When a frame is sent using FDMA, the skb is mapped and then the mapped
address is given to an tx dcb that is different than the last used tx
dcb. Once the HW finish with this frame, it would generate an interrupt
and then the dcb can be reused and memory can be freed. For each dcb
there is an dcb buf that contains some meta-data(is used by PTP, is
it free). There is 1 to 1 relationship between dcb and dcb_buf.
The following issue was observed. That sometimes after changing the MTU
to allocate new tx dcbs and dcbs_buf, two frames were not
transmitted. The frames were not transmitted because when reloading the
tx dcbs, it was always presuming to use the first dcb but that was not
always happening. Because it could be that the last tx dcb used before
changing MTU was first dcb and then when it tried to get the next dcb it
would take dcb 1 instead of 0. Because it is supposed to take a
different dcb than the last used one. This can be fixed simply by
changing tx->last_in_use to -1 when the fdma is disabled to reload the
new dcb and dcbs_buff.
But there could be a different issue. For example, right after the frame
is sent, the MTU is changed. Now all the dcbs and dcbs_buf will be
cleared. And now get the interrupt from HW that it finished with the
frame. So when we try to clear the skb, it is not possible because we
lost all the dcbs_buf.
The solution here is to stop replacing the tx dcbs and dcbs_buf when
changing MTU because the TX doesn't care what is the MTU size, it is
only the RX that needs this information.
Fixes: 2ea1cbac26 ("net: lan966x: Update FDMA to change MTU.")
Signed-off-by: Horatiu Vultur <horatiu.vultur@microchip.com>
Link: https://lore.kernel.org/r/20221021090711.3749009-1-horatiu.vultur@microchip.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
We tell driver developers to always pass NAPI_POLL_WEIGHT
as the weight to netif_napi_add(). This may be confusing
to newcomers, drop the weight argument, those who really
need to tweak the weight can use netif_napi_add_weight().
Acked-by: Marc Kleine-Budde <mkl@pengutronix.de> # for CAN
Link: https://lore.kernel.org/r/20220927132753.750069-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
The smatch found the following warning:
drivers/net/ethernet/microchip/lan966x/lan966x_fdma.c:736 lan966x_fdma_reload()
warn: 'rx_dcbs' was already freed.
This issue can happen when changing the MTU on one of the ports and once
the RX buffers are allocated and then the TX buffer allocation fails.
In that case the RX buffers should not be restore. This fix this issue
such that the RX buffers will not be restored if the TX buffers failed
to be allocated.
Fixes: 2ea1cbac26 ("net: lan966x: Update FDMA to change MTU.")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Horatiu Vultur <horatiu.vultur@microchip.com>
Link: https://lore.kernel.org/r/20220511204059.2689199-1-horatiu.vultur@microchip.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
When changing the MTU, it is required to change also the size of the
DBs. In case those frames will arrive to CPU.
Signed-off-by: Horatiu Vultur <horatiu.vultur@microchip.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Ethernet frames can be extracted or injected to or from the device's
DDR memory. There is one channel for injection and one channel for
extraction. Each of these channels contain a linked list of DCBs which
contains DB. The DCB contains only 1 DB for both the injection and
extraction. Each DB contains a frame. Every time when a frame is received
or transmitted an interrupt is generated.
It is not possible to use both the FDMA and the manual
injection/extraction of the frames. Therefore the FDMA has priority over
the manual because of better performance values.
FDMA:
iperf -c 192.168.1.1
[ 5] 0.00-10.02 sec 420 MBytes 352 Mbits/sec 0 sender
[ 5] 0.00-10.03 sec 420 MBytes 351 Mbits/sec receiver
iperf -c 192.168.1.1 -R
[ 5] 0.00-10.01 sec 528 MBytes 442 Mbits/sec 0 sender
[ 5] 0.00-10.00 sec 524 MBytes 440 Mbits/sec receiver
Manual:
iperf -c 192.168.1.1
[ 5] 0.00-10.02 sec 93.8 MBytes 78.5 Mbits/sec 0 sender
[ 5] 0.00-10.03 sec 93.8 MBytes 78.4 Mbits/sec receiver
ipers -c 192.168.1.1 -R
[ 5] 0.00-10.03 sec 121 MBytes 101 Mbits/sec 0 sender
[ 5] 0.00-10.01 sec 118 MBytes 99.0 Mbits/sec receiver
Signed-off-by: Horatiu Vultur <horatiu.vultur@microchip.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
