The data read from the SKIPMAP registers is not immediately available after writing and the driver panics when a packet is enqueued from the interrupt handler. This patch adds an ndelay(195) before these registers are read (delay value mentioned in section 15.1.1.3 of the ISP1760 data sheet). Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx> Acked-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> --- drivers/usb/host/isp1760-hcd.c | 14 ++++++++++++++ 1 files changed, 14 insertions(+), 0 deletions(-) diff --git a/drivers/usb/host/isp1760-hcd.c b/drivers/usb/host/isp1760-hcd.c index 8ee2f41..8d57182 100644 --- a/drivers/usb/host/isp1760-hcd.c +++ b/drivers/usb/host/isp1760-hcd.c @@ -819,6 +819,13 @@ static void enqueue_an_ATL_packet(struct usb_hcd *hcd, struct isp1760_qh *qh, u32 atl_regs, payload; u32 buffstatus; + /* + * When this function is called from the interrupt handler to enqueue + * a follow-up packet, the SKIP register gets written and read back + * almost immediately. With ISP1761, this register requires a delay of + * 195ns between a write and subsequent read (see section 15.1.1.3). + */ + ndelay(195); skip_map = isp1760_readl(hcd->regs + HC_ATL_PTD_SKIPMAP_REG); BUG_ON(!skip_map); @@ -853,6 +860,13 @@ static void enqueue_an_INT_packet(struct usb_hcd *hcd, struct isp1760_qh *qh, u32 int_regs, payload; u32 buffstatus; + /* + * When this function is called from the interrupt handler to enqueue + * a follow-up packet, the SKIP register gets written and read back + * almost immediately. With ISP1761, this register requires a delay of + * 195ns between a write and subsequent read (see section 15.1.1.3). + */ + ndelay(195); skip_map = isp1760_readl(hcd->regs + HC_INT_PTD_SKIPMAP_REG); BUG_ON(!skip_map); -- 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
