Hi,

Thinh Nguyen <Thinh.Nguyen@synopsys.com> writes:
> From: Yu Chen <chenyu56@huawei.com>
> From: John Stultz <john.stultz@linaro.org>
>
> According to the programming guide, to switch mode for DRD controller,
> the driver needs to do the following.
>
> To switch from device to host:
> 1. Reset controller with GCTL.CoreSoftReset
> 2. Set GCTL.PrtCapDir(host mode)
> 3. Reset the host with USBCMD.HCRESET
> 4. Then follow up with the initializing host registers sequence
>
> To switch from host to device:
> 1. Reset controller with GCTL.CoreSoftReset
> 2. Set GCTL.PrtCapDir(device mode)
> 3. Reset the device with DCTL.CSftRst
> 4. Then follow up with the initializing registers sequence
>
> Currently we're missing step 1) to do GCTL.CoreSoftReset and step 3) of

we're not really missing, it was a deliberate choice :-) The only reason
why we need the soft reset is because host and gadget registers map to
the same physical space within dwc3 core. If we cache and restore the
affected registers, we're good ;-)

IMHO, that's a better compromise than doing a full soft reset.

> @@ -40,6 +41,8 @@
>  
>  #define DWC3_DEFAULT_AUTOSUSPEND_DELAY	5000 /* ms */
>  
> +static DEFINE_MUTEX(mode_switch_lock);

there are several platforms which more than one DWC3 instance. Sure this
won't break on such systems?

-- 
balbi