From 55841199050d0c6c44eb7f24717816e6e372599f Mon Sep 17 00:00:00 2001 From: Douglas Anderson Date: Wed, 24 Aug 2022 14:22:56 -0700 Subject: [PATCH] regulator: core: Require regulator drivers to check uV for get_optimum_mode() The get_optimum_mode() for regulator drivers is passed the input voltage and output voltage as well as the current. This is because, in theory, the optimum mode can depend on all three things. It turns out that for all regulator drivers in mainline only the current is looked at when implementing get_optimum_mode(). None of the drivers take the input or output voltage into account. Despite the fact that none of the drivers take the input or output voltage into account, though, the regulator framework will error out before calling into get_optimum_mode() if it doesn't know the input or output voltage. The above behavior turned out to be a probelm for some boards when we landed commit efb0cb50c427 ("regulator: qcom-rpmh: Implement get_optimum_mode(), not set_load()"). Before that change we'd have no problems running drms_uA_update() for RPMH regulators even if a regulator's input or output voltage was unknown. After that change drms_uA_update() started to fail. This is because typically boards using RPMH regulators don't model the input supplies of RPMH regulators. Input supplies for RPMH regulators nearly always come from the output of other RPMH regulators (or always-on regulators) and RPMH firmware is initialized with this knowledge and handles enabling (and adjusting the voltage of) input supplies. While we could model the parent/child relationship of the regulators in Linux, many boards don't bother since it adds extra overhead. Let's change the regulator core to make things work again. Now if we fail to get the input or output voltage we'll still call into get_optimum_mode() and we'll just pass error codes in for input_uV and/or output_uV parameters. Since no existing regulator drivers even look at input_uV and output_uV we don't need to add this error handling anywhere right now. We'll add some comments in the core so that it's obvious that (if regulator drivers care) it's up to them to add the checks. Reported-by: Andrew Halaney Fixes: efb0cb50c427 ("regulator: qcom-rpmh: Implement get_optimum_mode(), not set_load()") Signed-off-by: Douglas Anderson Tested-by: Andrew Halaney Link: https://lore.kernel.org/r/20220824142229.RFT.v2.1.I137e6bef4f6d517be7b081be926059321102fd3d@changeid Signed-off-by: Mark Brown --- drivers/regulator/core.c | 22 ++++++++++++++-------- 1 file changed, 14 insertions(+), 8 deletions(-) diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c index 18fa920..fd8582d 100644 --- a/drivers/regulator/core.c +++ b/drivers/regulator/core.c @@ -979,10 +979,13 @@ static int drms_uA_update(struct regulator_dev *rdev) } else { /* get output voltage */ output_uV = regulator_get_voltage_rdev(rdev); - if (output_uV <= 0) { - rdev_err(rdev, "invalid output voltage found\n"); - return -EINVAL; - } + + /* + * Don't return an error; if regulator driver cares about + * output_uV then it's up to the driver to validate. + */ + if (output_uV <= 0) + rdev_dbg(rdev, "invalid output voltage found\n"); /* get input voltage */ input_uV = 0; @@ -990,10 +993,13 @@ static int drms_uA_update(struct regulator_dev *rdev) input_uV = regulator_get_voltage(rdev->supply); if (input_uV <= 0) input_uV = rdev->constraints->input_uV; - if (input_uV <= 0) { - rdev_err(rdev, "invalid input voltage found\n"); - return -EINVAL; - } + + /* + * Don't return an error; if regulator driver cares about + * input_uV then it's up to the driver to validate. + */ + if (input_uV <= 0) + rdev_dbg(rdev, "invalid input voltage found\n"); /* now get the optimum mode for our new total regulator load */ mode = rdev->desc->ops->get_optimum_mode(rdev, input_uV, -- 2.7.4