phy: usb: EHCI DMA may lose a burst of DMA data for 7255xA0 family
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: Al Cooper <alcooperx@gmail.com> Reviewed-by: Florian Fainelli <f.fainelli@gmail.com> Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
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