one source of excess latency in hm2_spi / hal_spidev is latency due
to async transfers. Make the __spi_sync primitive actually synchronous,
rather than building on an asynchronous primitive.
---
drivers/spi/spi.c | 22 ++++++++++++++++------
1 file changed, 16 insertions(+), 6 deletions(-)
diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 19ee901..55404b5 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -664,10 +664,18 @@ void spi_finalize_current_message(struct spi_master
*master)
struct spi_message *mesg;
unsigned long flags;
+ if(!master->cur_msg)
+ return;
+
spin_lock_irqsave(&master->queue_lock, flags);
mesg = master->cur_msg;
master->cur_msg = NULL;
+ if(!mesg) {
+ spin_unlock_irqrestore(&master->queue_lock, flags);
+ return;
+ }
+
queue_kthread_work(&master->kworker, &master->pump_messages);
spin_unlock_irqrestore(&master->queue_lock, flags);
@@ -1490,24 +1498,26 @@ static int __spi_sync(struct spi_device *spi, struct
spi_message *message,
int bus_locked)
{
DECLARE_COMPLETION_ONSTACK(done);
- int status;
+ int status = 0;
struct spi_master *master = spi->master;
message->complete = spi_complete;
message->context = &done;
+ message->spi = spi;
if (!bus_locked)
mutex_lock(&master->bus_lock_mutex);
- status = spi_async_locked(spi, message);
+ if(master->prepare_transfer_hardware)
+ status = master->prepare_transfer_hardware(master);
+ if(status >= 0)
+ status = master->transfer_one_message(master, message);
+ if(status >= 0 && master->unprepare_transfer_hardware)
+ status = master->unprepare_transfer_hardware(master);
if (!bus_locked)
mutex_unlock(&master->bus_lock_mutex);
- if (status == 0) {
- wait_for_completion(&done);
- status = message->status;
- }
message->context = NULL;
return status;
}
--
2.1.0
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