From: Dinh Nguyen <dinguyen@xxxxxxxxxx> Even though the IP supports Descriptor DMA mode, it does not support SPLIT transactions in this mode. So the driver, in its currently form, will not support LS/FS devices when connected to a HS Hub if Descriptor DMA mode is enabled. So we disable descriptor dma mode by default and a provide device tree property for users to enable it if they really want to. Signed-off-by: Dinh Nguyen <dinguyen@xxxxxxxxxx> --- v2: - Reworked patch to disable descriptor dma by default - Removed unneeded helper variable - Reword patch commit header --- drivers/usb/dwc2/platform.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/drivers/usb/dwc2/platform.c b/drivers/usb/dwc2/platform.c index eaba547..cc50d00 100644 --- a/drivers/usb/dwc2/platform.c +++ b/drivers/usb/dwc2/platform.c @@ -134,6 +134,16 @@ static int dwc2_driver_probe(struct platform_device *dev) /* Default all params to autodetect */ dwc2_set_all_params(&defparams, -1); params = &defparams; + + /* + * Disable descriptor dma mode by default as the HW can support + * it, but does not support it for SPLIT transactions. One can + * use the device tree property "dma-desc-enable", if one really + * wants to enable descriptor dma mode. + */ + defparams.dma_desc_enable = 0; + of_property_read_u32(dev->dev.of_node, "dma-desc-enable", + &defparams.dma_desc_enable); } hsotg = devm_kzalloc(&dev->dev, sizeof(*hsotg), GFP_KERNEL); -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
