From c61221948c30710f2316b264f61efbf61c92a4aa Mon Sep 17 00:00:00 2001 From: Quentin Schulz Date: Mon, 4 Jun 2018 12:17:33 +0200 Subject: [PATCH] net: designware: set the PS bit when resetting DMA bus in MII configuration On the SPEAr600 SoC, which has the dwmac1000 variant of the IP block, the DMA reset never succeeds when a MII PHY is used (no problem with a GMII PHY). The designware_eth_init() function sets the DMAMAC_SRST bit in the DMA_BUS_MODE register, and then polls until this bit clears. When a MII PHY is used, with the current driver, this bit never clears and the driver therefore doesn't work. The reason is that the PS bit of the GMAC_CONTROL register should be correctly configured for the DMA reset to work. When the PS bit is 0, it tells the MAC we have a GMII PHY, when the PS bit is 1, it tells the MAC we have a MII PHY. Doing a DMA reset clears all registers, so the PS bit is cleared as well. This makes the DMA reset work fine with a GMII PHY. However, with MII PHY, the PS bit should be set. We have identified this issue thanks to two SPEAr600 platform: - One equipped with a GMII PHY, with which the existing driver was working fine. - One equipped with a MII PHY, where the current driver fails because the DMA reset times out. Note: Taken from https://www.spinics.net/lists/netdev/msg432578.html Signed-off-by: Quentin Schulz Acked-by: Joe Hershberger --- drivers/net/designware.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/drivers/net/designware.c b/drivers/net/designware.c index cf12521..10a8709 100644 --- a/drivers/net/designware.c +++ b/drivers/net/designware.c @@ -280,6 +280,15 @@ int designware_eth_init(struct dw_eth_dev *priv, u8 *enetaddr) writel(readl(&dma_p->busmode) | DMAMAC_SRST, &dma_p->busmode); + /* + * When a MII PHY is used, we must set the PS bit for the DMA + * reset to succeed. + */ + if (priv->phydev->interface == PHY_INTERFACE_MODE_MII) + writel(readl(&mac_p->conf) | MII_PORTSELECT, &mac_p->conf); + else + writel(readl(&mac_p->conf) & ~MII_PORTSELECT, &mac_p->conf); + start = get_timer(0); while (readl(&dma_p->busmode) & DMAMAC_SRST) { if (get_timer(start) >= CONFIG_MACRESET_TIMEOUT) { -- 2.7.4