USB: isp1760: Add a delay before reading the SKIPMAP registers in isp1760-hcd.c
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@arm.com>
Acked-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/usb/host/isp1760-hcd.c b/drivers/usb/host/isp1760-hcd.c
index 3172c0f..cd07ea3 100644
--- a/drivers/usb/host/isp1760-hcd.c
+++ b/drivers/usb/host/isp1760-hcd.c
@@ -819,6 +819,13 @@
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 @@
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);