[PATCH net-next v1 2/2] lan743x: replace polling loop by wait_event_timeout()

[Sven Van Asbroeck]

From: Sven Van Asbroeck <thesve...@gmail.com>

The driver's ISR sends a 'software interrupt' event to the probe()
thread using the following method:
- probe(): write 0 to flag, enable s/w interrupt
- probe(): poll on flag, relax using usleep_range()
- ISR    : write 1 to flag

Replace with wake_up() / wait_event_timeout(). Besides being easier
to get right, this abstraction has better timing and memory
consistency properties.

Tested-by: Sven Van Asbroeck <thesve...@gmail.com> # lan7430
Signed-off-by: Sven Van Asbroeck <thesve...@gmail.com>
---

To: Bryan Whitehead <bryan.whiteh...@microchip.com>
To: Jakub Kicinski <k...@kernel.org>
To: "David S. Miller" <da...@davemloft.net>
Cc: Andrew Lunn <and...@lunn.ch>
Cc: Microchip Linux Driver Support <unglinuxdri...@microchip.com>
Cc: net...@vger.kernel.org
Cc: linux-kernel@vger.kernel.org

 drivers/net/ethernet/microchip/lan743x_main.c | 28 +++++++++----------
 drivers/net/ethernet/microchip/lan743x_main.h |  3 +-
 2 files changed, 15 insertions(+), 16 deletions(-)

diff --git a/drivers/net/ethernet/microchip/lan743x_main.c 
b/drivers/net/ethernet/microchip/lan743x_main.c
index bdc80098c240..96d34b001198 100644
--- a/drivers/net/ethernet/microchip/lan743x_main.c
+++ b/drivers/net/ethernet/microchip/lan743x_main.c
@@ -146,7 +146,8 @@ static void lan743x_intr_software_isr(struct 
lan743x_adapter *adapter)
 
        /* disable the interrupt to prevent repeated re-triggering */
        lan743x_csr_write(adapter, INT_EN_CLR, INT_BIT_SW_GP_);
-       intr->software_isr_flag = 1;
+       intr->software_isr_flag = true;
+       wake_up(&intr->software_isr_wq);
 }
 
 static void lan743x_tx_isr(void *context, u32 int_sts, u32 flags)
@@ -344,27 +345,22 @@ static irqreturn_t lan743x_intr_entry_isr(int irq, void 
*ptr)
 static int lan743x_intr_test_isr(struct lan743x_adapter *adapter)
 {
        struct lan743x_intr *intr = &adapter->intr;
-       int result = -ENODEV;
-       int timeout = 10;
+       int ret;
 
-       intr->software_isr_flag = 0;
+       intr->software_isr_flag = false;
 
-       /* enable interrupt */
+       /* enable and activate test interrupt */
        lan743x_csr_write(adapter, INT_EN_SET, INT_BIT_SW_GP_);
-
-       /* activate interrupt here */
        lan743x_csr_write(adapter, INT_SET, INT_BIT_SW_GP_);
-       while ((timeout > 0) && (!(intr->software_isr_flag))) {
-               usleep_range(1000, 20000);
-               timeout--;
-       }
 
-       if (intr->software_isr_flag)
-               result = 0;
+       ret = wait_event_timeout(intr->software_isr_wq,
+                                intr->software_isr_flag,
+                                msecs_to_jiffies(200));
 
-       /* disable interrupts */
+       /* disable test interrupt */
        lan743x_csr_write(adapter, INT_EN_CLR, INT_BIT_SW_GP_);
-       return result;
+
+       return ret > 0 ? 0 : -ENODEV;
 }
 
 static int lan743x_intr_register_isr(struct lan743x_adapter *adapter,
@@ -538,6 +534,8 @@ static int lan743x_intr_open(struct lan743x_adapter 
*adapter)
                flags |= LAN743X_VECTOR_FLAG_SOURCE_ENABLE_R2C;
        }
 
+       init_waitqueue_head(&intr->software_isr_wq);
+
        ret = lan743x_intr_register_isr(adapter, 0, flags,
                                        INT_BIT_ALL_RX_ | INT_BIT_ALL_TX_ |
                                        INT_BIT_ALL_OTHER_,
diff --git a/drivers/net/ethernet/microchip/lan743x_main.h 
b/drivers/net/ethernet/microchip/lan743x_main.h
index a536f4a4994d..b92864913e6c 100644
--- a/drivers/net/ethernet/microchip/lan743x_main.h
+++ b/drivers/net/ethernet/microchip/lan743x_main.h
@@ -616,7 +616,8 @@ struct lan743x_intr {
        int                     number_of_vectors;
        bool                    using_vectors;
 
-       int                     software_isr_flag;
+       bool                    software_isr_flag;
+       wait_queue_head_t       software_isr_wq;
 };
 
 #define LAN743X_MAX_FRAME_SIZE                 (9 * 1024)
-- 
2.17.1