From 427fada620733e6474d783ae6037a66eae42bf8c Mon Sep 17 00:00:00 2001
From: Stephen Boyd <swboyd@chromium.org>
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 <pmalani@chromium.org>
Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Fixes: ed12f295bfd5 ("ipc: Added support for IPC interrupt mode")
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
Link: https://lore.kernel.org/r/20230913212723.3055315-3-swboyd@chromium.org
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
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 4c774ee8bb1bb..299c15312acb8 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;
--
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