* Catalin Marinas | 2009-03-23 12:38:16 [+0000]: >My datasheet for ISP1760 doesn't have a table 95 in section 14.1.3 (but >in the next section). However the ISP1761 data sheet has a section >15.1.1.3 mentioning the 195ns delay for the EHCI registers. > >> So after long thinking I'm fine with this patch. Please update your >> comment and add _why_ this delay is required. > >That's an updated patch: Thanks for the patch. If this solved your problem than I'm fine with it. Acked-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> The "other" EHCI registers are touched in the hub code (isp1760_hub_status_data(), isp1760_hub_control()). It looks like they are not causing the problem right now. I try to add special read/write routine which adds the delay prior reading them..... >Add a delay before reading the SKIPMAP registers in isp1760-hcd.c > >From: Catalin Marinas <catalin.marinas@xxxxxxx> > >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> >--- > 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); > > >Thanks. > >-- >Catalin -- 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
