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Date: Tue, 24 Oct 2023 11:41:51 -0700
From: Elson Serrao <quic_eserrao@...cinc.com>
To: Roger Quadros <rogerq@...nel.org>, <gregkh@...uxfoundation.org>,
<Thinh.Nguyen@...opsys.com>, <robh+dt@...nel.org>,
<krzysztof.kozlowski+dt@...aro.org>, <conor+dt@...nel.org>,
<devicetree@...r.kernel.org>
CC: <linux-kernel@...r.kernel.org>, <linux-usb@...r.kernel.org>
Subject: Re: [PATCH v4 3/3] usb: dwc3: Modify runtime pm ops to handle bus
suspend
On 10/24/2023 3:14 AM, Roger Quadros wrote:
> Hi Elson,
>
> On 14/08/2023 21:50, Elson Roy Serrao wrote:
>> The current implementation blocks the runtime pm operations when cable
>> is connected. This would block dwc3 to enter a low power state during
>> bus suspend scenario. Modify the runtime pm ops to handle bus suspend
>> case for such platforms where the controller low power mode entry/exit
>> is handled by the glue driver. This enablement is controlled through a
>> dt property and platforms capable of detecting bus resume can benefit
>> from this feature. Also modify the remote wakeup operations to trigger
>> runtime resume before sending wakeup signal.
>>
>> Signed-off-by: Elson Roy Serrao <quic_eserrao@...cinc.com>
>> ---
>> drivers/usb/dwc3/core.c | 28 ++++++++++++++++++++++++++--
>> drivers/usb/dwc3/core.h | 3 +++
>> drivers/usb/dwc3/gadget.c | 32 +++++++++++++++++++++++++-------
>> 3 files changed, 54 insertions(+), 9 deletions(-)
>>
>> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
>> index 9c6bf054f15d..9bfd9bb18caf 100644
>> --- a/drivers/usb/dwc3/core.c
>> +++ b/drivers/usb/dwc3/core.c
>> @@ -1518,6 +1518,9 @@ static void dwc3_get_properties(struct dwc3 *dwc)
>> dwc->dis_split_quirk = device_property_read_bool(dev,
>> "snps,dis-split-quirk");
>>
>> + dwc->runtime_suspend_on_usb_suspend = device_property_read_bool(dev,
>> + "snps,runtime-suspend-on-usb-suspend");
>> +
>> dwc->lpm_nyet_threshold = lpm_nyet_threshold;
>> dwc->tx_de_emphasis = tx_de_emphasis;
>>
>> @@ -2029,6 +2032,9 @@ static int dwc3_resume_common(struct dwc3 *dwc, pm_message_t msg)
>>
>> switch (dwc->current_dr_role) {
>> case DWC3_GCTL_PRTCAP_DEVICE:
>> + /* runtime resume on bus resume scenario */
>> + if (PMSG_IS_AUTO(msg) && dwc->connected)
>> + break;
>> ret = dwc3_core_init_for_resume(dwc);
>> if (ret)
>> return ret;
>> @@ -2090,8 +2096,13 @@ static int dwc3_runtime_checks(struct dwc3 *dwc)
>> {
>> switch (dwc->current_dr_role) {
>> case DWC3_GCTL_PRTCAP_DEVICE:
>> - if (dwc->connected)
>> + if (dwc->connected) {
>> + /* bus suspend scenario */
>> + if (dwc->runtime_suspend_on_usb_suspend &&
>> + dwc->suspended)
>
> If dwc is already suspended why do we return -EBUSY?
> Should this be !dwc->suspended?
>
Hi Roger
Thank you for reviewing.
If dwc->suspended is true (i.e suspend event due to U3/L2 is received),
I am actually breaking from this switch statement and returning 0.
>> + break;
>> return -EBUSY;
>> + }
>> break;
>> case DWC3_GCTL_PRTCAP_HOST:
>> default:
>> @@ -2107,9 +2118,22 @@ static int dwc3_runtime_suspend(struct device *dev)
>> struct dwc3 *dwc = dev_get_drvdata(dev);
>> int ret;
>>
>> - if (dwc3_runtime_checks(dwc))
>> + ret = dwc3_runtime_checks(dwc);
>> + if (ret)
>> return -EBUSY;
>>
>> + switch (dwc->current_dr_role) {
>> + case DWC3_GCTL_PRTCAP_DEVICE:
>> + /* bus suspend case */
>> + if (!ret && dwc->connected)
>
> No need to check !ret again as it will never happen because
> we are returning -EBUSY earlier if (ret);
>
Thanks for this catch. I will remove !ret check in v5.
>> + return 0;
>> + break;
>> + case DWC3_GCTL_PRTCAP_HOST:
>> + default:
>> + /* do nothing */
>> + break;
>> + }
>> +
>
> While this takes care of runtime suspend case, what about system_suspend?
> Should this check be moved to dwc3_suspend_common() instead?
>
Sure I can move these checks to dwc3_suspend_common to make it generic.
Will rename this patch to "Modify pm ops to handle bus suspend" since
this is now not limited to only runtime suspend/resume. Will also rename
dwc->runtime_suspend_on_usb_suspend to dwc->delegate_wakeup_interrupt
based on earlier feedback.
I am still working on a clean way to enable/disable this feature (i.e
set dwc->delegate_wakeup_interrupt flag) from the glue driver based on
Thinh's feedback .
I will accommodate above feedback as well and upload v5.
Thanks
Elson
>> ret = dwc3_suspend_common(dwc, PMSG_AUTO_SUSPEND);
>> if (ret)
>> return ret;
>> diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
>> index a69ac67d89fe..f2f788a6b4b5 100644
>> --- a/drivers/usb/dwc3/core.h
>> +++ b/drivers/usb/dwc3/core.h
>> @@ -1124,6 +1124,8 @@ struct dwc3_scratchpad_array {
>> * @num_ep_resized: carries the current number endpoints which have had its tx
>> * fifo resized.
>> * @debug_root: root debugfs directory for this device to put its files in.
>> + * @runtime_suspend_on_usb_suspend: true if dwc3 runtime suspend is allowed
>> + * during bus suspend scenario.
>> */
>> struct dwc3 {
>> struct work_struct drd_work;
>> @@ -1340,6 +1342,7 @@ struct dwc3 {
>> int last_fifo_depth;
>> int num_ep_resized;
>> struct dentry *debug_root;
>> + bool runtime_suspend_on_usb_suspend;
>> };
>>
>> #define INCRX_BURST_MODE 0
>> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
>> index 5fd067151fbf..978ce0e91164 100644
>> --- a/drivers/usb/dwc3/gadget.c
>> +++ b/drivers/usb/dwc3/gadget.c
>> @@ -2401,15 +2401,21 @@ static int dwc3_gadget_wakeup(struct usb_gadget *g)
>> return -EINVAL;
>> }
>>
>> - spin_lock_irqsave(&dwc->lock, flags);
>> if (!dwc->gadget->wakeup_armed) {
>> dev_err(dwc->dev, "not armed for remote wakeup\n");
>> - spin_unlock_irqrestore(&dwc->lock, flags);
>> return -EINVAL;
>> }
>> - ret = __dwc3_gadget_wakeup(dwc, true);
>>
>> + ret = pm_runtime_resume_and_get(dwc->dev);
>> + if (ret < 0) {
>> + pm_runtime_set_suspended(dwc->dev);
>> + return ret;
>> + }
>> +
>> + spin_lock_irqsave(&dwc->lock, flags);
>> + ret = __dwc3_gadget_wakeup(dwc, true);
>> spin_unlock_irqrestore(&dwc->lock, flags);
>> + pm_runtime_put_noidle(dwc->dev);
>>
>> return ret;
>> }
>> @@ -2428,6 +2434,12 @@ static int dwc3_gadget_func_wakeup(struct usb_gadget *g, int intf_id)
>> return -EINVAL;
>> }
>>
>> + ret = pm_runtime_resume_and_get(dwc->dev);
>> + if (ret < 0) {
>> + pm_runtime_set_suspended(dwc->dev);
>> + return ret;
>> + }
>> +
>> spin_lock_irqsave(&dwc->lock, flags);
>> /*
>> * If the link is in U3, signal for remote wakeup and wait for the
>> @@ -2438,6 +2450,7 @@ static int dwc3_gadget_func_wakeup(struct usb_gadget *g, int intf_id)
>> ret = __dwc3_gadget_wakeup(dwc, false);
>> if (ret) {
>> spin_unlock_irqrestore(&dwc->lock, flags);
>> + pm_runtime_put_noidle(dwc->dev);
>> return -EINVAL;
>> }
>> dwc3_resume_gadget(dwc);
>> @@ -2452,6 +2465,7 @@ static int dwc3_gadget_func_wakeup(struct usb_gadget *g, int intf_id)
>> dev_err(dwc->dev, "function remote wakeup failed, ret:%d\n", ret);
>>
>> spin_unlock_irqrestore(&dwc->lock, flags);
>> + pm_runtime_put_noidle(dwc->dev);
>>
>> return ret;
>> }
>> @@ -2732,21 +2746,23 @@ static int dwc3_gadget_pullup(struct usb_gadget *g, int is_on)
>> /*
>> * Avoid issuing a runtime resume if the device is already in the
>> * suspended state during gadget disconnect. DWC3 gadget was already
>> - * halted/stopped during runtime suspend.
>> + * halted/stopped during runtime suspend except for bus suspend case
>> + * where we would have skipped the controller halt.
>> */
>> if (!is_on) {
>> pm_runtime_barrier(dwc->dev);
>> - if (pm_runtime_suspended(dwc->dev))
>> + if (pm_runtime_suspended(dwc->dev) && !dwc->connected)
>> return 0;
>> }
>>
>> /*
>> * Check the return value for successful resume, or error. For a
>> * successful resume, the DWC3 runtime PM resume routine will handle
>> - * the run stop sequence, so avoid duplicate operations here.
>> + * the run stop sequence except for bus resume case, so avoid
>> + * duplicate operations here.
>> */
>> ret = pm_runtime_get_sync(dwc->dev);
>> - if (!ret || ret < 0) {
>> + if ((!ret && !dwc->connected) || ret < 0) {
>> pm_runtime_put(dwc->dev);
>> if (ret < 0)
>> pm_runtime_set_suspended(dwc->dev);
>> @@ -4331,6 +4347,8 @@ static void dwc3_gadget_suspend_interrupt(struct dwc3 *dwc,
>> }
>>
>> dwc->link_state = next;
>> + pm_runtime_mark_last_busy(dwc->dev);
>> + pm_request_autosuspend(dwc->dev);
>> }
>>
>> static void dwc3_gadget_interrupt(struct dwc3 *dwc,
>
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