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Fri, 5 Jun 2020 06:37:29 +0000 (GMT) From: Marek Szyprowski To: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, Mark Brown , Dmitry Osipenko Cc: Marek Szyprowski , Liam Girdwood , Lucas Stach , Bartlomiej Zolnierkiewicz , Krzysztof Kozlowski , Viresh Kumar , peron.clem@gmail.com, Nishanth Menon , Stephen Boyd , Vincent Guittot , Rafael Wysocki , linux-samsung-soc@vger.kernel.org, Chanwoo Choi Subject: [PATCH] regulator: do not balance 'boot-on' coupled regulators without constraints Date: Fri, 5 Jun 2020 08:37:24 +0200 Message-Id: <20200605063724.9030-1-m.szyprowski@samsung.com> X-Mailer: git-send-email 2.17.1 X-Brightmail-Tracker: H4sIAAAAAAAAA0VSa0hTYRju2zlnO0qr4xR8s9AcdCcvGfRBIhkVh8iI6k+i1srT1Lyx47X+ aEat1ZxamYwyyR/GbKljmUlZmqW5dF7SZmlkmqVpUuqwm+U8y/6973PheV54aUJWSXnRsYkp nCpRES8Xu5LVz763bVz/qTcq4Mu0L64qqqDwlYEhMX419ZHC5V8HEbZaKyX43fVeEba/VItw V+01MZ7UNiJcZK0TYWNjvwSPzbSK8JviLhK/sHRSeLanisTqRjuBq6bZbW7sfX2/hDUZzovZ vp4HYlb3O4A1d58j2VyzAbFNtnsidtLkvY8Odw2O5uJj0ziVf8gR15jLj0pR8gxkDOi+ibLQ jIcGudDAbIbTdVZKg1xpGXMLwVihjhCWKQTP6o2ksEwiKBm4gP5ZbnwwOIkyBO3NJmrBkq3L lThUYiYQNOMasYPwYLIR3C1pFzkIgvlJwMMOX8fszkRCo32ccswkswpayobmNVImGOwlfyRC nA+UVz6eLwVMtQQ+6gudxA4YNvcTwuwOo01mJ74CLJcukoIhB8FAm1EiLBcRdJ0ucl6xFfra fsz1o+cqrYOKWn8BDoWnV4zzMDBLwDbuJpReAgXVVwkBloL6rExQrwZ9052F2Pr2TmcdFnJf n5kPks3d+F6tJvOQt/5/VglCBuTJpfIJSo4PSuTS/XhFAp+aqPQ7lpRgQnN/ZJltmq5Bdb+O NiCGRvLFUluHLUpGKdL4zIQGBDQh95Bub7VEyaTRisyTnCrpsCo1nuMb0HKalHtKg26ORMoY pSKFO8FxyZzqHyuiXbyyEIzG+ZT71nRrldmL4oqWHk8dGb+Vu7b99m4zTPkcXKltPWTYM1rm GbCl067f23DmVY5XXsQTbUtV6KNTVuPS/SbNhvzi2fCdeW4hw/k/+LCw7olBKgMimyfYz77P V79dpssP31Q6FBNqsY6s0X05UJ4dvWtxsjbCv8CWF6n08kmXk3yMInA9oeIVfwHfu+mtQwMA AA== X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFmpjkeLIzCtJLcpLzFFi42I5/e/4PV3NFzfjDA4/NbfYOGM9q8XUh0/Y LK5/ec5qsfrjY0aL8+c3sFs8mHuTyeLblQ4mi8u75rBZfO49wmgx4/w+Jou1R+6yW7z5cZbJ 4va8yywWZ05fYrX4d20ji0XHkW/MFhu/ejgIeuycdZfdY9OqTjaPO9f2sHn0/zXw2HK1ncWj b8sqRo/jN7YzeXzeJBfAEaVnU5RfWpKqkJFfXGKrFG1oYaRnaGmhZ2RiqWdobB5rZWSqpG9n k5Kak1mWWqRvl6CXMWX/YsaCHxIVD/s/MTUw/hDpYuTkkBAwkZj/dBVLFyMXh5DAUkaJnadX MEEkZCROTmtghbCFJf5c62KDKPrEKLFu2j6wIjYBQ4mutxAJEYFWRonzr1cxgTjMAq0sEgvu rGIGqRIWiJZ4uHMdC4jNIqAqcWr5E7BuXgEbiW8L/rNDrJCXWL3hAPMERp4FjAyrGEVSS4tz 03OLjfSKE3OLS/PS9ZLzczcxAuNg27GfW3Ywdr0LPsQowMGoxMN74+KNOCHWxLLiytxDjBIc zEoivE5nT8cJ8aYkVlalFuXHF5XmpBYfYjQFWj6RWUo0OR8Yo3kl8YamhuYWlobmxubGZhZK 4rwdAgdjhATSE0tSs1NTC1KLYPqYODilGhhPCbJ5GBun7vZ5rDF7/UcPc6PDFv4G11a/DJjQ /jvksNRLg2mZZ9/Uz+oUXHBq6kuh5e3cEcHHE2oC/yxh+8mb37YpNlBQkOtv/GPBKi/d7PBP 4c07OD58y2kzcRO5OClNzP//4Q+79+jVT6tri3084/GMHpWu7SbbTs+23BVhINRzOzi656YS S3FGoqEWc1FxIgBd1QSsmQIAAA== X-CMS-MailID: 20200605063729eucas1p288dd9d3acdb62cc86745cb6af5c31fc6 X-Msg-Generator: CA X-RootMTR: 20200605063729eucas1p288dd9d3acdb62cc86745cb6af5c31fc6 X-EPHeader: CA CMS-TYPE: 201P X-CMS-RootMailID: 20200605063729eucas1p288dd9d3acdb62cc86745cb6af5c31fc6 References: Sender: linux-samsung-soc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-samsung-soc@vger.kernel.org Balancing of the 'boot-on' coupled regulators must wait until the clients set their constraints, otherwise the balancing code might change the voltage of the not-yet-constrained regulator to the value below the bootloader-configured operation point, what might cause a system crash. This is achieved by assuming that, the minimal voltage allowed for the given 'boot-on' regulator is equal to it's current voltage until consumers apply their constraints. Suggested-by: Dmitry Osipenko Signed-off-by: Marek Szyprowski --- This is yet another approach to fix the regulator coupling on Exynos5800/5422 SoCs in the regulator core. I agree with Dmitry that this issue is generic and if possible it should be handled in the core. This patchset is another attempt to fix the regulator coupling on Exynos5800/5422 SoCs. Here are links to the previous attempts and discussions: https://lore.kernel.org/linux-samsung-soc/20191008101709.qVNy8eijBi0LynOteWFMnTg4GUwKG599n6OyYoX1Abs@z/ https://lore.kernel.org/lkml/20191017102758.8104-1-m.szyprowski@samsung.com/ https://lore.kernel.org/linux-pm/cover.1589528491.git.viresh.kumar@linaro.org/ https://lore.kernel.org/linux-pm/20200528131130.17984-1-m.szyprowski@samsung.com/ https://lore.kernel.org/linux-samsung-soc/57cf3a15-5d9b-7636-4c69-60742e8cfae6@samsung.com/ The problem is with "vdd_int" regulator coupled with "vdd_arm" on Odroid XU3/XU4 boards family. "vdd_arm" is handled by CPUfreq. "vdd_int" is handled by devfreq. CPUfreq initialized quite early during boot and it starts changing OPPs and "vdd_arm" value. Sometimes CPU activity during boot goes down and some low-frequency OPPs are selected, what in turn causes lowering "vdd_arm". This happens before devfreq applies its requirements on "vdd_int". Regulator balancing code reduces "vdd_arm" voltage value, what in turn causes lowering "vdd_int" value to the lowest possible value. This is much below the operation point of the wcore bus, which still runs at the highest frequency. The issue was hard to notice because in the most cases the board managed to boot properly, even when the regulator was set to lowest value allowed by the regulator constraints. However, it caused some random issues, which can be observed as "Unhandled prefetch abort" or low USB stability. Best regards Marek Szyprowski --- drivers/regulator/core.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c index 03154f5b939f..7e9af7ea4bdf 100644 --- a/drivers/regulator/core.c +++ b/drivers/regulator/core.c @@ -3553,6 +3553,17 @@ static int regulator_get_optimal_voltage(struct regulator_dev *rdev, if (ret < 0) return ret; + /* + * If no constraints set yet and regulator has boot-on flag, + * keep its voltage unchanged + */ + if (tmp_min == 0 && c_rdevs[i]->constraints->boot_on) { + ret = regulator_get_voltage_rdev(c_rdevs[i]); + if (ret < 0) + return ret; + tmp_min = ret; + } + ret = regulator_check_voltage(c_rdevs[i], &tmp_min, &tmp_max); if (ret < 0) return ret;