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USB: isp1760: Add a delay before reading the SKIPMAP registers in isp1760-hcd.c

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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>
This commit is contained in:
Catalin Marinas 2009-03-23 12:38:16 +00:00 committed by Greg Kroah-Hartman
parent b7af0bb268
commit e6bdfe36e5
1 changed files with 14 additions and 0 deletions
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14
drivers/usb/host/isp1760-hcd.c
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@ -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);