Re: [PATCH v3 03/12] usb: ehci-hcd: notify phy when connect change

Dear Alan Stern,

On Tue, 5 Jun 2012, Marek Vasut wrote:

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+			/* FIXME:
+			 * - it does not work for multi-phy ehci
+			 * - the best place is after debounce, but I 

can't get

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+			 *   phy there
+			 */
+			if ((pstatus & PORT_CSC) && ehci->transceiver) {

Do the tests in the opposite order and add "unlikely":
			if (unlikely(ehci->transceiver &&
			
					(pstatus & PORT_CSC)) {

That way it will fail more quickly on systems where it doesn't apply or
for unaffected ports.

Does this unlikely() have any effect on ARM/MIPS/PPC, where this chipidea
IP is used ? Or is there some x86 device sporting this IP too?

I don't know what unlikely() does on architectures other than x86.

It should be optimized out to nothing on anything else but x86. On x86 it is a 
hint for the branch predictor. Or that's what I believe it is.

And
I haven't heard of any x86 systems that would need to use this code.

On the other hand, port-status changes don't occur very frequently.  A
little time penalty one way or the other won't make much difference.

I'm not opposed, just curious :)

Alan Stern

Best regards,
Marek Vasut
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