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

[Albert ARIBAUD]

Hi Vipin,

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

> From: Shiraz Hashim <shiraz.hashim at 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.hashim at st.com>
> ---
>  drivers/net/macb.c | 38 ++++++++++++++++++++++++++++++++++----
>  1 file changed, 34 insertions(+), 4 deletions(-)
> 
> 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?

Amicalement,
-- 
Albert.