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platform/x86: intel_scu_ipc: Sleeping is fine when polling

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There is no reason why the driver would need to block other threads from
running the CPU while it is waiting for the SCU IPC to complete its
work. For this reason switch the driver to use usleep_range() instead
with a bit more relaxed polling loop.

Also add constant for the timeout and use the same value for both
polling and interrupt modes.

Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
This commit is contained in:
Mika Westerberg 2020-01-22 19:28:08 +03:00 committed by Andy Shevchenko
parent 74e9748b9b
commit e7b7ab3847
1 changed files with 14 additions and 15 deletions
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29
drivers/platform/x86/intel_scu_ipc.c
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@ -79,6 +79,9 @@ static struct intel_scu_ipc_dev ipcdev; /* Only one for now */
#define IPC_WRITE_BUFFER 0x80
#define IPC_READ_BUFFER 0x90
/* Timeout in jiffies */
#define IPC_TIMEOUT (3 * HZ)
static DEFINE_MUTEX(ipclock); /* lock used to prevent multiple call to SCU */
/*
@ -132,24 +135,20 @@ static inline u32 ipc_data_readl(struct intel_scu_ipc_dev *scu, u32 offset)
/* Wait till scu status is busy */
static inline int busy_loop(struct intel_scu_ipc_dev *scu)
{
u32 status = ipc_read_status(scu);
u32 loop_count = 100000;
unsigned long end = jiffies + msecs_to_jiffies(IPC_TIMEOUT);
do {
u32 status;
/* break if scu doesn't reset busy bit after huge retry */
while ((status & IPC_STATUS_BUSY) && --loop_count) {
udelay(1); /* scu processing time is in few u secods */
status = ipc_read_status(scu);
}
if (!(status & IPC_STATUS_BUSY))
return (status & IPC_STATUS_ERR) ? -EIO : 0;
if (status & IPC_STATUS_BUSY) {
dev_err(scu->dev, "IPC timed out");
return -ETIMEDOUT;
}
usleep_range(50, 100);
} while (time_before(jiffies, end));
if (status & IPC_STATUS_ERR)
return -EIO;
return 0;
dev_err(scu->dev, "IPC timed out");
return -ETIMEDOUT;
}
/* Wait till ipc ioc interrupt is received or timeout in 3 HZ */
@ -157,7 +156,7 @@ static inline int ipc_wait_for_interrupt(struct intel_scu_ipc_dev *scu)
{
int status;
if (!wait_for_completion_timeout(&scu->cmd_complete, 3 * HZ)) {
if (!wait_for_completion_timeout(&scu->cmd_complete, IPC_TIMEOUT)) {
dev_err(scu->dev, "IPC timed out\n");
return -ETIMEDOUT;
}