On 01/08/2014 01:23 AM, Greg KH wrote: > On Mon, Jan 06, 2014 at 10:10:41AM +0800, Peter Chen wrote: >> According to Freescale imx28 Errata, "ENGR119653 USB: ARM to USB >> register error issue", All USB register write operations must >> use the ARM SWP instruction. So, we implement a special ehci_write >> for imx28. >> >> Discussion for it at below: >> http://marc.info/?l=linux-usb&m=137996395529294&w=2 >> >> Signed-off-by: Peter Chen <peter.c...@freescale.com> >> Acked-by: Alan Stern <st...@rowland.harvard.edu> >> Signed-off-by: Marc Kleine-Budde <m...@pengutronix.de> >> Tested-by: Marc Kleine-Budde <m...@pengutronix.de> >> --- >> drivers/usb/host/ehci.h | 18 +++++++++++++++++- >> 1 files changed, 17 insertions(+), 1 deletions(-) >> >> diff --git a/drivers/usb/host/ehci.h b/drivers/usb/host/ehci.h >> index c35a6e2b..e26099b 100644 >> --- a/drivers/usb/host/ehci.h >> +++ b/drivers/usb/host/ehci.h >> @@ -225,6 +225,7 @@ struct ehci_hcd { /* one per >> controller */ >> unsigned has_synopsys_hc_bug:1; /* Synopsys HC */ >> unsigned frame_index_bug:1; /* MosChip (AKA NetMos) */ >> unsigned need_oc_pp_cycle:1; /* MPC834X port power */ >> + unsigned imx28_write_fix:1; /* For Freescale i.MX28 */ >> >> /* required for usb32 quirk */ >> #define OHCI_CTRL_HCFS (3 << 6) >> @@ -728,6 +729,18 @@ static inline unsigned int ehci_readl(const struct >> ehci_hcd *ehci, >> #endif >> } >> >> +#ifdef CONFIG_SOC_IMX28 >> +static inline void imx28_ehci_writel(const unsigned int val, >> + volatile __u32 __iomem *addr) >> +{ >> + __asm__ ("swp %0, %0, [%1]" : : "r"(val), "r"(addr)); >> +} >> +#else >> +static inline void imx28_ehci_writel(const unsigned int val, >> + volatile __u32 __iomem *addr) >> +{ >> +} >> +#endif >> static inline void ehci_writel(const struct ehci_hcd *ehci, >> const unsigned int val, __u32 __iomem *regs) >> { >> @@ -736,7 +749,10 @@ static inline void ehci_writel(const struct ehci_hcd >> *ehci, >> writel_be(val, regs) : >> writel(val, regs); >> #else >> - writel(val, regs); >> + if (IS_ENABLED(CONFIG_SOC_IMX28) && ehci->imx28_write_fix) >> + imx28_ehci_writel(val, regs); >> + else >> + writel(val, regs); >> #endif > > This IS_ENABLED() isn't needed at all, so please remove it.
It's an optimisation for the hot path, if kernel isn't build for a mx28 the newly added if() is completely optimized out. The same argument applies to the next patch. Marc -- Pengutronix e.K. | Marc Kleine-Budde | Industrial Linux Solutions | Phone: +49-231-2826-924 | Vertretung West/Dortmund | Fax: +49-5121-206917-5555 | Amtsgericht Hildesheim, HRA 2686 | http://www.pengutronix.de |
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