On 07.02.2019 12:58, Felipe Balbi wrote:
Hi,
Mathias Nyman <mathias.ny...@intel.com> writes:
Get page size order using ffs() instead of open coding it with a loop.
Signed-off-by: Andrey Smirnov <andrew.smir...@gmail.com>
Cc: Mathias Nyman <mathias.ny...@intel.com>
Cc: Greg Kroah-Hartman <gre...@linuxfoundation.org>
Cc: linux-...@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
---
drivers/usb/host/xhci-mem.c | 6 +-----
1 file changed, 1 insertion(+), 5 deletions(-)
diff --git a/drivers/usb/host/xhci-mem.c b/drivers/usb/host/xhci-mem.c
index 36a3eb8849f1..44b43c3d819f 100644
--- a/drivers/usb/host/xhci-mem.c
+++ b/drivers/usb/host/xhci-mem.c
@@ -2362,11 +2362,7 @@ int xhci_mem_init(struct xhci_hcd *xhci, gfp_t flags)
page_size = readl(&xhci->op_regs->page_size);
xhci_dbg_trace(xhci, trace_xhci_dbg_init,
"Supported page size register = 0x%x", page_size);
- for (i = 0; i < 16; i++) {
- if ((0x1 & page_size) != 0)
- break;
- page_size = page_size >> 1;
- }
+ i = ffs(page_size);
if (i < 16)
xhci_dbg_trace(xhci, trace_xhci_dbg_init,
"Supported page size of %iK", (1 << (i+12)) / 1024);
Hi
using ffs() is a welcome change, but it will give different a result than the
loop.
*old loop
valid page_size value if i < 16
*ffs()
valid page_size value if i >= 1 and i < 17
off-by-one, just use i = ffs() - 1. Or use __ffs().
and handle the page_size == 0 case.
Can it be zero in real life, or are you protecting against academic
possibility that's never going to happen in HW?
whole page_size check is not really doing much, just printing out
different debug messages.
-Mathias
