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[91.67.66.34]) by smtp.gmail.com with ESMTPSA id gj10-20020a170907740a00b00726c0e63b94sm2547537ejc.27.2022.07.15.17.24.50 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Fri, 15 Jul 2022 17:24:50 -0700 (PDT) Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3696.100.31\)) Subject: Re: [PATCH v4] arm64: dts: rockchip: Fix SD card init on rk3399-nanopi4 From: =?utf-8?Q?Christian_Kohlsch=C3=BCtter?= In-Reply-To: Date: Sat, 16 Jul 2022 02:24:49 +0200 Cc: wens@kernel.org, =?utf-8?Q?Heiko_St=C3=BCbner?= , Markus Reichl , linux-arm-kernel , "open list:ARM/Rockchip SoC..." , linux-kernel , Linux MMC List Content-Transfer-Encoding: quoted-printable Message-Id: <3912A668-9F73-40FD-8993-5060F632238A@kohlschutter.com> References: <12878108.O9o76ZdvQC@diego> <103b714c-b07c-f016-1062-84bd94786b22@arm.com> <9AF1E75F-5947-49B0-887D-82C426527B99@kohlschutter.com> <590f7a08-a6ca-be54-4254-363343642a52@arm.com> <5ca9bd94-54d9-04f8-0098-a56ffb6f5fe1@arm.com> <502b3fbe-3077-407e-6010-a8cb3ffce7d6@arm.com> <449292CA-CE60-4B90-90F7-295FBFEAB3F8@kohlschutter.com> <73F9AED0-D2A8-4294-B6E1-1B92D2A36529@kohlschutter.com> <115AD6A4-021B-4879-BFB5-BC7689A0203E@kohlschutter.com> <17a4c6f6-d79c-a7b2-860f-e5944b778f9f@arm.com> <9405b97a-6758-ad4e-ccff-eed072096539@arm.com> To: Robin Murphy X-Mailer: Apple Mail (2.3696.100.31) Precedence: bulk List-ID: X-Mailing-List: linux-mmc@vger.kernel.org >>=20 >>> There may well be another bug slumbering in the codebase that is = circumvented by 1. adding a delay in the code and 2. not turning the = regulator off upon shutdown. >>=20 >> Yes, it seems suboptimal that the regulator core allows this glitch = where an always-on regulator which is already on gets turned off at all, = but I guess that's its own problem. In the meantime, off-on-delay-us = sounds like the most likely property to bandage this locally. I'm seeing = a fall time in the order of milliseconds (attached), so we'd probably = want a fair chunk of that to be safe. >>=20 >> Robin. >=20 > I think we have a way where there's no need to pick a delay value that = may ultimately not work in all cases. > Following up with "[PATCH] regulator: core: Resolve supply name = earlier to prevent double-init" [1] >=20 > Thank you so much for helping me getting that far! It would be great = if you'd keep following the thread. >=20 > Best, > Christian >=20 > [1] https://www.spinics.net/lists/kernel/msg4440365.html @Robin, oddly enough, setting off-on-delay-us with values of up to a second = (1000000 us) still results in failed inits. I hope we can find another bandage until the regular-core patch gets = merged.