From: Huisong Li lihuisong@huawei.com
[ Upstream commit 91cefefb699120efd0a5ba345d12626b688f86ce ]
Currently, the function waiting for completion of mailbox operation is 'wait_for_completion()'. The PCC method will be permanently blocked if this mailbox message fails to execute. So this patch replaces it with 'wait_for_completion_timeout()'. And set the timeout interval to an arbitrary retries on top of nominal to prevent the remote processor is slow to respond to PCC commands.
Fixes: 77e2a04745ff ("ACPI: PCC: Implement OperationRegion handler for the PCC Type 3 subtype") Signed-off-by: Huisong Li lihuisong@huawei.com Reviewed-by: Sudeep Holla sudeep.holla@arm.com Signed-off-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/acpi/acpi_pcc.c | 23 +++++++++++++++++++++-- 1 file changed, 21 insertions(+), 2 deletions(-)
diff --git a/drivers/acpi/acpi_pcc.c b/drivers/acpi/acpi_pcc.c index 84f1ac416b57..16ba875e3293 100644 --- a/drivers/acpi/acpi_pcc.c +++ b/drivers/acpi/acpi_pcc.c @@ -23,6 +23,12 @@
#include <acpi/pcc.h>
+/* + * Arbitrary retries in case the remote processor is slow to respond + * to PCC commands + */ +#define PCC_CMD_WAIT_RETRIES_NUM 500 + struct pcc_data { struct pcc_mbox_chan *pcc_chan; void __iomem *pcc_comm_addr; @@ -89,6 +95,7 @@ acpi_pcc_address_space_handler(u32 function, acpi_physical_address addr, { int ret; struct pcc_data *data = region_context; + u64 usecs_lat;
reinit_completion(&data->done);
@@ -99,8 +106,20 @@ acpi_pcc_address_space_handler(u32 function, acpi_physical_address addr, if (ret < 0) return AE_ERROR;
- if (data->pcc_chan->mchan->mbox->txdone_irq) - wait_for_completion(&data->done); + if (data->pcc_chan->mchan->mbox->txdone_irq) { + /* + * pcc_chan->latency is just a Nominal value. In reality the remote + * processor could be much slower to reply. So add an arbitrary + * amount of wait on top of Nominal. + */ + usecs_lat = PCC_CMD_WAIT_RETRIES_NUM * data->pcc_chan->latency; + ret = wait_for_completion_timeout(&data->done, + usecs_to_jiffies(usecs_lat)); + if (ret == 0) { + pr_err("PCC command executed timeout!\n"); + return AE_TIME; + } + }
mbox_client_txdone(data->pcc_chan->mchan, ret);