Re: [PATCH v3] usb: dwc3: core: Do core softreset when switch mode

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Thinh Nguyen wrote:
> From: Yu Chen <chenyu56@xxxxxxxxxx>
> From: John Stultz <john.stultz@xxxxxxxxxx>
> 
> 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
> switching from host to device. John Stult reported a lockup issue seen
> with HiKey960 platform without these steps[1]. Similar issue is observed
> with Ferry's testing platform[2].
> 
> So, apply the required steps along with some fixes to Yu Chen's and John
> Stultz's version. The main fixes to their versions are the missing wait
> for clocks synchronization before clearing GCTL.CoreSoftReset and only
> apply DCTL.CSftRst when switching from host to device.
> 
> [1] https://urldefense.com/v3/__https://lore.kernel.org/linux-usb/20210108015115.27920-1-john.stultz@xxxxxxxxxx/__;!!A4F2R9G_pg!PW9Jbs4wv4a_zKGgZHN0FYrIpfecPX0Ouq9V3d16Yz-9-GSHqZWsfBAF-WkeqLhzN4i3$ 
> [2] https://urldefense.com/v3/__https://lore.kernel.org/linux-usb/0ba7a6ba-e6a7-9cd4-0695-64fc927e01f1@xxxxxxxxx/__;!!A4F2R9G_pg!PW9Jbs4wv4a_zKGgZHN0FYrIpfecPX0Ouq9V3d16Yz-9-GSHqZWsfBAF-WkeqGeZStt4$ 
> 
> Cc: Andy Shevchenko <andy.shevchenko@xxxxxxxxx>
> Cc: Ferry Toth <fntoth@xxxxxxxxx>
> Cc: Wesley Cheng <wcheng@xxxxxxxxxxxxxx>
> Cc: <stable@xxxxxxxxxxxxxxx>
> Fixes: 41ce1456e1db ("usb: dwc3: core: make dwc3_set_mode() work properly")
> Signed-off-by: Yu Chen <chenyu56@xxxxxxxxxx>
> Signed-off-by: John Stultz <john.stultz@xxxxxxxxxx>
> Signed-off-by: Thinh Nguyen <Thinh.Nguyen@xxxxxxxxxxxx>
> ---
> Changes in v3:
> - Check if the desired mode is OTG, then keep the old flow
> - Remove condition for OTG support only since the device can still be
>   configured DRD host/device mode only
> - Remove redundant hw_mode check since __dwc3_set_mode() only applies when
>   hw_mode is DRD
> Changes in v2:
> - Initialize mutex per device and not as global mutex.
> - Add additional checks for DRD only mode
> 
>  drivers/usb/dwc3/core.c | 27 +++++++++++++++++++++++++++
>  drivers/usb/dwc3/core.h |  5 +++++
>  2 files changed, 32 insertions(+)
> 

Hi John,

If possible, can you run a test with this version on your platform?

Thanks,
Thinh





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