kernel/drivers/platform/x86/intel_scu_ipc.c, branch linux-6.9.y

platform/x86: intel_scu_ipc: Fail IPC send if still busy

2023-09-18T13:15:15Z

It's possible for interrupts to get significantly delayed to the point that callers of intel_scu_ipc_dev_command() and friends can call the function once, hit a timeout, and call it again while the interrupt still hasn't been processed. This driver will get seriously confused if the interrupt is finally processed after the second IPC has been sent with ipc_command(). It won't know which IPC has been completed. This could be quite disastrous if calling code assumes something has happened upon return from intel_scu_ipc_dev_simple_command() when it actually hasn't. Let's avoid this scenario by simply returning -EBUSY in this case. Hopefully higher layers will know to back off or fail gracefully when this happens. It's all highly unlikely anyway, but it's better to be correct here as we have no way to know which IPC the status register is telling us about if we send a second IPC while the previous IPC is still processing. Cc: Prashant Malani Cc: Kuppuswamy Sathyanarayanan Reviewed-by: Andy Shevchenko Reviewed-by: Mika Westerberg Fixes: ed12f295bfd5 ("ipc: Added support for IPC interrupt mode") Signed-off-by: Stephen Boyd Link: https://lore.kernel.org/r/20230913212723.3055315-5-swboyd@chromium.org Reviewed-by: Ilpo Järvinen Reviewed-by: Hans de Goede Signed-off-by: Hans de Goede

platform/x86: intel_scu_ipc: Don't override scu in intel_scu_ipc_dev_simple_command()

2023-09-18T13:15:02Z

Andy discovered this bug during patch review. The 'scu' argument to this function shouldn't be overridden by the function itself. It doesn't make any sense. Looking at the commit history, we see that commit f57fa18583f5 ("platform/x86: intel_scu_ipc: Introduce new SCU IPC API") removed the setting of the scu to ipcdev in other functions, but not this one. That was an oversight. Remove this line so that we stop overriding the scu instance that is used by this function. Reported-by: Andy Shevchenko Closes: https://lore.kernel.org/r/ZPjdZ3xNmBEBvNiS@smile.fi.intel.com Cc: Prashant Malani Reviewed-by: Andy Shevchenko Reviewed-by: Mika Westerberg Fixes: f57fa18583f5 ("platform/x86: intel_scu_ipc: Introduce new SCU IPC API") Signed-off-by: Stephen Boyd Link: https://lore.kernel.org/r/20230913212723.3055315-4-swboyd@chromium.org Reviewed-by: Ilpo Järvinen Reviewed-by: Hans de Goede Signed-off-by: Hans de Goede

platform/x86: intel_scu_ipc: Check status upon timeout in ipc_wait_for_interrupt()

2023-09-18T13:14:53Z

It's possible for the completion in ipc_wait_for_interrupt() to timeout, simply because the interrupt was delayed in being processed. A timeout in itself is not an error. This driver should check the status register upon a timeout to ensure that scheduling or interrupt processing delays don't affect the outcome of the IPC return value. CPU0 SCU ---- --- ipc_wait_for_interrupt() wait_for_completion_timeout(&scu->cmd_complete) [TIMEOUT] status[IPC_STATUS_BUSY]=0 Fix this problem by reading the status bit in all cases, regardless of the timeout. If the completion times out, we'll assume the problem was that the IPC_STATUS_BUSY bit was still set, but if the status bit is cleared in the meantime we know that we hit some scheduling delay and we should just check the error bit. Cc: Prashant Malani Reviewed-by: Kuppuswamy Sathyanarayanan Reviewed-by: Andy Shevchenko Reviewed-by: Mika Westerberg Fixes: ed12f295bfd5 ("ipc: Added support for IPC interrupt mode") Signed-off-by: Stephen Boyd Link: https://lore.kernel.org/r/20230913212723.3055315-3-swboyd@chromium.org Reviewed-by: Hans de Goede Signed-off-by: Hans de Goede

platform/x86: intel_scu_ipc: Check status after timeout in busy_loop()

2023-09-18T13:14:22Z

It's possible for the polling loop in busy_loop() to get scheduled away for a long time. status = ipc_read_status(scu); // status = IPC_STATUS_BUSY if (!(status & IPC_STATUS_BUSY)) If this happens, then the status bit could change while the task is scheduled away and this function would never read the status again after timing out. Instead, the function will return -ETIMEDOUT when it's possible that scheduling didn't work out and the status bit was cleared. Bit polling code should always check the bit being polled one more time after the timeout in case this happens. Fix this by reading the status once more after the while loop breaks. The readl_poll_timeout() macro implements all of this, and it is shorter, so use that macro here to consolidate code and fix this. There were some concerns with using readl_poll_timeout() because it uses timekeeping, and timekeeping isn't running early on or during the late stages of system suspend or early stages of system resume, but an audit of the code concluded that this code isn't called during those times so it is safe to use the macro. Cc: Prashant Malani Reviewed-by: Andy Shevchenko Reviewed-by: Mika Westerberg Reviewed-by: Kuppuswamy Sathyanarayanan Fixes: e7b7ab3847c9 ("platform/x86: intel_scu_ipc: Sleeping is fine when polling") Signed-off-by: Stephen Boyd Link: https://lore.kernel.org/r/20230913212723.3055315-2-swboyd@chromium.org Reviewed-by: Ilpo Järvinen Reviewed-by: Hans de Goede Signed-off-by: Hans de Goede

drivers: remove struct module * setting from struct class

2023-03-17T14:16:27Z

There is no need to manually set the owner of a struct class, as the registering function does it automatically, so remove all of the explicit settings from various drivers that did so as it is unneeded. This allows us to remove this pointer entirely from this structure going forward. Cc: "Rafael J. Wysocki" Link: https://lore.kernel.org/r/20230313181843.1207845-2-gregkh@linuxfoundation.org Signed-off-by: Greg Kroah-Hartman

platform/x86: intel_scu_ipc: fix possible name leak in __intel_scu_ipc_register()

2022-12-08T16:35:49Z

In some error paths before device_register(), the names allocated by dev_set_name() are not freed. Move dev_set_name() front to device_register(), so the name can be freed while calling put_device(). Fixes: 54b34aa0a729 ("platform/x86: intel_scu_ipc: Split out SCU IPC functionality from the SCU driver") Signed-off-by: Yang Yingliang Link: https://lore.kernel.org/r/20221208151916.2404977-1-yangyingliang@huawei.com Reviewed-by: Hans de Goede Signed-off-by: Hans de Goede

platform/x86: intel_scu_ipc: Update timeout value in comment

2021-10-11T13:34:51Z

The comment decribing the IPC timeout hadn't been updated when the actual timeout was changed from 3 to 5 seconds in commit a7d53dbbc70a ("platform/x86: intel_scu_ipc: Increase virtual timeout from 3 to 5 seconds") . Since the value is anyway updated to 10s now, take this opportunity to update the value in the comment too. Signed-off-by: Prashant Malani Cc: Benson Leung Reviewed-by: Mika Westerberg Link: https://lore.kernel.org/r/20210928101932.2543937-4-pmalani@chromium.org Signed-off-by: Hans de Goede

platform/x86: intel_scu_ipc: Increase virtual timeout to 10s

2021-10-11T13:34:45Z

Commit a7d53dbbc70a ("platform/x86: intel_scu_ipc: Increase virtual timeout from 3 to 5 seconds") states that the recommended timeout range is 5-10 seconds. Adjust the timeout value to the higher of those i.e 10 seconds, to account for situations where the 5 seconds is insufficient for disconnect command success. Signed-off-by: Prashant Malani Cc: Benson Leung Reviewed-by: Mika Westerberg Link: https://lore.kernel.org/r/20210928101932.2543937-3-pmalani@chromium.org Signed-off-by: Hans de Goede

platform/x86: intel_scu_ipc: Fix busy loop expiry time

2021-10-11T13:34:39Z

The macro IPC_TIMEOUT is already in jiffies (it is also used like that elsewhere in the file when calling wait_for_completion_timeout()). Don’t convert it using helper functions for the purposes of calculating the busy loop expiry time. Fixes: e7b7ab3847c9 (“platform/x86: intel_scu_ipc: Sleeping is fine when polling”) Signed-off-by: Prashant Malani Cc: Benson Leung Reviewed-by: Mika Westerberg Link: https://lore.kernel.org/r/20210928101932.2543937-2-pmalani@chromium.org Signed-off-by: Hans de Goede

platform/x86: intel_scu_ipc: Fix doc of intel_scu_ipc_dev_command_with_size()

2021-08-20T18:00:02Z

The kernel doc validator complains: .../ipc.c:478: warning: expecting prototype for intel_scu_ipc_command_with_size(). Prototype was for intel_scu_ipc_dev_command_with_size() instead Fix the prototype name in the kernel documentation. Reported-by: kernel test robot Signed-off-by: Andy Shevchenko Link: https://lore.kernel.org/r/20210820110458.73018-2-andriy.shevchenko@linux.intel.com Signed-off-by: Hans de Goede