Commit 749a2b6 (net/macb: clear tx/rx completion flags in ISR)
introduces clear-on-write on ISR register. This behavior is not always
implemented when using Cadence MACB/GEM and is breaking other platforms.
We are using a new Device Tree compatibility string and a capability
property to actually activate this clear-on-write behavior on ISR.

Reported-by: Hein Tibosch <[email protected]>
Signed-off-by: Nicolas Ferre <[email protected]>
---
 Documentation/devicetree/bindings/net/macb.txt |  2 ++
 drivers/net/ethernet/cadence/macb.c            | 15 +++++++++++++--
 drivers/net/ethernet/cadence/macb.h            |  5 +++++
 3 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/Documentation/devicetree/bindings/net/macb.txt 
b/Documentation/devicetree/bindings/net/macb.txt
index 44afa0e..13ec4f6 100644
--- a/Documentation/devicetree/bindings/net/macb.txt
+++ b/Documentation/devicetree/bindings/net/macb.txt
@@ -6,6 +6,8 @@ Required properties:
   Use "cdns,at32ap7000-macb" for other 10/100 usage or use the generic form: 
"cdns,macb".
   Use "cnds,pc302-gem" for Picochip picoXcell pc302 and later devices based on
   the Cadence GEM, or the generic form: "cdns,gem".
+  Use "cdns,zynq-7000-gem" for devices based on Cadence GEM with alternative
+  options enabled (ISR clear on write).
 - reg: Address and length of the register set for the device
 - interrupts: Should contain macb interrupt
 - phy-mode: String, operation mode of the PHY interface.
diff --git a/drivers/net/ethernet/cadence/macb.c 
b/drivers/net/ethernet/cadence/macb.c
index 6be513d..628f2b0 100644
--- a/drivers/net/ethernet/cadence/macb.c
+++ b/drivers/net/ethernet/cadence/macb.c
@@ -485,7 +485,8 @@ static void macb_tx_interrupt(struct macb *bp)
        status = macb_readl(bp, TSR);
        macb_writel(bp, TSR, status);
 
-       macb_writel(bp, ISR, MACB_BIT(TCOMP));
+       if (bp->caps & MACB_CAPS_ISR_CLEAR_ON_WRITE)
+               macb_writel(bp, ISR, MACB_BIT(TCOMP));
 
        netdev_vdbg(bp->dev, "macb_tx_interrupt status = 0x%03lx\n",
                (unsigned long)status);
@@ -738,7 +739,8 @@ static irqreturn_t macb_interrupt(int irq, void *dev_id)
                         * now.
                         */
                        macb_writel(bp, IDR, MACB_RX_INT_FLAGS);
-                       macb_writel(bp, ISR, MACB_BIT(RCOMP));
+                       if (bp->caps & MACB_CAPS_ISR_CLEAR_ON_WRITE)
+                               macb_writel(bp, ISR, MACB_BIT(RCOMP));
 
                        if (napi_schedule_prep(&bp->napi)) {
                                netdev_vdbg(bp->dev, "scheduling RX softirq\n");
@@ -1474,6 +1476,10 @@ static const struct of_device_id macb_dt_ids[] = {
        { .compatible = "cdns,macb" },
        { .compatible = "cdns,pc302-gem" },
        { .compatible = "cdns,gem" },
+       {
+               .compatible = "cdns,zynq-7000-gem",
+               .data = (void *)MACB_CAPS_ISR_CLEAR_ON_WRITE,
+       },
        { /* sentinel */ }
 };
 MODULE_DEVICE_TABLE(of, macb_dt_ids);
@@ -1484,6 +1490,7 @@ static int __init macb_probe(struct platform_device *pdev)
        struct macb_platform_data *pdata;
        struct resource *regs;
        struct net_device *dev;
+       const struct of_device_id *dev_id;
        struct macb *bp;
        struct phy_device *phydev;
        u32 config;
@@ -1558,6 +1565,10 @@ static int __init macb_probe(struct platform_device 
*pdev)
 
        dev->base_addr = regs->start;
 
+       dev_id = of_match_device(macb_dt_ids, &pdev->dev);
+       if (dev_id)
+               bp->caps = (u32)dev_id->data;
+
        /* Set MII management clock divider */
        config = macb_mdc_clk_div(bp);
        config |= macb_dbw(bp);
diff --git a/drivers/net/ethernet/cadence/macb.h 
b/drivers/net/ethernet/cadence/macb.h
index 993d703..5d622fe 100644
--- a/drivers/net/ethernet/cadence/macb.h
+++ b/drivers/net/ethernet/cadence/macb.h
@@ -323,6 +323,9 @@
 #define MACB_MAN_READ                          2
 #define MACB_MAN_CODE                          2
 
+/* Capability mask bits */
+#define MACB_CAPS_ISR_CLEAR_ON_WRITE           0x1
+
 /* Bit manipulation macros */
 #define MACB_BIT(name)                                 \
        (1 << MACB_##name##_OFFSET)
@@ -574,6 +577,8 @@ struct macb {
        unsigned int            speed;
        unsigned int            duplex;
 
+       u32                     caps;
+
        phy_interface_t         phy_interface;
 
        /* AT91RM9200 transmit */
-- 
1.8.0

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