Messages in this thread | | | From | Felipe Balbi <> | Subject | Re: [PATCH] xhci: Use ffs() to find page size in xhci_mem_init() | Date | Thu, 07 Feb 2019 11:06:00 +0200 |
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Hi,
Mathias Nyman <mathias.nyman@linux.intel.com> writes: > On 07.02.2019 02:03, Andrey Smirnov wrote: >> Get page size order using ffs() instead of open coding it with a loop. >> >> Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com> >> Cc: Mathias Nyman <mathias.nyman@intel.com> >> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> >> Cc: linux-usb@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().
-- balbi [unhandled content-type:application/pgp-signature]
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