[RFC 09/19] HSI: omap_ssi_port: prepare start_tx/stop_tx for blocking pm_runtime calls

From: Sebastian Reichel
Date: Sat Jun 18 2016 - 12:31:13 EST


ssi_start_tx and ssi_stop_tx may be called from atomic context. Once
pm_runtime_irq_safe() is removed for omap-ssi, this will fail, due
to blocking pm_runtime_*_sync() calls.

This fixes ssi_stop_tx by using non-sync API and ssi_start_tx by
using a worker thread.

Signed-off-by: Sebastian Reichel <sre@xxxxxxxxxx>
---
drivers/hsi/controllers/omap_ssi.h | 2 ++
drivers/hsi/controllers/omap_ssi_port.c | 23 ++++++++++++++++++-----
2 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/drivers/hsi/controllers/omap_ssi.h b/drivers/hsi/controllers/omap_ssi.h
index 6cdaad8805f7..5467f61e5086 100644
--- a/drivers/hsi/controllers/omap_ssi.h
+++ b/drivers/hsi/controllers/omap_ssi.h
@@ -79,6 +79,7 @@ struct omap_ssm_ctx {
* @pio_tasklet: Bottom half for PIO transfers and events
* @flags: flags to keep track of states
* @wk_refcount: Reference count for output wake line
+ * @work: worker for starting TX
* @sys_mpu_enable: Context for the interrupt enable register for irq 0
* @sst: Context for the synchronous serial transmitter
* @ssr: Context for the synchronous serial receiver
@@ -103,6 +104,7 @@ struct omap_ssi_port {
bool wktest:1; /* FIXME: HACK to be removed */
unsigned long flags;
unsigned int wk_refcount;
+ struct work_struct work;
/* OMAP SSI port context */
u32 sys_mpu_enable; /* We use only one irq */
struct omap_ssm_ctx sst;
diff --git a/drivers/hsi/controllers/omap_ssi_port.c b/drivers/hsi/controllers/omap_ssi_port.c
index 0d3452393670..cc56d0ee82a2 100644
--- a/drivers/hsi/controllers/omap_ssi_port.c
+++ b/drivers/hsi/controllers/omap_ssi_port.c
@@ -567,12 +567,22 @@ static int ssi_flush(struct hsi_client *cl)
return 0;
}

+static void start_tx_work(struct work_struct *work)
+{
+ struct omap_ssi_port *omap_port =
+ container_of(work, struct omap_ssi_port, work);
+ struct hsi_port *port = to_hsi_port(omap_port->dev);
+ struct hsi_controller *ssi = to_hsi_controller(port->device.parent);
+ struct omap_ssi_controller *omap_ssi = hsi_controller_drvdata(ssi);
+
+ pm_runtime_get_sync(omap_port->pdev); /* Grab clocks */
+ writel(SSI_WAKE(0), omap_ssi->sys + SSI_SET_WAKE_REG(port->num));
+}
+
static int ssi_start_tx(struct hsi_client *cl)
{
struct hsi_port *port = hsi_get_port(cl);
struct omap_ssi_port *omap_port = hsi_port_drvdata(port);
- struct hsi_controller *ssi = to_hsi_controller(port->device.parent);
- struct omap_ssi_controller *omap_ssi = hsi_controller_drvdata(ssi);

dev_dbg(&port->device, "Wake out high %d\n", omap_port->wk_refcount);

@@ -581,10 +591,10 @@ static int ssi_start_tx(struct hsi_client *cl)
spin_unlock_bh(&omap_port->wk_lock);
return 0;
}
- pm_runtime_get_sync(omap_port->pdev); /* Grab clocks */
- writel(SSI_WAKE(0), omap_ssi->sys + SSI_SET_WAKE_REG(port->num));
spin_unlock_bh(&omap_port->wk_lock);

+ schedule_work(&omap_port->work);
+
return 0;
}

@@ -604,9 +614,10 @@ static int ssi_stop_tx(struct hsi_client *cl)
return 0;
}
writel(SSI_WAKE(0), omap_ssi->sys + SSI_CLEAR_WAKE_REG(port->num));
- pm_runtime_put_sync(omap_port->pdev); /* Release clocks */
spin_unlock_bh(&omap_port->wk_lock);

+ pm_runtime_put(omap_port->pdev); /* Release clocks */
+
return 0;
}

@@ -1149,6 +1160,8 @@ static int ssi_port_probe(struct platform_device *pd)
omap_port->pdev = &pd->dev;
omap_port->port_id = port_id;

+ INIT_WORK(&omap_port->work, start_tx_work);
+
/* initialize HSI port */
port->async = ssi_async;
port->setup = ssi_setup;
--
2.8.1