Re: [U-Boot] [Drivers PATCH 14/19] net/macb: workaround for transmission hang issue

[Bo Shen]

Hi All,

On 02/28/2013 08:59 PM, Albert ARIBAUD wrote:

On Sun, 3 Feb 2013 12:19:26 +0100, Albert ARIBAUD
<albert.u.b...@aribaud.net>  wrote:

Hi Vipin,

On Fri, 2 Nov 2012 23:09:59 +0530, Vipin Kumar<vipin.ku...@st.com>
wrote:

From: Shiraz Hashim<shiraz.has...@st.com>

It is observed on SPEAr320S RMII#1 interface that on transmitting
packets the MAC dma hangs randomly and constantly showing busy tx-go
state.

It comes out if this situation only when Transmission is disabled and
enabled again.

Since it happens randomly and u-boot doesn't require high performance we
disable TE and re-enable it on each transmission. We also change number
of transmit descriptor to 1 as we would not require more than it, further
it would not alter GMAC notion of transmit descriptor start queue as it
always point to same descriptor.

Signed-off-by: Shiraz Hashim<shiraz.has...@st.com>
---
  drivers/net/macb.c | 38 ++++++++++++++++++++++++++++++++++----
  1 file changed, 34 insertions(+), 4 deletions(-)

Tested on Atmel EK board. It works.

Tested-by: Bo Shen <voice.s...@atmel.com>

BTW, would this be implemented as a workaround only for SPEAr320S?

Best Regards,
Bo Shen

diff --git a/drivers/net/macb.c b/drivers/net/macb.c
index ac25b52..17bad33 100644
--- a/drivers/net/macb.c
+++ b/drivers/net/macb.c
@@ -55,7 +55,7 @@

  #define CONFIG_SYS_MACB_RX_BUFFER_SIZE                4096
  #define CONFIG_SYS_MACB_RX_RING_SIZE          (CONFIG_SYS_MACB_RX_BUFFER_SIZE 
/ 128)
-#define CONFIG_SYS_MACB_TX_RING_SIZE           16
+#define CONFIG_SYS_MACB_TX_RING_SIZE           1
  #define CONFIG_SYS_MACB_TX_TIMEOUT            1000
  #define CONFIG_SYS_MACB_AUTONEG_TIMEOUT       5000000

@@ -226,7 +226,13 @@ static int macb_send(struct eth_device *netdev, void 
*packet, int length)
        macb->tx_ring[tx_head].ctrl = ctrl;
        macb->tx_ring[tx_head].addr = paddr;
        barrier();
-       macb_writel(macb, NCR, MACB_BIT(TE) | MACB_BIT(RE) | MACB_BIT(TSTART));
+       /*
+        * Due to issues on SPEAr320 RMII, disable TE first so that
+        * controller can come out if it is hanged during transmission
+        */
+       macb_writel(macb, NCR, macb_readl(macb, NCR)&  ~MACB_BIT(TE));
+       macb_writel(macb, NCR, macb_readl(macb, NCR) |
+                       MACB_BIT(TE) | MACB_BIT(TSTART));

        /*
         * I guess this is necessary because the networking core may
@@ -444,6 +450,31 @@ static int macb_phy_init(struct macb_device *macb)
        }
  }

+static void macb_reset_hw(struct macb_device *bp)
+{
+       /* Make sure we have the write buffer for ourselves */
+       barrier();
+       /*
+        * Disable RX and TX (XXX: Should we halt the transmission
+        * more gracefully?) and we should not close the mdio port
+        */
+       macb_writel(bp, NCR, 0);
+
+       /* Clear the stats registers (XXX: Update stats first?) */
+       macb_writel(bp, NCR, MACB_BIT(CLRSTAT));
+
+       /* keep the mdio port , otherwise other eth will not work */
+       macb_writel(bp, NCR, MACB_BIT(MPE));
+
+       /* Clear all status flags */
+       macb_writel(bp, TSR, ~0UL);
+       macb_writel(bp, RSR, ~0UL);
+
+       /* Disable all interrupts */
+       macb_writel(bp, IDR, ~0UL);
+       macb_readl(bp, ISR);
+}
+
  static int macb_init(struct eth_device *netdev, bd_t *bd)
  {
        struct macb_device *macb = to_macb(netdev);
@@ -520,8 +551,7 @@ static void macb_halt(struct eth_device *netdev)
                tsr = macb_readl(macb, TSR);
        } while (tsr&  MACB_BIT(TGO));

-       /* Disable TX and RX, and clear statistics */
-       macb_writel(macb, NCR, MACB_BIT(CLRSTAT));
+       macb_reset_hw(macb);
  }

  static int macb_write_hwaddr(struct eth_device *dev)

This patch did not reappear in later versions of the series, and no
other standalone patch seems to match it. Was it dropped?

Ping?

Amicalement,

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