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usb: host: xhci: use __ffs() instead of hardcoding shift

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__ffs() can tell us which is the SEGMENT_SHIFT value
to be used. This will prevent problems when users are
too fast and don't pay attention to the need of fixing
the Shift after changing TRBS_PER_SEGMENT.

Signed-off-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
This commit is contained in:
Felipe Balbi 2012-01-27 16:19:15 +02:00 committed by Sarah Sharp
parent f99298bfa7
commit 8d3709f3dd
1 changed files with 1 additions and 4 deletions
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5
drivers/usb/host/xhci.h
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@ -1223,10 +1223,7 @@ union xhci_trb {
/* Allow two commands + a link TRB, along with any reserved command TRBs */
#define MAX_RSVD_CMD_TRBS (TRBS_PER_SEGMENT - 3)
#define SEGMENT_SIZE (TRBS_PER_SEGMENT*16)
/* SEGMENT_SHIFT should be log2(SEGMENT_SIZE).
* Change this if you change TRBS_PER_SEGMENT!
*/
#define SEGMENT_SHIFT 10
#define SEGMENT_SHIFT (__ffs(SEGMENT_SIZE))
/* TRB buffer pointers can't cross 64KB boundaries */
#define TRB_MAX_BUFF_SHIFT 16
#define TRB_MAX_BUFF_SIZE (1 << TRB_MAX_BUFF_SHIFT)