diff options
Diffstat (limited to 'drivers/usb/host/uhci-hcd.c')
| -rw-r--r-- | drivers/usb/host/uhci-hcd.c | 51 |
1 files changed, 29 insertions, 22 deletions
diff --git a/drivers/usb/host/uhci-hcd.c b/drivers/usb/host/uhci-hcd.c index e0d4c2358b3..49b9d390b95 100644 --- a/drivers/usb/host/uhci-hcd.c +++ b/drivers/usb/host/uhci-hcd.c @@ -92,6 +92,34 @@ static void suspend_rh(struct uhci_hcd *uhci, enum uhci_rh_state new_state); static void wakeup_rh(struct uhci_hcd *uhci); static void uhci_get_current_frame_number(struct uhci_hcd *uhci); +/* + * Calculate the link pointer DMA value for the first Skeleton QH in a frame. + */ +static __le32 uhci_frame_skel_link(struct uhci_hcd *uhci, int frame) +{ + int skelnum; + + /* + * The interrupt queues will be interleaved as evenly as possible. + * There's not much to be done about period-1 interrupts; they have + * to occur in every frame. But we can schedule period-2 interrupts + * in odd-numbered frames, period-4 interrupts in frames congruent + * to 2 (mod 4), and so on. This way each frame only has two + * interrupt QHs, which will help spread out bandwidth utilization. + * + * ffs (Find First bit Set) does exactly what we need: + * 1,3,5,... => ffs = 0 => use skel_int2_qh = skelqh[8], + * 2,6,10,... => ffs = 1 => use skel_int4_qh = skelqh[7], etc. + * ffs >= 7 => not on any high-period queue, so use + * skel_int1_qh = skelqh[9]. + * Add in UHCI_NUMFRAMES to insure at least one bit is set. + */ + skelnum = 8 - (int) __ffs(frame | UHCI_NUMFRAMES); + if (skelnum <= 1) + skelnum = 9; + return UHCI_PTR_QH | cpu_to_le32(uhci->skelqh[skelnum]->dma_handle); +} + #include "uhci-debug.c" #include "uhci-q.c" #include "uhci-hub.c" @@ -631,32 +659,11 @@ static int uhci_start(struct usb_hcd *hcd) /* * Fill the frame list: make all entries point to the proper * interrupt queue. - * - * The interrupt queues will be interleaved as evenly as possible. - * There's not much to be done about period-1 interrupts; they have - * to occur in every frame. But we can schedule period-2 interrupts - * in odd-numbered frames, period-4 interrupts in frames congruent - * to 2 (mod 4), and so on. This way each frame only has two - * interrupt QHs, which will help spread out bandwidth utilization. */ for (i = 0; i < UHCI_NUMFRAMES; i++) { - int irq; - - /* - * ffs (Find First bit Set) does exactly what we need: - * 1,3,5,... => ffs = 0 => use skel_int2_qh = skelqh[8], - * 2,6,10,... => ffs = 1 => use skel_int4_qh = skelqh[7], etc. - * ffs >= 7 => not on any high-period queue, so use - * skel_int1_qh = skelqh[9]. - * Add UHCI_NUMFRAMES to insure at least one bit is set. - */ - irq = 8 - (int) __ffs(i + UHCI_NUMFRAMES); - if (irq <= 1) - irq = 9; /* Only place we don't use the frame list routines */ - uhci->frame[i] = UHCI_PTR_QH | - cpu_to_le32(uhci->skelqh[irq]->dma_handle); + uhci->frame[i] = uhci_frame_skel_link(uhci, i); } /* |