[PATCH 4/9] net: dwc_eth_qos: Set DMA_MODE SWR bit to reset the MAC

[Marek Vasut]

The driver currently only waits for DMA_MODE SWR bit to clear itself.
This is insufficient e.g. on i.MX8M Plus, where the MAC must be reset
before IOMUX GPR[1] content is latched into the MAC and used. Without
the proper reset, the i.MX8M Plus MAC variant does not take the value
in IOMUX GPR[1] into account, which makes it impossible e.g. to switch
interface mode from RGMII to any other.

Since proper reset is desired in general to put the block into defined
state, always assert the DMA_MODE SWR bit before waiting for the bit
to clear itself.

Signed-off-by: Marek Vasut <marex at denx.de>
---
Cc: "Ariel D'Alessandro" <ariel.dalessandro at collabora.com>
Cc: "NXP i.MX U-Boot Team" <uboot-imx at nxp.com>
Cc: Andrey Zhizhikin <andrey.zhizhikin at leica-geosystems.com>
Cc: Fabio Estevam <festevam at gmail.com>
Cc: Joe Hershberger <joe.hershberger at ni.com>
Cc: Lukasz Majewski <lukma at denx.de>
Cc: Marcel Ziswiler <marcel.ziswiler at toradex.com>
Cc: Marek Vasut <marex at denx.de>
Cc: Michael Trimarchi <michael at amarulasolutions.com>
Cc: Peng Fan <peng.fan at nxp.com>
Cc: Ramon Fried <rfried.dev at gmail.com>
Cc: Sean Anderson <seanga2 at gmail.com>
Cc: Stefano Babic <sbabic at denx.de>
Cc: Tim Harvey <tharvey at gateworks.com>
Cc: Tommaso Merciai <tommaso.merciai at amarulasolutions.com>
Cc: u-boot at lists.denx.de
---
 drivers/net/dwc_eth_qos.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/net/dwc_eth_qos.c b/drivers/net/dwc_eth_qos.c
index cd2def4ba21..d488bd0c288 100644
--- a/drivers/net/dwc_eth_qos.c
+++ b/drivers/net/dwc_eth_qos.c
@@ -761,6 +761,12 @@ static int eqos_start(struct udevice *dev)
 
 	eqos->reg_access_ok = true;
 
+	/*
+	 * Assert the SWR first, the actually reset the MAC and to latch in
+	 * e.g. i.MX8M Plus GPR[1] content, which selects interface mode.
+	 */
+	setbits_le32(&eqos->dma_regs->mode, EQOS_DMA_MODE_SWR);
+
 	ret = wait_for_bit_le32(&eqos->dma_regs->mode,
 				EQOS_DMA_MODE_SWR, false,
 				eqos->config->swr_wait, false);
-- 
2.39.0