DM9000: Make driver work properly for DM9000A

The DM9000A network controller does not work with the U-boot DM9000x driver.
Analysis showed that many incoming packets are lost.

The DM9000A Application Notes V1.20 (section 5.6.1) recommend that the poll to
check for a valid rx packet be done on the interrupt status register, not
directly by performing the dummy read and the rx status check as is currently
the case in the u-boot driver.

When the recommended poll is done as suggested the driver starts working
correctly on 10Mbit/HD, but on 100MBit/FD packets come in faster so that there
can be more than 1 package in the fifo at the same time.

The driver must perform the rx-status check in a loop and read and handle all
packages until there is no more left _after_ the interrupt RX flag is set.

This change has been tested with DM9000A, DM9000E, DM9000EP.

Signed-off-by: Remy Bohmer <linux@bohmer.net>
Signed-off-by: Ben Warren <biggerbadderben@gmail.com>

diff --git a/drivers/net/dm9000x.c b/drivers/net/dm9000x.c
index 5b00e95..08248f4 100644 (file)
--- a/drivers/net/dm9000x.c
+++ b/drivers/net/dm9000x.c
@@ -40,6 +40,10 @@ v1.2   03/18/2003       Weilun Huang <weilun_huang@davicom.com.tw>:
                                Sascha Hauer <saschahauer@web.de>
 
        06/03/2008      Remy Bohmer <linux@bohmer.net>
+                       - Fixed the driver to work with DM9000A.
+                         (check on ISR receive status bit before reading the
+                         FIFO as described in DM9000 programming guide and
+                         application notes)
                        - Added autodetect of databus width.
                        - Made debug code compile again.
                        - Adapt eth_send such that it matches the DM9000*
@@ -598,53 +602,64 @@ eth_rx(void)
        u16 RxStatus, RxLen = 0;
        struct board_info *db = &dm9000_info;
 
-       /* Check packet ready or not */
-       DM9000_ior(DM9000_MRCMDX);      /* Dummy read */
-       rxbyte = DM9000_inb(DM9000_DATA);       /* Got most updated data */
-       if (rxbyte == 0)
+       /* Check packet ready or not, we must check
+          the ISR status first for DM9000A */
+       if (!(DM9000_ior(DM9000_ISR) & 0x01)) /* Rx-ISR bit must be set. */
                return 0;
 
-       /* Status check: this byte must be 0 or 1 */
-       if (rxbyte > 1) {
-               DM9000_iow(DM9000_RCR, 0x00);   /* Stop Device */
-               DM9000_iow(DM9000_ISR, 0x80);   /* Stop INT request */
-               DM9000_DBG("rx status check: %d\n", rxbyte);
-       }
-       DM9000_DBG("receiving packet\n");
+       DM9000_iow(DM9000_ISR, 0x01); /* clear PR status latched in bit 0 */
 
-       /* A packet ready now  & Get status/length */
-       DM9000_outb(DM9000_MRCMD, DM9000_IO);
+       /* There is _at least_ 1 package in the fifo, read them all */
+       for (;;) {
+               DM9000_ior(DM9000_MRCMDX);      /* Dummy read */
 
-       (db->rx_status)(&RxStatus, &RxLen);
+               /* Get most updated data */
+               rxbyte = DM9000_inb(DM9000_DATA);
 
-       DM9000_DBG("rx status: 0x%04x rx len: %d\n", RxStatus, RxLen);
+               /* Status check: this byte must be 0 or 1 */
+               if (rxbyte > DM9000_PKT_RDY) {
+                       DM9000_iow(DM9000_RCR, 0x00);   /* Stop Device */
+                       DM9000_iow(DM9000_ISR, 0x80);   /* Stop INT request */
+                       printf("DM9000 error: status check fail: 0x%x\n",
+                               rxbyte);
+                       return 0;
+               }
 
-       /* Move data from DM9000 */
-       /* Read received packet from RX SRAM */
-       (db->inblk)(rdptr, RxLen);
+               if (rxbyte != DM9000_PKT_RDY)
+                       return 0; /* No packet received, ignore */
+
+               DM9000_DBG("receiving packet\n");
+
+               /* A packet ready now  & Get status/length */
+               (db->rx_status)(&RxStatus, &RxLen);
+
+               DM9000_DBG("rx status: 0x%04x rx len: %d\n", RxStatus, RxLen);
+
+               /* Move data from DM9000 */
+               /* Read received packet from RX SRAM */
+               (db->inblk)(rdptr, RxLen);
+
+               if ((RxStatus & 0xbf00) || (RxLen < 0x40)
+                       || (RxLen > DM9000_PKT_MAX)) {
+                       if (RxStatus & 0x100) {
+                               printf("rx fifo error\n");
+                       }
+                       if (RxStatus & 0x200) {
+                               printf("rx crc error\n");
+                       }
+                       if (RxStatus & 0x8000) {
+                               printf("rx length error\n");
+                       }
+                       if (RxLen > DM9000_PKT_MAX) {
+                               printf("rx length too big\n");
+                               dm9000_reset();
+                       }
+               } else {
+                       DM9000_DMP_PACKET("eth_rx", rdptr, RxLen);
 
-       if ((RxStatus & 0xbf00) || (RxLen < 0x40)
-           || (RxLen > DM9000_PKT_MAX)) {
-               if (RxStatus & 0x100) {
-                       printf("rx fifo error\n");
+                       DM9000_DBG("passing packet to upper layer\n");
+                       NetReceive(NetRxPackets[0], RxLen);
                }
-               if (RxStatus & 0x200) {
-                       printf("rx crc error\n");
-               }
-               if (RxStatus & 0x8000) {
-                       printf("rx length error\n");
-               }
-               if (RxLen > DM9000_PKT_MAX) {
-                       printf("rx length too big\n");
-                       dm9000_reset();
-               }
-       } else {
-               DM9000_DMP_PACKET("eth_rx", rdptr, RxLen);
-
-               /* Pass to upper layer */
-               DM9000_DBG("passing packet to upper layer\n");
-               NetReceive(NetRxPackets[0], RxLen);
-               return RxLen;
        }
        return 0;
 }