On Thu, Apr 15, 2021 at 07:10:34AM +0000, Thinh Nguyen wrote:
Felipe Balbi wrote:
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:
- Reset controller with GCTL.CoreSoftReset
- Set GCTL.PrtCapDir(host mode)
- Reset the host with USBCMD.HCRESET
- Then follow up with the initializing host registers sequence
To switch from host to device:
- Reset controller with GCTL.CoreSoftReset
- Set GCTL.PrtCapDir(device mode)
- Reset the device with DCTL.CSftRst
- 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 ;-)
It's part of the programming model. I've already discussed with internal RTL designers. This is needed, and I've provided the discussion we had prior also. We have several different devices in the wild that need this. What is the concern?
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?
How? Am I missing something? Please let me know so I can make the change.
All data needs to be per-device, not "global for the codebase" like the way you declared this lock.
thanks,
greg k-h