linux-kernel - Re: [PATCH 3/8] usb: dwc3: core: Skip setting event buffers for host only controllers

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Date:   Mon, 13 Mar 2023 08:26:45 +0530
From:   Krishna Kurapati PSSNV <quic_kriskura@...cinc.com>
To:     Dongliang Mu <mudongliangabcd@...il.com>
CC:     Thinh Nguyen <Thinh.Nguyen@...opsys.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        "Andy Gross" <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        "Konrad Dybcio" <konrad.dybcio@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Felipe Balbi <balbi@...nel.org>, <linux-usb@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <linux-arm-msm@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <quic_pkondeti@...cinc.com>,
        <quic_ppratap@...cinc.com>, <quic_wcheng@...cinc.com>,
        <quic_jackp@...cinc.com>, <quic_harshq@...cinc.com>,
        <ahalaney@...hat.com>, <quic_shazhuss@...cinc.com>
Subject: Re: [PATCH 3/8] usb: dwc3: core: Skip setting event buffers for host
 only controllers



On 3/13/2023 7:37 AM, Dongliang Mu wrote:
> On Sat, Mar 11, 2023 at 12:40 AM Krishna Kurapati
> <quic_kriskura@...cinc.com> wrote:
>>
>> On some SoC's like SA8295P where the teritiary controller is host-only
>> capable, GEVTADDRHI/LO, GEVTSIZ, GEVTCOUNT registers are not accessible.
>> Trying to setup them up during core_init leads to a crash.
>>
>> For DRD/Peripheral supported controllers, event buffer setup is done
>> again in gadget_pullup. Skip setup or cleanup of event buffers if
>> controller is host-only capable.
>>
>> Signed-off-by: Krishna Kurapati <quic_kriskura@...cinc.com>
>> ---
>>   drivers/usb/dwc3/core.c | 20 ++++++++++++++------
>>   1 file changed, 14 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
>> index 076c0f8a4441..1ca9fa40a66e 100644
>> --- a/drivers/usb/dwc3/core.c
>> +++ b/drivers/usb/dwc3/core.c
>> @@ -840,7 +840,11 @@ static void dwc3_clk_disable(struct dwc3 *dwc)
>>
>>   static void dwc3_core_exit(struct dwc3 *dwc)
>>   {
>> -       dwc3_event_buffers_cleanup(dwc);
>> +       unsigned int    hw_mode;
>> +
>> +       hw_mode = DWC3_GHWPARAMS0_MODE(dwc->hwparams.hwparams0);
>> +       if (hw_mode != DWC3_GHWPARAMS0_MODE_HOST)
>> +               dwc3_event_buffers_cleanup(dwc);
> 
> quick question about dwc3_event_buffers_cleanup, there are other
> similar sites calling this function.
> 
> C symbol: dwc3_event_buffers_cleanup
> 
>    File   Function                   Line
> 0 core.h <global>                   1546 void
> dwc3_event_buffers_cleanup(struct dwc3 *dwc);
> 1 core.c __dwc3_set_mode             152 dwc3_event_buffers_cleanup(dwc);
> 2 core.c dwc3_event_buffers_cleanup  522 void
> dwc3_event_buffers_cleanup(struct dwc3 *dwc)
> 3 core.c dwc3_core_exit              842 dwc3_event_buffers_cleanup(dwc);
> 4 core.c dwc3_probe                 1936 dwc3_event_buffers_cleanup(dwc);
> 5 drd.c  dwc3_otg_update             363 dwc3_event_buffers_cleanup(dwc);
> 6 drd.c  dwc3_drd_exit               607 dwc3_event_buffers_cleanup(dwc);
> 
> For 1, 5, and 6, any need to take care of this situation?
> 
Hi Dongliang,

   Thanks for the review.
In the other places mentioned like set_mode otg_update or drd_exit, 
cleanup is called if we are in device mode and we want to exit that 
mode. Since for MP, we have a host only controller those paths won't be 
accessed I believe.

Regards,
Krishna,
>>
>>          usb_phy_set_suspend(dwc->usb2_phy, 1);
>>          usb_phy_set_suspend(dwc->usb3_phy, 1);
>> @@ -1177,10 +1181,12 @@ static int dwc3_core_init(struct dwc3 *dwc)
>>          if (ret < 0)
>>                  goto err3;
>>
>> -       ret = dwc3_event_buffers_setup(dwc);
>> -       if (ret) {
>> -               dev_err(dwc->dev, "failed to setup event buffers\n");
>> -               goto err4;
>> +       if (hw_mode != DWC3_GHWPARAMS0_MODE_HOST) {
>> +               ret = dwc3_event_buffers_setup(dwc);
>> +               if (ret) {
>> +                       dev_err(dwc->dev, "failed to setup event buffers\n");
>> +                       goto err4;
>> +               }
>>          }
>>
>>          /*
>> @@ -2008,7 +2014,9 @@ static int dwc3_probe(struct platform_device *pdev)
>>
>>   err5:
>>          dwc3_debugfs_exit(dwc);
>> -       dwc3_event_buffers_cleanup(dwc);
>> +
>> +       if (hw_mode != DWC3_GHWPARAMS0_MODE_HOST)
>> +               dwc3_event_buffers_cleanup(dwc);
>>
>>          usb_phy_set_suspend(dwc->usb2_phy, 1);
>>          usb_phy_set_suspend(dwc->usb3_phy, 1);
>> --
>> 2.39.0
>>