| Message ID | 20181222202623.4521-3-wsa+renesas@sang-engineering.com (mailing list archive) |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
| Series | i2c: move handling of suspended adapters to the core | expand |
Hi, Thank you for this new version. On 22-12-18 21:26, Wolfram Sang wrote: > Using the 'is_suspended' flag from the PM core, we now reject new > transfers if the parent of the adapter is already marked suspended. I've been running some tests and I'm afraid that those have exposed multiple issues: 1) It seems that adap->dev.parent can be NULL in some cases, specifically this patch causes the i915 driver to crash during probe on an Apollo Lake laptop with an eDP panel. I've attached a fixup patch which fixes this. 2) There are multiple suspend stages: prepare suspend, suspend_late, suspend_no_irq and several devices which need access to i2c-transfers suspend from the suspend_late or even the suspend_no_irq handler. The way this works is that first all devices are moved to the prepared state, then a second run is done moving all devices over to suspended, then a third run moving all devices over to suspend_late, etc. To make this work, e.g. the i2c-designware driver has a nop suspend callback and does the actual suspend from its suspend_late or suspend_no_irq callback. But the is_suspended flag we are testing for now gets set during the suspend phase. So when we are then asked to do an i2c-transfer during the suspend_late phase we get a false-positive triggering of the: if (WARN(device_is_suspended(adap->dev.parent), "Accessing already suspended I2C/SMBus adapter")) return -ESHUTDOWN; WARN and a return of -ESHUTDOWN, because the adapter is in the suspended state, but it has not actually been suspended / moved to the D3 low-power state as that happens later when we reach e.g. the suspend_no_irq phase of the suspend. This is not only a problem with the somewhat complex PMIC situation on some Cherry Trail devices, but it also breaks the i915 driver since as a PCI device the i915 device also only really gets turned off from the suspend_no_irq phase of the suspend. Sorry, this is something which I should have realized before, but well I didn't. TL;DR: really only the adapter driver knows when the device is put in such a state that it can no longer do transfers, as it actually turns of clks / moves it D3 / etc. Which may happen at any of the 3 suspend phases so any "core" based solution is going to get this wrong. I share your desire to have the check for this shared in core code, but I'm afraid that just is not going to work. Regards, Hans > Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com> > --- > Documentation/i2c/fault-codes | 4 ++++ > drivers/i2c/i2c-core-base.c | 3 +++ > drivers/i2c/i2c-core-smbus.c | 4 ++++ > 3 files changed, 11 insertions(+) > > diff --git a/Documentation/i2c/fault-codes b/Documentation/i2c/fault-codes > index 47c25abb7d52..0cee0fc545b4 100644 > --- a/Documentation/i2c/fault-codes > +++ b/Documentation/i2c/fault-codes > @@ -112,6 +112,10 @@ EPROTO > case is when the length of an SMBus block data response > (from the SMBus slave) is outside the range 1-32 bytes. > > +ESHUTDOWN > + Returned when a transfer was requested using an adapter > + which is already suspended. > + > ETIMEDOUT > This is returned by drivers when an operation took too much > time, and was aborted before it completed. > diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c > index 28460f6a60cc..3ce238b782f3 100644 > --- a/drivers/i2c/i2c-core-base.c > +++ b/drivers/i2c/i2c-core-base.c > @@ -1865,6 +1865,9 @@ int __i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num) > > if (WARN_ON(!msgs || num < 1)) > return -EINVAL; > + if (WARN(device_is_suspended(adap->dev.parent), > + "Accessing already suspended I2C/SMBus adapter")) > + return -ESHUTDOWN; > > if (adap->quirks && i2c_check_for_quirks(adap, msgs, num)) > return -EOPNOTSUPP; > diff --git a/drivers/i2c/i2c-core-smbus.c b/drivers/i2c/i2c-core-smbus.c > index 9cd66cabb84f..e0f7f22feabd 100644 > --- a/drivers/i2c/i2c-core-smbus.c > +++ b/drivers/i2c/i2c-core-smbus.c > @@ -547,6 +547,10 @@ s32 __i2c_smbus_xfer(struct i2c_adapter *adapter, u16 addr, > int try; > s32 res; > > + if (WARN(device_is_suspended(adapter->dev.parent), > + "Accessing already suspended I2C/SMBus adapter")) > + return -ESHUTDOWN; > + > /* If enabled, the following two tracepoints are conditional on > * read_write and protocol. > */ > From 0ff431b48f7f2d08bbf299265c67589a598ec5d4 Mon Sep 17 00:00:00 2001 From: Hans de Goede <hdegoede@redhat.com> Date: Mon, 24 Dec 2018 22:00:31 +0100 Subject: [PATCH] FIXUP: i2c: reject new transfers when adapters are suspended Signed-off-by: Hans de Goede <hdegoede@redhat.com> --- drivers/i2c/i2c-core-base.c | 2 +- drivers/i2c/i2c-core-smbus.c | 3 ++- 2 files changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c index 3ce238b782f3..e2fae7ec6c95 100644 --- a/drivers/i2c/i2c-core-base.c +++ b/drivers/i2c/i2c-core-base.c @@ -1865,7 +1865,7 @@ int __i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num) if (WARN_ON(!msgs || num < 1)) return -EINVAL; - if (WARN(device_is_suspended(adap->dev.parent), + if (WARN(adap->dev.parent && device_is_suspended(adap->dev.parent), "Accessing already suspended I2C/SMBus adapter")) return -ESHUTDOWN; diff --git a/drivers/i2c/i2c-core-smbus.c b/drivers/i2c/i2c-core-smbus.c index e0f7f22feabd..1376620ae204 100644 --- a/drivers/i2c/i2c-core-smbus.c +++ b/drivers/i2c/i2c-core-smbus.c @@ -547,7 +547,8 @@ s32 __i2c_smbus_xfer(struct i2c_adapter *adapter, u16 addr, int try; s32 res; - if (WARN(device_is_suspended(adapter->dev.parent), + if (WARN(adapter->dev.parent && + device_is_suspended(adapter->dev.parent), "Accessing already suspended I2C/SMBus adapter")) return -ESHUTDOWN;
> I share your desire to have the check for this shared in core code, > but I'm afraid that just is not going to work. Okay, so this series is definately not it. Probably the previous one which exposes helpers is not a bad idea after all. Because it is ulitmately the driver's decision when to use the helpers...
Hi, On 03-01-19 19:59, Wolfram Sang wrote: > >> I share your desire to have the check for this shared in core code, >> but I'm afraid that just is not going to work. > > Okay, so this series is definately not it. Probably the previous one > which exposes helpers is not a bad idea after all. Because it is > ulitmately the driver's decision when to use the helpers... Agreed. Regards, Hans
diff --git a/Documentation/i2c/fault-codes b/Documentation/i2c/fault-codes index 47c25abb7d52..0cee0fc545b4 100644 --- a/Documentation/i2c/fault-codes +++ b/Documentation/i2c/fault-codes @@ -112,6 +112,10 @@ EPROTO case is when the length of an SMBus block data response (from the SMBus slave) is outside the range 1-32 bytes. +ESHUTDOWN + Returned when a transfer was requested using an adapter + which is already suspended. + ETIMEDOUT This is returned by drivers when an operation took too much time, and was aborted before it completed. diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c index 28460f6a60cc..3ce238b782f3 100644 --- a/drivers/i2c/i2c-core-base.c +++ b/drivers/i2c/i2c-core-base.c @@ -1865,6 +1865,9 @@ int __i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num) if (WARN_ON(!msgs || num < 1)) return -EINVAL; + if (WARN(device_is_suspended(adap->dev.parent), + "Accessing already suspended I2C/SMBus adapter")) + return -ESHUTDOWN; if (adap->quirks && i2c_check_for_quirks(adap, msgs, num)) return -EOPNOTSUPP; diff --git a/drivers/i2c/i2c-core-smbus.c b/drivers/i2c/i2c-core-smbus.c index 9cd66cabb84f..e0f7f22feabd 100644 --- a/drivers/i2c/i2c-core-smbus.c +++ b/drivers/i2c/i2c-core-smbus.c @@ -547,6 +547,10 @@ s32 __i2c_smbus_xfer(struct i2c_adapter *adapter, u16 addr, int try; s32 res; + if (WARN(device_is_suspended(adapter->dev.parent), + "Accessing already suspended I2C/SMBus adapter")) + return -ESHUTDOWN; + /* If enabled, the following two tracepoints are conditional on * read_write and protocol. */
Using the 'is_suspended' flag from the PM core, we now reject new transfers if the parent of the adapter is already marked suspended. Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com> --- Documentation/i2c/fault-codes | 4 ++++ drivers/i2c/i2c-core-base.c | 3 +++ drivers/i2c/i2c-core-smbus.c | 4 ++++ 3 files changed, 11 insertions(+)