If the platform or bus driver failed to setup a dma_mask, but the hardware advertises support for DMA, before DMA would be enabled in dwc2, but disabled in the usb core, making all connectivity break. With this commit, the dwc2 driver will emit a warning and fall back to slave mode in this case. Note that since commit 642f2ec (staging: dwc2: Fix dma-enabled platform devices using a default dma_mask) the platform bindings make sure a DMA mask is always present, but having this check here anyway is probably a good from a defensive programming standpoint (in case of changes to platform.c or addition of new glue layers). Signed-off-by: Matthijs Kooijman <matthijs@xxxxxxxx> --- drivers/staging/dwc2/hcd.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/drivers/staging/dwc2/hcd.c b/drivers/staging/dwc2/hcd.c index 8cbdbd9..4791d81 100644 --- a/drivers/staging/dwc2/hcd.c +++ b/drivers/staging/dwc2/hcd.c @@ -2740,6 +2740,15 @@ int dwc2_hcd_init(struct dwc2_hsotg *hsotg, int irq, /* Validate parameter values */ dwc2_set_parameters(hsotg, params); + /* Check if the bus driver or platform code has setup a dma_mask */ + if (hsotg->core_params->dma_enable > 0 && + hsotg->dev->dma_mask == NULL) { + dev_warn(hsotg->dev, + "dma_mask not set, disabling DMA\n"); + hsotg->core_params->dma_enable = 0; + hsotg->core_params->dma_desc_enable = 0; + } + /* Set device flags indicating whether the HCD supports DMA */ if (hsotg->core_params->dma_enable > 0) { if (dma_set_mask(hsotg->dev, DMA_BIT_MASK(32)) < 0) -- 1.8.3.rc1 -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html