Re: [PATCH 3/3] OMAP clock/hwmod: fix off-by-one errors

[Tony Lindgren <tony@atomide.com>]

* Pandita, Vikram <vikram.pandita@ti.com> [091117 09:50]:
> Paul
> 
> >-----Original Message-----
> >From: linux-omap-owner@vger.kernel.org [mailto:linux-omap-owner@vger.kernel.org] On Behalf Of Paul
> >Walmsley
> >Sent: Tuesday, November 17, 2009 11:39 AM
> >To: Russell King - ARM Linux
> >Cc: linux-arm-kernel@lists.infradead.org; Juha Leppänen; linux-omap@vger.kernel.org
> >Subject: Re: [PATCH 3/3] OMAP clock/hwmod: fix off-by-one errors
> <snip>
> >
> >+/**
> >+ * omap_test_timeout - busy-loop, testing a condition
> >+ * @cond: condition to test until it evaluates to true
> >+ * @timeout: maximum number of microseconds in the timeout
> >+ * @index: loop index (integer)
> >+ *
> >+ * Loop waiting for @cond to become true or until at least @timeout
> >+ * microseconds have passed.  To use, define some integer @index in the
> >+ * calling code.  After running, if @index == @timeout, then the loop has
> >+ * timed out.
> >+ */
> >+#define omap_test_timeout(cond, timeout, index)			\
> >+({								\
> >+	for (index = 0; index < timeout; index++) {		\
> >+		if (cond)					\
> >+			break;					\
> >+		udelay(1);					\
> >+	}							\
> >+})
> >+
> 
> There is a similar kind of function implemented in USB host, that returns -ETIMEDOUT
> Which makes more sense for failure case.
> 
> Maybe such a generic function for all omaps is needed.
> 
> Refer:
> drivers/usb/host/ehci-hcd.c
> static int handshake (struct ehci_hcd *ehci, void __iomem *ptr,
>                       u32 mask, u32 done, int usec)
> {
>         u32     result;
> 
>         do {
>                 result = ehci_readl(ehci, ptr);
>                 if (result == ~(u32)0)          /* card removed */
>                         return -ENODEV;
>                 result &= mask;
>                 if (result == done)
>                         return 0;
>                 udelay (1);
>                 usec--;
>         } while (usec > 0);
>         return -ETIMEDOUT;
> }
> 
> 
> > #endif /* __ARCH_ARM_MACH_OMAP_COMMON_H */

Well we need to stick to minimal changes if we plan to send this in as a fix.
Anything more complex we should do the next merge window.

Tony
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