Hi,
Sorry, but I don't think this patch has been sufficiently tested against a
mainline kernel. The driver wont even probe the way it is right now.
On 07/21/2015 01:14 AM, Xander Huff wrote:
The driver currently registers a pair of irq handlers using
request_threaded_irq(), however the synchronization mechanism between the
hardirq and the threadedirq handler is a regular spinlock.
If everything runs in threaded context we don't really need the spinlock
anymore and can use the mutex throughout.
Unfortunately, this breaks PREEMPT_RT builds, where a spinlock can sleep,
and is thus not able to be acquired from a hardirq handler. This patch gets
rid of the hardirq handler and pushes all interrupt handling into the
threaded context.
We actually might as well run everything in the hardirq handler (which will
be threaded in PREEMPT_RT). The reason why we have the threaded handler is
because xadc_handle_event() used to sleep, but it doesn't do this anymore.
Signed-off-by: Xander Huff <xander.huff@xxxxxx>
---
drivers/iio/adc/xilinx-xadc-core.c | 37 ++++++++-----------------------------
1 file changed, 8 insertions(+), 29 deletions(-)
diff --git a/drivers/iio/adc/xilinx-xadc-core.c b/drivers/iio/adc/xilinx-xadc-core.c
index ce93bd8..e16afdb 100644
--- a/drivers/iio/adc/xilinx-xadc-core.c
+++ b/drivers/iio/adc/xilinx-xadc-core.c
@@ -267,40 +267,15 @@ static void xadc_zynq_unmask_worker(struct work_struct *work)
xadc_zynq_update_intmsk(xadc, 0, 0);
spin_unlock_irq(&xadc->lock);
-
- /* if still pending some alarm re-trigger the timer */
- if (xadc->zynq_masked_alarm) {
- schedule_delayed_work(&xadc->zynq_unmask_work,
- msecs_to_jiffies(XADC_ZYNQ_UNMASK_TIMEOUT));
- }
}
static irqreturn_t xadc_zynq_threaded_interrupt_handler(int irq, void *devid)
{
struct iio_dev *indio_dev = devid;
struct xadc *xadc = iio_priv(indio_dev);
- unsigned int alarm;
-
- spin_lock_irq(&xadc->lock);
- alarm = xadc->zynq_alarm;
- xadc->zynq_alarm = 0;
- spin_unlock_irq(&xadc->lock);
-
- xadc_handle_events(indio_dev, xadc_zynq_transform_alarm(alarm));
-
- /* unmask the required interrupts in timer. */
- schedule_delayed_work(&xadc->zynq_unmask_work,
- msecs_to_jiffies(XADC_ZYNQ_UNMASK_TIMEOUT));
-
With nobody scheduling the unmask worker interrupts will stay disabled
indefinitely after they fired once, that's not very useful.
- return IRQ_HANDLED;
-}
-
-static irqreturn_t xadc_zynq_interrupt_handler(int irq, void *devid)
-{
- struct iio_dev *indio_dev = devid;
- struct xadc *xadc = iio_priv(indio_dev);
irqreturn_t ret = IRQ_HANDLED;
uint32_t status;
+ unsigned int alarm;
xadc_read_reg(xadc, XADC_ZYNQ_REG_INTSTS, &status);
@@ -312,7 +287,6 @@ static irqreturn_t xadc_zynq_interrupt_handler(int irq, void *devid)
spin_lock(&xadc->lock);
xadc_write_reg(xadc, XADC_ZYNQ_REG_INTSTS, status);
-
if (status & XADC_ZYNQ_INT_DFIFO_GTH) {
xadc_zynq_update_intmsk(xadc, XADC_ZYNQ_INT_DFIFO_GTH,
XADC_ZYNQ_INT_DFIFO_GTH);
@@ -330,8 +304,14 @@ static irqreturn_t xadc_zynq_interrupt_handler(int irq, void *devid)
xadc_zynq_update_intmsk(xadc, 0, 0);
ret = IRQ_WAKE_THREAD;
}
+
+ alarm = xadc->zynq_alarm;
+ xadc->zynq_alarm = 0;
With all running in the same handler we don't need those anymore.
+
spin_unlock(&xadc->lock);
+ xadc_handle_events(indio_dev, xadc_zynq_transform_alarm(alarm));
+
return ret;
}
@@ -436,7 +416,6 @@ static const struct xadc_ops xadc_zynq_ops = {
.write = xadc_zynq_write_adc_reg,
.setup = xadc_zynq_setup,
.get_dclk_rate = xadc_zynq_get_dclk_rate,
- .interrupt_handler = xadc_zynq_interrupt_handler,
The corresponding field should be removed from the xadc_ops struct and then
you'll also notice that interrupts now don't work anymore for the AXI
interface version.
.threaded_interrupt_handler = xadc_zynq_threaded_interrupt_handler,
.update_alarm = xadc_zynq_update_alarm,
};
@@ -1225,7 +1204,7 @@ static int xadc_probe(struct platform_device *pdev)
if (ret)
goto err_free_samplerate_trigger;
- ret = request_threaded_irq(irq, xadc->ops->interrupt_handler,
+ ret = request_threaded_irq(irq, NULL,
xadc->ops->threaded_interrupt_handler,
0, dev_name(&pdev->dev), indio_dev);
if (ret)
--
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