From 427fada620733e6474d783ae6037a66eae42bf8c Mon Sep 17 00:00:00 2001 From: Stephen Boyd Date: Wed, 13 Sep 2023 14:27:20 -0700 Subject: [PATCH] platform/x86: intel_scu_ipc: Check status upon timeout in ipc_wait_for_interrupt() 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 --- drivers/platform/x86/intel_scu_ipc.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/platform/x86/intel_scu_ipc.c b/drivers/platform/x86/intel_scu_ipc.c index 4c774ee..299c153 100644 --- a/drivers/platform/x86/intel_scu_ipc.c +++ b/drivers/platform/x86/intel_scu_ipc.c @@ -248,10 +248,12 @@ static inline int ipc_wait_for_interrupt(struct intel_scu_ipc_dev *scu) { int status; - if (!wait_for_completion_timeout(&scu->cmd_complete, IPC_TIMEOUT)) - return -ETIMEDOUT; + wait_for_completion_timeout(&scu->cmd_complete, IPC_TIMEOUT); status = ipc_read_status(scu); + if (status & IPC_STATUS_BUSY) + return -ETIMEDOUT; + if (status & IPC_STATUS_ERR) return -EIO; -- 2.7.4