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Message-ID: <5e6bb315-7896-4e63-86aa-1a219b7a7fb3@kernel.org>
Date: Mon, 7 Oct 2024 14:44:35 +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
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.
>
>> + }
>> +
>> 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.
>
> Thanks for the patch!
>
> BR,
> Thinh
--
cheers,
-roger
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