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Message-ID: <914fda0d-036f-4c69-a1e7-94e403b196e1@kernel.org>
Date: Wed, 9 Oct 2024 14:49:58 +0300
From: Roger Quadros <rogerq@...nel.org>
To: Thinh Nguyen <Thinh.Nguyen@...opsys.com>
Cc: "Rafael J. Wysocki" <rafael@...nel.org>, Len Brown <len.brown@...el.com>,
Pavel Machek <pavel@....cz>, Greg Kroah-Hartman
<gregkh@...uxfoundation.org>, Nishanth Menon <nm@...com>,
Tero Kristo <kristo@...nel.org>, Santosh Shilimkar <ssantosh@...nel.org>,
Dhruva Gole <d-gole@...com>, Vishal Mahaveer <vishalm@...com>,
"msp@...libre.com" <msp@...libre.com>, "srk@...com" <srk@...com>,
"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>,
"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
"stable@...r.kernel.org" <stable@...r.kernel.org>
Subject: Re: [PATCH] usb: dwc3: core: Fix system suspend on TI AM62 platforms
On 08/10/2024 23:57, Thinh Nguyen wrote:
> Hi,
>
> On Mon, Oct 07, 2024, Roger Quadros wrote:
>> Hi,
>>
>> On 05/10/2024 04:04, Thinh Nguyen wrote:
>>> Hi,
>>>
>>> On Tue, Oct 01, 2024, Roger Quadros wrote:
>>>> Since commit 6d735722063a ("usb: dwc3: core: Prevent phy suspend during init"),
>>>> system suspend is broken on AM62 TI platforms.
>>>>
>>>> Before that commit, both DWC3_GUSB3PIPECTL_SUSPHY and DWC3_GUSB2PHYCFG_SUSPHY
>>>> bits (hence forth called 2 SUSPHY bits) were being set during core
>>>> initialization and even during core re-initialization after a system
>>>> suspend/resume.
>>>>
>>>> These bits are required to be set for system suspend/resume to work correctly
>>>> on AM62 platforms.
>>>>
>>>> Since that commit, the 2 SUSPHY bits are not set for DEVICE/OTG mode if gadget
>>>> driver is not loaded and started.
>>>> For Host mode, the 2 SUSPHY bits are set before the first system suspend but
>>>> get cleared at system resume during core re-init and are never set again.
>>>>
>>>> This patch resovles these two issues by ensuring the 2 SUSPHY bits are set
>>>> before system suspend and restored to the original state during system resume.
>>>>
>>>> Cc: stable@...r.kernel.org # v6.9+
>>>> Fixes: 6d735722063a ("usb: dwc3: core: Prevent phy suspend during init")
>>>> Link: https://urldefense.com/v3/__https://lore.kernel.org/all/1519dbe7-73b6-4afc-bfe3-23f4f75d772f@kernel.org/__;!!A4F2R9G_pg!ahChm4MaKd6VGYqbnM4X1_pY_jqavYDv5HvPFbmicKuhvFsBwlEFi1xO5itGuHmfjbRuUSzReJISf5-1gXpr$
>>>> Signed-off-by: Roger Quadros <rogerq@...nel.org>
>>>> ---
>>>> drivers/usb/dwc3/core.c | 16 ++++++++++++++++
>>>> drivers/usb/dwc3/core.h | 2 ++
>>>> 2 files changed, 18 insertions(+)
>>>>
>>>> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
>>>> index 9eb085f359ce..1233922d4d54 100644
>>>> --- a/drivers/usb/dwc3/core.c
>>>> +++ b/drivers/usb/dwc3/core.c
>>>> @@ -2336,6 +2336,9 @@ static int dwc3_suspend_common(struct dwc3 *dwc, pm_message_t msg)
>>>> u32 reg;
>>>> int i;
>>>>
>>>> + dwc->susphy_state = !!(dwc3_readl(dwc->regs, DWC3_GUSB2PHYCFG(0)) &
>>>> + DWC3_GUSB2PHYCFG_SUSPHY);
>>>> +
>>>> switch (dwc->current_dr_role) {
>>>> case DWC3_GCTL_PRTCAP_DEVICE:
>>>> if (pm_runtime_suspended(dwc->dev))
>>>> @@ -2387,6 +2390,11 @@ static int dwc3_suspend_common(struct dwc3 *dwc, pm_message_t msg)
>>>> break;
>>>> }
>>>>
>>>> + if (!PMSG_IS_AUTO(msg)) {
>>>> + if (!dwc->susphy_state)
>>>> + dwc3_enable_susphy(dwc, true);
>>>> + }
>>>> +
>>>> return 0;
>>>> }
>>>>
>>>> @@ -2454,6 +2462,14 @@ static int dwc3_resume_common(struct dwc3 *dwc, pm_message_t msg)
>>>> break;
>>>> }
>>>>
>>>> + if (!PMSG_IS_AUTO(msg)) {
>>>> + /* dwc3_core_init_for_resume() disables SUSPHY so just handle
>>>> + * the enable case
>>>> + */
>>>
>>> Can we note that this is a particular behavior needed for AM62 here?
>>> And can we use this comment style:
>>>
>>> /*
>>> * xxxxx
>>> * xxxxx
>>> */
>>
>> OK.
>>
>>>
>>>
>>>> + if (dwc->susphy_state)
>>>
>>> Shouldn't we check for if (!dwc->susphy_state) and clear the susphy
>>> bits?
>>
>> In that case it would have already been cleared so no need to check
>> and clear again.
>>
>>>
>>>> + dwc3_enable_susphy(dwc, true);
>>>
>>> The dwc3_enable_susphy() set and clear both GUSB3PIPECTL_SUSPHY and
>>> GUSB2PHYCFG_SUSPHY, perhaps we should split that function out so we can
>>> only need to set for GUSB2PHYCFG_SUSPHY since you only track for that.
>>
>> As dwc3_enable_susphy() sets and clears both GUSB3PIPECTL_SUSPHY and
>> GUSB2PHYCFG_SUSPHY together it doesn't really help to track both
>> separately, but just complicates things.
>
> Then we should check if either GUSB2PHYCFG_SUSPHY or GUSB3PIPECTL_SUSPHY
> is set, then apply this.
Yes. I will do this.
>
>>
>>>
>>>> + }
>>>> +
>>>> return 0;
>>>> }
>>>>
>>>> diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
>>>> index c71240e8f7c7..b2ed5aba4c72 100644
>>>> --- a/drivers/usb/dwc3/core.h
>>>> +++ b/drivers/usb/dwc3/core.h
>>>> @@ -1150,6 +1150,7 @@ struct dwc3_scratchpad_array {
>>>> * @sys_wakeup: set if the device may do system wakeup.
>>>> * @wakeup_configured: set if the device is configured for remote wakeup.
>>>> * @suspended: set to track suspend event due to U3/L2.
>>>> + * @susphy_state: state of DWC3_GUSB2PHYCFG_SUSPHY before PM suspend.
>>>> * @imod_interval: set the interrupt moderation interval in 250ns
>>>> * increments or 0 to disable.
>>>> * @max_cfg_eps: current max number of IN eps used across all USB configs.
>>>> @@ -1382,6 +1383,7 @@ struct dwc3 {
>>>> unsigned sys_wakeup:1;
>>>> unsigned wakeup_configured:1;
>>>> unsigned suspended:1;
>>>> + unsigned susphy_state:1;
>>>>
>>>> u16 imod_interval;
>>>>
>>>>
>>>> ---
>>>> base-commit: 9852d85ec9d492ebef56dc5f229416c925758edc
>>>> change-id: 20240923-am62-lpm-usb-f420917bd707
>>>>
>>>> Best regards,
>>>> --
>>>> Roger Quadros <rogerq@...nel.org>
>>>>
>>>
>>> <rant/>
>>> While reviewing your change, I see that we misuse the
>>> dis_u2_susphy_quirk to make this property a conditional thing during
>>> suspend and resume for certain platform. That bugs me because we can't
>>> easily change it without the reported hardware to test.
>>> </rant>
>>
>> No it is not conditional. if dis_u2_susphy_quirk or dis_u3_susphy_quirk
>> is set then we never enable the respective U2/U3 SUSPHY bit.
>>
>
> I'm not referring to your change. I was referring to this in particular:
> bcb128777af5 ("usb: dwc3: core: Suspend PHYs on runtime suspend in host mode")
I get it now.
--
cheers,
-roger
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