Messages in this thread | | | Date | Sun, 15 Jul 2007 12:27:26 -0600 | From | Robert Hancock <> | Subject | Re: [PATCH try#2] Blackfin ethernet driver: on chip ethernet MAC controller driver |
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Bryan Wu wrote: > On Sun, 2007-07-15 at 14:17 +0200, Michael Buesch wrote: >> On Sunday 15 July 2007 14:07:44 Bryan Wu wrote: >>> @@ -483,9 +487,12 @@ >>> >>> void setup_mac_addr(u8 * mac_addr) >>> { >>> + u32 addr_low = le32_to_cpu(*(u32 *) & mac_addr[0]); >>> + u16 addr_hi = le16_to_cpu(*(u16 *) & mac_addr[4]); >>> + >>> /* this depends on a little-endian machine */ >>> - bfin_write_EMAC_ADDRLO(*(u32 *) & mac_addr[0]); >>> - bfin_write_EMAC_ADDRHI(*(u16 *) & mac_addr[4]); >>> + bfin_write_EMAC_ADDRLO(addr_low); >>> + bfin_write_EMAC_ADDRHI(addr_hi); >>> } >>> >>> static void adjust_tx_list(void) >>> @@ -866,10 +873,10 @@ >>> int retval; >>> >>> /* Grab the MAC address in the MAC */ >>> - *(u32 *) (&(dev->dev_addr[0])) = bfin_read_EMAC_ADDRLO(); >>> - *(u16 *) (&(dev->dev_addr[4])) = (u16) bfin_read_EMAC_ADDRHI(); >>> + *(u32 *) (&(dev->dev_addr[0])) = cpu_to_le32(bfin_read_EMAC_ADDRLO()); >>> + *(u16 *) (&(dev->dev_addr[4])) = cpu_to_le16((u16) bfin_read_EMAC_ADDRHI()); >> Try something like this: >> >> @@ -483,9 +487,12 @@ >> >> void setup_mac_addr(u8 * mac_addr) >> { >> + u32 addr_low = le32_to_cpu(*(__le32 *) & mac_addr[0]); >> + u16 addr_hi = le16_to_cpu(*(__le16 *) & mac_addr[4]); >> + >> - /* this depends on a little-endian machine */ >> - bfin_write_EMAC_ADDRLO(*(u32 *) & mac_addr[0]); >> - bfin_write_EMAC_ADDRHI(*(u16 *) & mac_addr[4]); >> + bfin_write_EMAC_ADDRLO(addr_low); >> + bfin_write_EMAC_ADDRHI(addr_hi); >> } >> >> static void adjust_tx_list(void) >> @@ -866,10 +873,10 @@ >> int retval; >> >> /* Grab the MAC address in the MAC */ >> - *(u32 *) (&(dev->dev_addr[0])) = bfin_read_EMAC_ADDRLO(); >> - *(u16 *) (&(dev->dev_addr[4])) = (u16) bfin_read_EMAC_ADDRHI(); >> + *(__le32 *) (&(dev->dev_addr[0])) = cpu_to_le32(bfin_read_EMAC_ADDRLO()); >> + *(__le16 *) (&(dev->dev_addr[4])) = cpu_to_le16((u16) bfin_read_EMAC_ADDRHI()); >> > > Thanks a lot, Michael. > > I got a generic question about this endianess check. When should use it > in a driver or something else? I grep it in the driver/net/ > > --- > drivers/net/e100.c: ns->tx_window_errors += le32_to_cpu(s->tx_late_collisions); > drivers/net/e100.c: ns->tx_carrier_errors += le32_to_cpu(s->tx_lost_crs); > drivers/net/e100.c: ns->tx_fifo_errors += le32_to_cpu(s->tx_underruns); > drivers/net/e100.c: ns->tx_errors += le32_to_cpu(s->tx_max_collisions) + > drivers/net/e100.c: le32_to_cpu(s->tx_lost_crs); > drivers/net/e100.c: ns->rx_length_errors += le32_to_cpu(s->rx_short_frame_errors) + > drivers/net/e100.c: ns->rx_crc_errors += le32_to_cpu(s->rx_crc_errors); > drivers/net/e100.c: ns->rx_frame_errors += le32_to_cpu(s->rx_alignment_errors); > drivers/net/e100.c: ns->rx_over_errors += le32_to_cpu(s->rx_overrun_errors); > drivers/net/e100.c: ns->rx_fifo_errors += le32_to_cpu(s->rx_overrun_errors); > drivers/net/e100.c: ns->rx_missed_errors += le32_to_cpu(s->rx_resource_errors); > drivers/net/e100.c: ns->rx_errors += le32_to_cpu(s->rx_crc_errors) + > drivers/net/e100.c: le32_to_cpu(s->rx_alignment_errors) + > drivers/net/e100.c: le32_to_cpu(s->rx_short_frame_errors) + > drivers/net/e100.c: le32_to_cpu(s->rx_cdt_errors); > drivers/net/e100.c: nic->tx_deferred += le32_to_cpu(s->tx_deferred); > drivers/net/e100.c: le32_to_cpu(s->tx_single_collisions); > drivers/net/e100.c: le32_to_cpu(s->tx_multiple_collisions); > drivers/net/e100.c: nic->tx_fc_pause += le32_to_cpu(s->fc_xmt_pause); > drivers/net/e100.c: nic->rx_fc_pause += le32_to_cpu(s->fc_rcv_pause); > drivers/net/e100.c: le32_to_cpu(s->fc_rcv_unsupported); > drivers/net/e100.c: le32_to_cpu(cb->u.tcb.tbd.buf_addr), > drivers/net/e100.c: le32_to_cpu(cb->u.tcb.tbd.buf_addr), > --- > > Normally, it is used to protect some rx/tx status flags or dma buf addr. > > Any guide line for this leXX_to_cpu usage?
It has to be used when accessing any data structure stored in RAM that the device will access and where byte order is significant. cpu_to_le32 when writing to the RAM, le32_to_cpu when reading it. (or le16, etc. if needed).
-- Robert Hancock Saskatoon, SK, Canada To email, remove "nospam" from hancockr@nospamshaw.ca Home Page: http://www.roberthancock.com/
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