6lTZHXlp5bbdr8xpW5GBSdP73XvWy2jbTzBpldDi2+dx73Y8d7Hk dLYMUz+z1Isp+3MvtjdsLrm5ybYjeNuWkuLFZ7+XaKuvVFj0i5er4NOvDaWBKnzMSlu2dy+9 yspqd1zxzu5VNSEyRzdm/DKYetJ16cLUPp6DvEYHLwdtUX7duuJS+bv1SROsJ3oqdTotKdAV 3Z8Sop6dlqgksvhZhk8X/4RFz/4dXtnvPM3z3YkrelF3w/3KVnetmrx2QeKc/hg7cfnbhc1X zBQDl8fJTopXPjktbqqI2RKeEw4Gt47PCmr/zHHizqn2k7xKLMUZiYZazEXFiQDJzxhGOwQA AA== X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFprAIsWRmVeSWpSXmKPExsWy7bCSvO7V/b/TDF5fl7d4MG8bm8X1L89Z LW4e2Mlkcf78BnaLjz33WC0u75rDZjHj/D4mi4unXC0Wbf3CbnH4TTurxb9rG1kcuD3e32hl 99i0qpPNo2/LKkaPz5vkAliiuGxSUnMyy1KL9O0SuDJm31vFWHBAv6J/8gnmBsY29S5GTg4J AROJx1Ons3cxcnEICexmlFi5/jYrREJSYvZvkASILSyx8t9zMFtI4DmjxIuVVSA2m4CmxM2j /xhBmkUE1jJJdGxfyQiSYBawkFj+5zobREMDs8SNZ+VdjBwcnAJ2Eoc3CYKEhQVcJGb8u8QM YrMIqEhc/wWxi1fAUuLNw/UsELagxMmZT1ggRmpL9D5sZYSxly18zQxxm4LEz6fLwG4WEYiS WHB6IxtEjbjE0Z89zBMYhWchGTULyahZSEbNQtKygJFlFaNkakFxbnpusWGBYV5quV5xYm5x aV66XnJ+7iZGcKRpae5g3L7qg94hRiYOxkOMEhzMSiK89w79TBPiTUmsrEotyo8vKs1JLT7E KM3BoiTOK/6iN0VIID2xJDU7NbUgtQgmy8TBKdXAdPBG743lvjt0/n5z+sptWfPvNut5luhb vQFRfge3KN96/O5+hq5E2IPDZ8r0rmfO0jvOEiPEuEf01SblOcpuu3eG7LX+bHf7UywP//2p /nnzTu0Ovjzt35rJfLdmpDNfsL+95e77uTJZM3wWGS++tWH7+dSvoevOsTKKTdnK+9jyjPMu oY9irgEX50gEXua+3b1JNeRWZdGzQ27Ps8tMy5uP7WNXz58/TbfsJ8/RuAdbBasc718Qed5g e3y5iKlbvP5UDeM+hrdBElxXimJOl7UGSy/qqdec/YB7+/6aNWc+3JrZoidc+0bp2YzWlp7N iUKRqx2fLN/Z4XnYp+fgDM4XjFf/9FzN5/DKtt++YYISS3FGoqEWc1FxIgAYZuEZIwMAAA== X-CMS-MailID: 20241001092437epcas5p220d68d2b7aeeda4f766e4c83c7c9e79a X-Msg-Generator: CA Content-Type: text/plain; charset="utf-8" X-Sendblock-Type: REQ_APPROVE CMS-TYPE: 105P DLP-Filter: Pass X-CFilter-Loop: Reflected X-CMS-RootMailID: 20240917101102epcas5p3b17d2774cb74fd4cf61ea52fde85c300 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> > -----Original Message----- > From: Krzysztof Kozlowski > Sent: 20 September 2024 18:07 > To: Inbaraj E ; 'Stephen Boyd' > ; alim.akhtar=40samsung.com; cw00.choi=40samsung.com; > linux-clk=40vger.kernel.org; linux-kernel=40vger.kernel.org; linux-samsun= g- > soc=40vger.kernel.org; mturquette=40baylibre.com; s.nawrocki=40samsung.co= m > Cc: pankaj.dubey=40samsung.com; gost.dev=40samsung.com > Subject: Re: =5BPATCH=5D clk: samsung: fsd: Mark PLL_CAM_CSI as critical >=20 > On 20/09/2024 06:15, Inbaraj E wrote: > > > > > >> -----Original Message----- > >> From: Inbaraj E > >> Sent: 20 September 2024 09:35 > >> To: 'Krzysztof Kozlowski' ; 'Stephen Boyd' > >> ; 'alim.akhtar=40samsung.com' > >> ; 'cw00.choi=40samsung.com' > >> ; 'linux-clk=40vger.kernel.org' >> clk=40vger.kernel.org>; 'linux-kernel=40vger.kernel.org' >> kernel=40vger.kernel.org>; 'linux-samsung-soc=40vger.kernel.org' >> samsung-soc=40vger.kernel.org>; 'mturquette=40baylibre.com' > >> ; 's.nawrocki=40samsung.com' > >> > >> Cc: 'pankaj.dubey=40samsung.com' ; > >> 'gost.dev=40samsung.com' > >> Subject: RE: =5BPATCH=5D clk: samsung: fsd: Mark PLL_CAM_CSI as critic= al > >> > >> > >> > >>> -----Original Message----- > >>> From: Krzysztof Kozlowski > >>> Sent: 19 September 2024 17:33 > >>> To: Inbaraj E ; 'Stephen Boyd' > >>> ; alim.akhtar=40samsung.com; > >> cw00.choi=40samsung.com; > >>> linux-clk=40vger.kernel.org; linux-kernel=40vger.kernel.org; > >>> linux-samsung- soc=40vger.kernel.org; mturquette=40baylibre.com; > >>> s.nawrocki=40samsung.com > >>> Cc: pankaj.dubey=40samsung.com; gost.dev=40samsung.com > >>> Subject: Re: =5BPATCH=5D clk: samsung: fsd: Mark PLL_CAM_CSI as criti= cal > >>> > >>> On 19/09/2024 13:33, Inbaraj E wrote: > >>>> > >>>> > >>>>> -----Original Message----- > >>>>> From: Stephen Boyd > >>>>> Sent: 19 September 2024 15:51 > >>>>> To: Inbaraj E ; alim.akhtar=40samsung.com; > >>>>> cw00.choi=40samsung.com; krzk=40kernel.org; linux- > clk=40vger.kernel.org; > >>>>> linux- kernel=40vger.kernel.org; linux-samsung-soc=40vger.kernel.or= g; > >>>>> mturquette=40baylibre.com; s.nawrocki=40samsung.com > >>>>> Cc: pankaj.dubey=40samsung.com; gost.dev=40samsung.com; Inbaraj E > >>>>> > >>>>> Subject: Re: =5BPATCH=5D clk: samsung: fsd: Mark PLL_CAM_CSI as > >>>>> critical > >>>>> > >>>>> Quoting Inbaraj E (2024-09-17 03:10:16) > >>>>>> PLL_CAM_CSI is the parent clock for the ACLK and PCLK in the > >>>>>> CMU_CAM_CSI block. When we gate ACLK or PCLK, the clock > >> framework > >>>>> will > >>>>>> subsequently disables the parent clocks(PLL_CAM_CSI). Disabling > >>>>>> PLL_CAM_CSI is causing sytem level halt. > >>>>>> > >>>>>> It was observed on FSD SoC, when we gate the ACLK and PCLK > during > >>>>>> CSI stop streaming through pm_runtime_put system is getting > halted. > >>>>>> So marking PLL_CAM_CSI as critical to prevent disabling. > >>>>>> > >>>>>> Signed-off-by: Inbaraj E > >>>>>> --- > >>>>> > >>>>> Please add a fixes tag. Although this is likely a band-aid fix > >>>>> because marking something critical leaves it enabled forever. > >>>> > >>>> Sure, will add fixes tag. As per HW manual, this PLL_CAM_CSI is > >>>> supplying clock even for CMU SFR access of CSI block, so we can't > >>>> gate this. > >>> > >>> Hm, I am not so sure. The CMU driver should just take appropriate clo= ck. > >>> Sprinkling CLK_CRITICAL looks as substitute of missing clock > >>> handling/ > >> > >> As per HW design, PLL_CAM_CSI is responsible for suppling clock to > >> CSI SFR, CMU SFR and some internal block of CAM_CSI. In this some of > >> the clock is not handled by any driver but it is required for CSI to > >> work properly. For example CSI NOC clock. So this is the reason we are > marking PLL_CAM_CSI as critical. > >> > > > > This is clock hierarchy for CMU_CAM_CSI block. > > > > PLL_CAM_CSI -----> DIVIDER --------> CSI_SFR clock > > =7C > > =7C----> DIVIDER --------> CMU_SFR clock > > =7C > > =7C----> DIVIDER --------> CSI NOC clock. > > >=20 > And what is the problem in adding proper handling in the driver? You just > described case valid for 99% of SoC components. Hi Kryzstof, Sorry, but it seems I was not able to explain the issue. Let me add more details: So for CSI IP we have two clocks as ACLK and PCLK which needs to be handled by the driver during start and stop streaming.=20 In BLK_CSI we have CSI IP along with other bunch supporting modules such as CMU_CSI, NOC_CSI, CSI_SFR. For all these components of BLK_CSI we have a single top level parent PLL clock as PLL_CAM_CSI.=20 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=20 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.=20 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 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.=20 Please let us know if you have any other queries why we are insisting on marking PLL_CAM_CSI as CRITICAL clock. Regards, Inbaraj E >=20 > Best regards, > Krzysztof