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SubjectRe: [PATCH try#2] Blackfin ethernet driver: on chip ethernet MAC controller driver
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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