* (C) Copyright 2007 Pengutronix, Sascha Hauer <s.hauer@pengutronix.de>
* (C) Copyright 2007 Pengutronix, Juergen Beisert <j.beisert@pengutronix.de>
*
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License as
- * published by the Free Software Foundation; either version 2 of
- * the License, or (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
- * MA 02111-1307 USA
+ * SPDX-License-Identifier: GPL-2.0+
*/
#include <common.h>
}
memset(fec->tbd_base, 0, size);
fec_tbd_init(fec);
- flush_dcache_range((unsigned)fec->tbd_base, size);
}
/*
addr = (uint32_t)fec->tbd_base;
flush_dcache_range(addr, addr + size);
+ /*
+ * Below we read the DMA descriptor's last four bytes back from the
+ * DRAM. This is important in order to make sure that all WRITE
+ * operations on the bus that were triggered by previous cache FLUSH
+ * have completed.
+ *
+ * Otherwise, on MX28, it is possible to observe a corruption of the
+ * DMA descriptors. Please refer to schematic "Figure 1-2" in MX28RM
+ * for the bus structure of MX28. The scenario is as follows:
+ *
+ * 1) ARM core triggers a series of WRITEs on the AHB_ARB2 bus going
+ * to DRAM due to flush_dcache_range()
+ * 2) ARM core writes the FEC registers via AHB_ARB2
+ * 3) FEC DMA starts reading/writing from/to DRAM via AHB_ARB3
+ *
+ * Note that 2) does sometimes finish before 1) due to reordering of
+ * WRITE accesses on the AHB bus, therefore triggering 3) before the
+ * DMA descriptor is fully written into DRAM. This results in occasional
+ * corruption of the DMA descriptor.
+ */
+ readl(addr + size - 4);
+
/*
* Enable SmartDMA transmit task
*/
if (fec_get_hwaddr(edev, dev_id, ethaddr) == 0) {
debug("got MAC%d address from fuse: %pM\n", dev_id, ethaddr);
memcpy(edev->enetaddr, ethaddr, 6);
+ if (!getenv("ethaddr"))
+ eth_setenv_enetaddr("ethaddr", ethaddr);
}
return ret;
err3: