linux-kernel - Re: [PATCH v7 3/4] usb: dwc2: assert phy reset when waking up in rk3288 platform

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <ba3e8239-6909-9de1-9cc5-f7ae80825f58@synopsys.com>
Date:   Tue, 6 Sep 2016 11:54:16 -0700
From:   John Youn <John.Youn@...opsys.com>
To:     Kishon Vijay Abraham I <kishon@...com>,
        Randy Li <ayaka@...lik.info>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>
CC:     "felipe.balbi@...ux.intel.com" <felipe.balbi@...ux.intel.com>,
        "John.Youn@...opsys.com" <John.Youn@...opsys.com>,
        "mark.rutland@....com" <mark.rutland@....com>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "heiko@...ech.de" <heiko@...ech.de>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-rockchip@...ts.infradead.org" 
        <linux-rockchip@...ts.infradead.org>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "randy.li@...k-chips.com" <randy.li@...k-chips.com>
Subject: Re: [PATCH v7 3/4] usb: dwc2: assert phy reset when waking up in
 rk3288 platform

On 9/5/2016 10:15 PM, Kishon Vijay Abraham I wrote:
> Hi,
> 
> On Sunday 04 September 2016 03:25 AM, Randy Li wrote:
>> On the rk3288 USB host-only port (the one that's not the OTG-enabled
>> port) the PHY can get into a bad state when a wakeup is asserted (not
>> just a wakeup from full system suspend but also a wakeup from
>> autosuspend).
>>
>> We can get the PHY out of its bad state by asserting its "port reset",
>> but unfortunately that seems to assert a reset onto the USB bus so it
>> could confuse things if we don't actually deenumerate / reenumerate the
>> device.
>>
>> We can also get the PHY out of its bad state by fully resetting it using
>> the reset from the CRU (clock reset unit) in chip, which does a more full
>> reset.  The CRU-based reset appears to actually cause devices on the bus
>> to be removed and reinserted, which fixes the problem (albeit in a hacky
>> way).
>>
>> It's unfortunate that we need to do a full re-enumeration of devices at
>> wakeup time, but this is better than alternative of letting the bus get
>> wedged.
>>
>> Signed-off-by: Randy Li <ayaka@...lik.info>
>> ---
>>  drivers/usb/dwc2/core_intr.c | 12 ++++++++++++
>>  1 file changed, 12 insertions(+)
>>
>> diff --git a/drivers/usb/dwc2/core_intr.c b/drivers/usb/dwc2/core_intr.c
>> index d85c5c9..08485b7 100644
>> --- a/drivers/usb/dwc2/core_intr.c
>> +++ b/drivers/usb/dwc2/core_intr.c
>> @@ -345,6 +345,7 @@ static void dwc2_handle_session_req_intr(struct dwc2_hsotg *hsotg)
>>  static void dwc2_handle_wakeup_detected_intr(struct dwc2_hsotg *hsotg)
>>  {
>>  	int ret;
>> +	struct device_node *np = hsotg->dev->of_node;
>>  
>>  	/* Clear interrupt */
>>  	dwc2_writel(GINTSTS_WKUPINT, hsotg->regs + GINTSTS);
>> @@ -379,6 +380,17 @@ static void dwc2_handle_wakeup_detected_intr(struct dwc2_hsotg *hsotg)
>>  			/* Restart the Phy Clock */
>>  			pcgcctl &= ~PCGCTL_STOPPCLK;
>>  			dwc2_writel(pcgcctl, hsotg->regs + PCGCTL);
>> +
>> +			/*
>> +			 * It is a quirk in Rockchip RK3288, causing by
>> +			 * a hardware bug. This will propagate out and
>> +			 * eventually we'll re-enumerate the device. 
>> +			 * Not great but the best we can do 
>> +			 */
>> +			if (of_device_is_compatible(np, "rockchip,rk3288-usb")
>> +					&& (NULL != hsotg->phy->ops->reset))
>> +				hsotg->phy->ops->reset(hsotg->phy);
> 
> never call the phy ops directly from the controller driver. It has to be
> protected as well.

It looks like we should be calling an API function instead, correct?

Similar to the wrappers for the other ops.

Regards,
John