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[91.67.66.34]) by smtp.gmail.com with ESMTPSA id 17-20020a170906211100b0072b2378027csm220357ejt.26.2022.08.04.03.44.30 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Thu, 04 Aug 2022 03:44:30 -0700 (PDT) Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3696.120.41.1.1\)) Subject: [PATCH v3] regulator: core: Resolve supply name earlier to prevent double-init From: =?utf-8?Q?Christian_Kohlsch=C3=BCtter?= In-Reply-To: Date: Thu, 4 Aug 2022 12:44:29 +0200 Cc: =?utf-8?Q?Heiko_St=C3=BCbner?= , Liam Girdwood , linux-arm-kernel , linux-kernel , Linux MMC List , "open list:ARM/Rockchip SoC..." , Markus Reichl , Robin Murphy , wens@kernel.org Content-Transfer-Encoding: quoted-printable Message-Id: References: To: Vincent Legoll , Mark Brown X-Mailer: Apple Mail (2.3696.120.41.1.1) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Previously, an unresolved regulator supply reference upon calling regulator_register on an always-on or boot-on regulator caused set_machine_constraints to be called twice. This in turn may initialize the regulator twice, leading to voltage glitches that are timing-dependent. A simple, unrelated configuration change may be enough to hide this problem, only to be surfaced by chance. One such example is the SD-Card voltage regulator in a NanoPI R4S that would not initialize reliably unless the registration flow was just complex enough to allow the regulator to properly reset between calls. Fix this by re-arranging regulator_register, trying resolve the regulator's supply early enough that set_machine_constraints does not need to be called twice. Signed-off-by: Christian Kohlsch=3DC3=3DBCtter --- drivers/regulator/core.c | 51 +++++++++++++++++++++++++--------------- 1 file changed, 32 insertions(+), 19 deletions(-) diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c index 398c8d6afd4..5c2b97ea633 100644 --- a/drivers/regulator/core.c +++ b/drivers/regulator/core.c @@ -5492,7 +5492,38 @@ regulator_register(const struct regulator_desc =3D *regulator_desc, BLOCKING_INIT_NOTIFIER_HEAD(&rdev->notifier); INIT_DELAYED_WORK(&rdev->disable_work, regulator_disable_work); =3D20 - /* preform any regulator specific init */ + /* set regulator constraints */ + if (init_data) + rdev->constraints =3D3D kmemdup(&init_data->constraints, + sizeof(*rdev->constraints), + GFP_KERNEL); + else + rdev->constraints =3D3D =3D kzalloc(sizeof(*rdev->constraints), + GFP_KERNEL); + if (!rdev->constraints) { + ret =3D3D -ENOMEM; + goto clean; + } + + if (init_data && init_data->supply_regulator) + rdev->supply_name =3D3D init_data->supply_regulator; + else if (regulator_desc->supply_name) + rdev->supply_name =3D3D regulator_desc->supply_name; + + if ((rdev->supply_name && !rdev->supply) && rdev->constraints + && (rdev->constraints->always_on || =3D rdev->constraints->boot_on)) { + /* Try to resolve the name of the supplying regulator =3D here first + * so we prevent double-initializing the regulator, =3D which may + * cause timing-specific voltage brownouts/glitches that =3D are + * hard to debug. + */ + ret =3D3D regulator_resolve_supply(rdev); + if (ret) + rdev_dbg(rdev, "unable to resolve supply early: =3D %pe\n", + ERR_PTR(ret)); + } + + /* perform any regulator specific init */ if (init_data && init_data->regulator_init) { ret =3D3D init_data->regulator_init(rdev->reg_data); if (ret < 0) @@ -5518,24 +5549,6 @@ regulator_register(const struct regulator_desc =3D *regulator_desc, (unsigned long) atomic_inc_return(®ulator_no)); dev_set_drvdata(&rdev->dev, rdev); =3D20 - /* set regulator constraints */ - if (init_data) - rdev->constraints =3D3D kmemdup(&init_data->constraints, - sizeof(*rdev->constraints), - GFP_KERNEL); - else - rdev->constraints =3D3D =3D kzalloc(sizeof(*rdev->constraints), - GFP_KERNEL); - if (!rdev->constraints) { - ret =3D3D -ENOMEM; - goto wash; - } - - if (init_data && init_data->supply_regulator) - rdev->supply_name =3D3D init_data->supply_regulator; - else if (regulator_desc->supply_name) - rdev->supply_name =3D3D regulator_desc->supply_name; - ret =3D3D set_machine_constraints(rdev); if (ret =3D3D=3D3D -EPROBE_DEFER) { /* Regulator might be in bypass mode and so needs its =3D supply --=3D20 2.36.2