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Message-ID: <20240806232836.52rkn7u3g5uiotn3@synopsys.com>
Date: Tue, 6 Aug 2024 23:28:41 +0000
From: Thinh Nguyen <Thinh.Nguyen@...opsys.com>
To: Kyle Tso <kyletso@...gle.com>
CC: Thinh Nguyen <Thinh.Nguyen@...opsys.com>,
"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
"raychi@...gle.com" <raychi@...gle.com>,
"badhri@...gle.com" <badhri@...gle.com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
"royluo@...gle.com" <royluo@...gle.com>,
"bvanassche@....org" <bvanassche@....org>,
"stable@...r.kernel.org" <stable@...r.kernel.org>
Subject: Re: [PATCH v3] usb: dwc3: Runtime get and put usb power_supply handle
On Sun, Aug 04, 2024, Kyle Tso wrote:
> It is possible that the usb power_supply is registered after the probe
Should we defer the dwc3 probe until the power_supply is registered
then?
> of dwc3. In this case, trying to get the usb power_supply during the
> probe will fail and there is no chance to try again. Also the usb
> power_supply might be unregistered at anytime so that the handle of it
This is problematic... If the power_supply is unregistered, the device
is no longer usable.
> in dwc3 would become invalid. To fix this, get the handle right before
> calling to power_supply functions and put it afterward.
Shouldn't the life-cycle of the dwc3 match with the power_supply? How
can we maintain function without the proper power_supply?
BR,
Thinh
>
> dwc3_gadet_vbus_draw might be in interrupt context. Create a kthread
> worker beforehand and use it to process the "might-sleep"
> power_supply_put ASAP after the property set.
>
> Fixes: 6f0764b5adea ("usb: dwc3: add a power supply for current control")
> Cc: stable@...r.kernel.org
> Signed-off-by: Kyle Tso <kyletso@...gle.com>
> ---
> v2 -> v3:
> - Only move power_supply_put to a work. Still call _get_by_name and
> _set_property in dwc3_gadget_vbus_draw.
> - Create a kthread_worker to handle the work
>
> v1 -> v2:
> - move power_supply_put out of interrupt context
>
> drivers/usb/dwc3/core.c | 29 ++++++++++++----------------
> drivers/usb/dwc3/core.h | 6 ++++--
> drivers/usb/dwc3/gadget.c | 40 +++++++++++++++++++++++++++++++++++----
> 3 files changed, 52 insertions(+), 23 deletions(-)
>
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index 734de2a8bd21..82c8376330d7 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -1631,8 +1631,6 @@ static void dwc3_get_properties(struct dwc3 *dwc)
> u8 tx_thr_num_pkt_prd = 0;
> u8 tx_max_burst_prd = 0;
> u8 tx_fifo_resize_max_num;
> - const char *usb_psy_name;
> - int ret;
>
> /* default to highest possible threshold */
> lpm_nyet_threshold = 0xf;
> @@ -1667,12 +1665,7 @@ static void dwc3_get_properties(struct dwc3 *dwc)
>
> dwc->sys_wakeup = device_may_wakeup(dwc->sysdev);
>
> - ret = device_property_read_string(dev, "usb-psy-name", &usb_psy_name);
> - if (ret >= 0) {
> - dwc->usb_psy = power_supply_get_by_name(usb_psy_name);
> - if (!dwc->usb_psy)
> - dev_err(dev, "couldn't get usb power supply\n");
> - }
> + device_property_read_string(dev, "usb-psy-name", &dwc->usb_psy_name);
>
> dwc->has_lpm_erratum = device_property_read_bool(dev,
> "snps,has-lpm-erratum");
> @@ -2132,19 +2125,24 @@ static int dwc3_probe(struct platform_device *pdev)
>
> dwc3_get_software_properties(dwc);
>
> + dwc->worker = kthread_create_worker(0, "dwc3-worker");
> + if (IS_ERR(dwc->worker))
> + return PTR_ERR(dwc->worker);
> + sched_set_fifo(dwc->worker->task);
> +
> dwc->reset = devm_reset_control_array_get_optional_shared(dev);
> if (IS_ERR(dwc->reset)) {
> ret = PTR_ERR(dwc->reset);
> - goto err_put_psy;
> + goto err_destroy_worker;
> }
>
> ret = dwc3_get_clocks(dwc);
> if (ret)
> - goto err_put_psy;
> + goto err_destroy_worker;
>
> ret = reset_control_deassert(dwc->reset);
> if (ret)
> - goto err_put_psy;
> + goto err_destroy_worker;
>
> ret = dwc3_clk_enable(dwc);
> if (ret)
> @@ -2245,9 +2243,8 @@ static int dwc3_probe(struct platform_device *pdev)
> dwc3_clk_disable(dwc);
> err_assert_reset:
> reset_control_assert(dwc->reset);
> -err_put_psy:
> - if (dwc->usb_psy)
> - power_supply_put(dwc->usb_psy);
> +err_destroy_worker:
> + kthread_destroy_worker(dwc->worker);
>
> return ret;
> }
> @@ -2258,6 +2255,7 @@ static void dwc3_remove(struct platform_device *pdev)
>
> pm_runtime_get_sync(&pdev->dev);
>
> + kthread_destroy_worker(dwc->worker);
> dwc3_core_exit_mode(dwc);
> dwc3_debugfs_exit(dwc);
>
> @@ -2276,9 +2274,6 @@ static void dwc3_remove(struct platform_device *pdev)
> pm_runtime_set_suspended(&pdev->dev);
>
> dwc3_free_event_buffers(dwc);
> -
> - if (dwc->usb_psy)
> - power_supply_put(dwc->usb_psy);
> }
>
> #ifdef CONFIG_PM
> diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
> index 1e561fd8b86e..3fc58204db6e 100644
> --- a/drivers/usb/dwc3/core.h
> +++ b/drivers/usb/dwc3/core.h
> @@ -993,6 +993,7 @@ struct dwc3_scratchpad_array {
> /**
> * struct dwc3 - representation of our controller
> * @drd_work: workqueue used for role swapping
> + * @worker: dedicated kthread worker
> * @ep0_trb: trb which is used for the ctrl_req
> * @bounce: address of bounce buffer
> * @setup_buf: used while precessing STD USB requests
> @@ -1045,7 +1046,7 @@ struct dwc3_scratchpad_array {
> * @role_sw: usb_role_switch handle
> * @role_switch_default_mode: default operation mode of controller while
> * usb role is USB_ROLE_NONE.
> - * @usb_psy: pointer to power supply interface.
> + * @usb_psy_name: name of the usb power supply interface
> * @usb2_phy: pointer to USB2 PHY
> * @usb3_phy: pointer to USB3 PHY
> * @usb2_generic_phy: pointer to array of USB2 PHYs
> @@ -1163,6 +1164,7 @@ struct dwc3_scratchpad_array {
> */
> struct dwc3 {
> struct work_struct drd_work;
> + struct kthread_worker *worker;
> struct dwc3_trb *ep0_trb;
> void *bounce;
> u8 *setup_buf;
> @@ -1223,7 +1225,7 @@ struct dwc3 {
> struct usb_role_switch *role_sw;
> enum usb_dr_mode role_switch_default_mode;
>
> - struct power_supply *usb_psy;
> + const char *usb_psy_name;
>
> u32 fladj;
> u32 ref_clk_per;
> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> index 89fc690fdf34..1ff583281eff 100644
> --- a/drivers/usb/dwc3/gadget.c
> +++ b/drivers/usb/dwc3/gadget.c
> @@ -30,6 +30,11 @@
> #define DWC3_ALIGN_FRAME(d, n) (((d)->frame_number + ((d)->interval * (n))) \
> & ~((d)->interval - 1))
>
> +struct dwc3_psy_put {
> + struct kthread_work work;
> + struct power_supply *psy;
> +};
> +
> /**
> * dwc3_gadget_set_test_mode - enables usb2 test modes
> * @dwc: pointer to our context structure
> @@ -3047,22 +3052,49 @@ static void dwc3_gadget_set_ssp_rate(struct usb_gadget *g,
> spin_unlock_irqrestore(&dwc->lock, flags);
> }
>
> +static void dwc3_gadget_psy_put(struct kthread_work *work)
> +{
> + struct dwc3_psy_put *psy_put = container_of(work, struct dwc3_psy_put, work);
> +
> + power_supply_put(psy_put->psy);
> + kfree(psy_put);
> +}
> +
> static int dwc3_gadget_vbus_draw(struct usb_gadget *g, unsigned int mA)
> {
> - struct dwc3 *dwc = gadget_to_dwc(g);
> + struct dwc3 *dwc = gadget_to_dwc(g);
> + struct power_supply *usb_psy;
> union power_supply_propval val = {0};
> + struct dwc3_psy_put *psy_put;
> int ret;
>
> if (dwc->usb2_phy)
> return usb_phy_set_power(dwc->usb2_phy, mA);
>
> - if (!dwc->usb_psy)
> + if (!dwc->usb_psy_name)
> return -EOPNOTSUPP;
>
> + usb_psy = power_supply_get_by_name(dwc->usb_psy_name);
> + if (!usb_psy) {
> + dev_err(dwc->dev, "couldn't get usb power supply\n");
> + return -ENODEV;
> + }
> +
> val.intval = 1000 * mA;
> - ret = power_supply_set_property(dwc->usb_psy, POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT, &val);
> + ret = power_supply_set_property(usb_psy, POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT, &val);
> + if (ret < 0) {
> + dev_err(dwc->dev, "failed to set power supply property\n");
> + return ret;
> + }
>
> - return ret;
> + psy_put = kzalloc(sizeof(*psy_put), GFP_ATOMIC);
> + if (!psy_put)
> + return -ENOMEM;
> + kthread_init_work(&psy_put->work, dwc3_gadget_psy_put);
> + psy_put->psy = usb_psy;
> + kthread_queue_work(dwc->worker, &psy_put->work);
> +
> + return 0;
> }
>
> /**
> --
> 2.46.0.rc2.264.g509ed76dc8-goog
>
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