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  • Al Cooper's avatar
    phy: usb: EHCI DMA may lose a burst of DMA data for 7255xA0 family · dc9aa43c
    Al Cooper authored
    
    
    When the EHCI controller received a 512 byte USB packet that
    had to be broken into 2 256 byte bursts across the SCB bus AND
    there was a following 512 byte USB packet, the second burst of
    data from the first packet was sometimes being lost. If the
    burst size was changed to 128 bytes via the EBR_SCB_SIZE field
    in the USB_CTRL_EBRIDGE register we'd see the 4th 128 byte burst
    of the first packet being lost. This problem became much worse
    if other threads were running that accessed memory, like a memcpy
    test. Setting the EBR_SCB_SIZE to 512, which prevents breaking
    the EHCI USB packet (max size of 512 bytes) into bursts, fixed
    the problem.
    Signed-off-by: default avatarAl Cooper <alcooperx@gmail.com>
    Reviewed-by: default avatarFlorian Fainelli <f.fainelli@gmail.com>
    Signed-off-by: default avatarKishon Vijay Abraham I <kishon@ti.com>
    dc9aa43c
phy-brcm-usb-init.c 32.7 KB