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Below is a description of a possible problematic
sequence. CPU-A is sending a frame and CPU-B handles
the interrupt that indicates the frame was sent. CPU-B
reads an invalid value of tx_packet_sent.
CPU-A CPU-B
----- -----
nps_enet_send_frame
.
.
tx_skb = skb
tx_packet_sent = true
order HW to start tx
.
.
HW complete tx
------> get tx complete interrupt
.
.
if(tx_packet_sent == true)
handle tx_skb
end memory transaction
(tx_packet_sent actually
written)
Furthermore there is a dependency between tx_skb and tx_packet_sent.
There is no assurance that tx_skb contains a valid pointer at CPU B
when it sees tx_packet_sent == true.
Solution:
Initialize tx_skb to NULL and use it to indicate that packet was sent,
in this way tx_packet_sent can be removed.
Add a write memory barrier after setting tx_skb in order to make sure
that it is valid before HW is informed and IRQ is fired.
Fixed sequence will be:
CPU-A CPU-B
----- -----
tx_skb = skb
wmb()
.
.
order HW to start tx
.
.
HW complete tx
------> get tx complete interrupt
.
.
if(tx_skb != NULL)
handle tx_skb
tx_skb = NULL
Signed-off-by: Elad Kanfi <eladkan@mellanox.com>
Acked-by: Noam Camus <noamca@mellanox.com>
Acked-by: Gilad Ben-Yossef <giladby@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Since ezchip network driver is written with big endian EZChip platform it
is necessary to add support for little endian architecture.
The first issue is that the order of the bits in a bit field is
implementation specific. So all the bit fields are removed.
Named constants are used to access necessary fields.
And the second one is that network byte order is big endian.
For example, data on ethernet is transmitted with most-significant
octet (byte) first. So in case of little endian architecture
it is important to swap data byte order when we read it from
register. In case of unaligned access we can use "get_unaligned_be32"
and in other case we can use function "ioread32_rep" which reads all
data from register and works either with little endian or big endian
architecture.
And then when we are going to write data to register we need to restore
byte order using the function "put_unaligned_be32" in case of
unaligned access and in other case "iowrite32_rep".
The last little fix is a space between type and pointer to observe
coding style.
Signed-off-by: Lada Trimasova <ltrimas@synopsys.com>
Cc: Alexey Brodkin <abrodkin@synopsys.com>
Cc: Noam Camus <noamc@ezchip.com>
Cc: Tal Zilcer <talz@ezchip.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
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When interrupt is received we read directly from control
register for RX/TX instead of reading cause register
since this register fails to indicate TX done when
TX interrupt is "edge mode".
Signed-off-by: Noam Camus <noamc@ezchip.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Simple LAN device for debug or management purposes.
Device supports interrupts for RX and TX(completion).
Device does not have DMA ability.
Signed-off-by: Noam Camus <noamc@ezchip.com>
Signed-off-by: Tal Zilcer <talz@ezchip.com>
Acked-by: Alexey Brodkin <abrodkin@synopsys.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Elad Kanfi
Lada Trimasova
Noam Camus