Hi David,
On 11/29/2013 03:17 PM, David Laight wrote:
>> 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)
Weird, original code seems to use a tab instead of space after #define.
>
> Wouldn't it be clearer to define these in the opposite order with:
> +#define OMAP_UHH_SYSCONFIG_MIDLEMASK (3 << OMAP_UHH_SYSCONFIG_MIDLESHIFT)
Right.
>
> ...
>> +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();
You mean use msleep(1) here instead of cpu_relax()?
Shouldn't be a problem IMO, but can you please tell me why that is better
as the reset seems to complete usually in the first iteration.
>> +
>> + 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.
OK, I can pass the mask and value, but still there is a difference
in the way reset complete is checked between v1 and v2. But that
be in omap_usbhs_softreset() and the individual reset functions can be
replaced by a single omap_usbhs_set_sysconfig().
It seems the udelay() is not required for the USB Host module, so I'll
get rid of that.
>
> 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.
covered in the related code above.
cheers,
-roger
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