> From: Of Roger Quadros
> With u-boot 2013.10, USB devices are sometimes not detected
> on OMAP4 Panda. To make us independent of what bootloader does
> with the USB Host module, we must RESET it to get it to a known
> good state. This patch Soft RESETs the USB Host module.
...
> +++ b/drivers/mfd/omap-usb-host.c
> @@ -43,14 +43,18 @@
> /* UHH Register Set */
> #define OMAP_UHH_REVISION (0x00)
> #define OMAP_UHH_SYSCONFIG (0x10)
> -#define OMAP_UHH_SYSCONFIG_MIDLEMODE (1 << 12)
> +#define OMAP_UHH_SYSCONFIG_MIDLEMASK (3 << 12)
> +#define OMAP_UHH_SYSCONFIG_MIDLESHIFT (12)
(tab/space issue)
Wouldn't it be clearer to define these in the opposite order with:
+#define OMAP_UHH_SYSCONFIG_MIDLEMASK (3 << OMAP_UHH_SYSCONFIG_MIDLESHIFT)
...
> +static void omap_usbhs_rev1_reset(struct device *dev)
> +{
> + struct usbhs_hcd_omap *omap = dev_get_drvdata(dev);
> + u32 reg;
> + unsigned long timeout;
> +
> + reg = usbhs_read(omap->uhh_base, OMAP_UHH_SYSCONFIG);
> +
> + /* Soft Reset */
> + usbhs_write(omap->uhh_base, OMAP_UHH_SYSCONFIG,
> + reg | OMAP_UHH_SYSCONFIG_SOFTRESET);
> +
> + timeout = jiffies + msecs_to_jiffies(100);
> + while (!(usbhs_read(omap->uhh_base, OMAP_UHH_SYSSTATUS)
> + & OMAP_UHH_SYSSTATUS_RESETDONE)) {
> + cpu_relax();
> +
> + if (time_after(jiffies, timeout)) {
> + dev_err(dev, "Soft RESET operation timed out\n");
> + break;
> + }
> + }
> +
> + /* Set No-Standby */
> + reg &= ~OMAP_UHH_SYSCONFIG_MIDLEMASK;
> + reg |= OMAP_UHH_SYSCONFIG_MIDLE_NOSTANDBY
> + << OMAP_UHH_SYSCONFIG_MIDLESHIFT;
> +
> + /* Set No-Idle */
> + reg &= ~OMAP_UHH_SYSCONFIG_SIDLEMASK;
> + reg |= OMAP_UHH_SYSCONFIG_SIDLE_NOIDLE
> + << OMAP_UHH_SYSCONFIG_SIDLESHIFT;
Why not pass in the mask and value and avoid replicating the
entire function. I can't see any other significant differences,
the udelay(2) won't be significant.
I'm not sure of the context this code runs in, but if the reset
is likely to take a significant portion of the 100ms timeout
period, why not just sleep for a few ms between status polls.
David
--
To unsubscribe from this list: send the line "unsubscribe linux-usb" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
