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Message-ID: <20241008205658.no3kfap7wmlshci2@synopsys.com>
Date: Tue, 8 Oct 2024 20:57:00 +0000
From: Thinh Nguyen <Thinh.Nguyen@...opsys.com>
To: Roger Quadros <rogerq@...nel.org>
CC: Thinh Nguyen <Thinh.Nguyen@...opsys.com>,
"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 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.
>
> >
> >> + }
> >> +
> >> 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")
BR,
Thinh
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