• Troy Kisky's avatar
    ARM: dts: imx6qdl-sabrelite: use GPIO_6 for FEC interrupt. · 6261c4c8
    Troy Kisky authored
    This works around a hardware bug.
    From "Chip Errata for the i.MX 6Dual/6Quad"
    
    ERR006687 ENET: Only the ENET wake-up interrupt request can wake the
    system from Wait mode.
    
    The ENET block generates many interrupts. Only one of these interrupt lines
    is connected to the General Power Controller (GPC) block, but a logical OR
    of all of the ENET interrupts is connected to the General Interrupt Controller
    (GIC). When the system enters Wait mode, a normal RX Done or TX Done does not
    wake up the system because the GPC cannot see this interrupt. This impacts
    performance of the ENET block because its interrupts are serviced only when
    the chip exits Wait mode due to an interrupt from some other wake-up source.
    
    Before this patch, ping times of a Sabre Lite board are quite
    random:
    ping 192.168.0.13 -i.5 -c5
    PING 192.168.0.13 (192.168.0.13) 56(84) bytes of data.
    64 bytes from 192.168.0.13: icmp_req=1 ttl=64 time=15.7 ms
    64 bytes from 192.168.0.13: icmp_req=2 ttl=64 time=14.4 ms
    64 bytes from 192.168.0.13: icmp_req=3 ttl=64 time=13.4 ms
    64 bytes from 192.168.0.13: icmp_req=4 ttl=64 time=12.4 ms
    64 bytes from 192.168.0.13: icmp_req=5 ttl=64 time=11.4 ms
    
    === 192.168.0.13 ping statistics ===
    5 packets transmitted, 5 received, 0% packet loss, time 2004ms
    rtt min/avg/max/mdev = 11.431/13.501/15.746/1.508 ms
    ____________________________________________________
    After this patch:
    
    ping 192.168.0.13 -i.5 -c5
    PING 192.168.0.13 (192.168.0.13) 56(84) bytes of data.
    64 bytes from 192.168.0.13: icmp_req=1 ttl=64 time=0.120 ms
    64 bytes from 192.168.0.13: icmp_req=2 ttl=64 time=0.175 ms
    64 bytes from 192.168.0.13: icmp_req=3 ttl=64 time=0.169 ms
    64 bytes from 192.168.0.13: icmp_req=4 ttl=64 time=0.168 ms
    64 bytes from 192.168.0.13: icmp_req=5 ttl=64 time=0.172 ms
    
    === 192.168.0.13 ping statistics ===
    5 packets transmitted, 5 received, 0% packet loss, time 1999ms
    rtt min/avg/max/mdev = 0.120/0.160/0.175/0.026 ms
    ____________________________________________________
    
    Also, apply same change to imx6qdl-nitrogen6x.
    
    This change may not be appropriate for all boards.
    Sabre Lite uses GPIO6 as a power down output for a ov5642
    camera. As this expansion board does not yet work with mainline,
    this is not yet a conflict. It would be nice to have an alternative
    fix for boards where this is a problem.
    
    For example Sabre SD uses GPIO6 for I2C3_SDA. It also
    has long ping times currently. But cannot use this fix
    without giving up a touchscreen.
    
    Its ping times are also random.
    
    ping 192.168.0.19 -i.5 -c5
    PING 192.168.0.19 (192.168.0.19) 56(84) bytes of data.
    64 bytes from 192.168.0.19: icmp_req=1 ttl=64 time=16.0 ms
    64 bytes from 192.168.0.19: icmp_req=2 ttl=64 time=15.4 ms
    64 bytes from 192.168.0.19: icmp_req=3 ttl=64 time=14.4 ms
    64 bytes from 192.168.0.19: icmp_req=4 ttl=64 time=13.4 ms
    64 bytes from 192.168.0.19: icmp_req=5 ttl=64 time=12.4 ms
    
    === 192.168.0.19 ping statistics ---
    5 packets transmitted, 5 received, 0% packet loss, time 2003ms
    rtt min/avg/max/mdev = 12.451/14.369/16.057/1.316 ms
    Signed-off-by: default avatarTroy Kisky <troy.kisky@boundarydevices.com>
    CC: Ranjani Vaidyanathan <ra5478@freescale.com>
    Signed-off-by: default avatarShawn Guo <shawn.guo@linaro.org>
    6261c4c8
imx6qdl-sabrelite.dtsi 8.95 KB