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Date: Wed, 13 Apr 2022 16:21:13 +0530
From: Aswath Govindraju <a-govindraju@...com>
To: Roger Quadros <rogerq@...nel.org>,
Heikki Krogerus <heikki.krogerus@...ux.intel.com>
CC: Vignesh Raghavendra <vigneshr@...com>,
Kishon Vijay Abraham I <kishon@...com>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Sven Peter <sven@...npeter.dev>,
Alyssa Rosenzweig <alyssa@...enzweig.io>,
Hector Martin <marcan@...can.st>,
Saranya Gopal <saranya.gopal@...el.com>,
Jens Axboe <axboe@...nel.dk>, <linux-usb@...r.kernel.org>,
<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH RFC] usb: typec: tipd: Add support for polling interrupts
status when interrupt line is not connected
Hi Roger,
On 13/04/22 16:08, Roger Quadros wrote:
> Hi Aswath,
>
> On 13/04/2022 13:02, Aswath Govindraju wrote:
>> Hi Heikki,
>>
>> On 13/04/22 15:04, Heikki Krogerus wrote:
>>> Hi Aswath,
>>>
>>> On Tue, Apr 12, 2022 at 08:20:58PM +0530, Aswath Govindraju wrote:
>>>> In some cases the interrupt line from the pd controller may not be
>>>> connected. In these cases, poll the status of various events.
>>>
>>> Well, if the alert/interrupt line is not connected anywhere, then
>>> polling is the only way to go. I'm fine with that, but the driver
>>> really should be told that there is no interrupt. Using polling
>>> whenever request_threaded_irq() returns -EINVAL is wrong. We really
>>> should not even attempt to request the interrupt if there is no
>>> interrupt for the device.
>>>
>>> Isn't there any way you can get that information from DT? Or how is
>>> the device enumerated in your case?
>>>
>>
>> Would checking if (client->irq) field is populated, to decide between
>> polling and interrupts be a good approach?
>
> 'interrupt' and 'interrupt-names' are required properties in DT binding doc
> Documentation/devicetree/bindings/usb/ti,tps6598x.yaml
>
> You will need to add a new property to indicate that polling mode must be used
> and then interrupt properties become optional.
>
Doesn't adding polling support mean that we are making interrupts
optional? So, can't we directly make the properties optional in the
bindings?
>>
>> I am sorry but I did not understand what you meant by device getting
>> enumerated. The device is on an I2C bus and gets enumerated based on the
>> I2C address provided. The device does not have I2C_IRQ line connected,
>> in my case.
>
> I think he meant whether you are using device tree or something else.
>
ohh okay, Thank you.
Regards,
Aswath
>>
>> Thanks,
>> Aswath
>>
>>>> Suggested-by: Roger Quadros <rogerq@...nel.org>
>>>> Signed-off-by: Aswath Govindraju <a-govindraju@...com>
>>>> ---
>>>> drivers/usb/typec/tipd/core.c | 90 ++++++++++++++++++++++++++++++++---
>>>> 1 file changed, 83 insertions(+), 7 deletions(-)
>>>>
>>>> diff --git a/drivers/usb/typec/tipd/core.c b/drivers/usb/typec/tipd/core.c
>>>> index 16b4560216ba..fa52d2067d6d 100644
>>>> --- a/drivers/usb/typec/tipd/core.c
>>>> +++ b/drivers/usb/typec/tipd/core.c
>>>> @@ -15,6 +15,8 @@
>>>> #include <linux/interrupt.h>
>>>> #include <linux/usb/typec.h>
>>>> #include <linux/usb/role.h>
>>>> +#include <linux/workqueue.h>
>>>> +#include <linux/devm-helpers.h>
>>>>
>>>> #include "tps6598x.h"
>>>> #include "trace.h"
>>>> @@ -93,6 +95,8 @@ struct tps6598x {
>>>> struct power_supply *psy;
>>>> struct power_supply_desc psy_desc;
>>>> enum power_supply_usb_type usb_type;
>>>> +
>>>> + struct delayed_work wq_poll;
>>>> };
>>>>
>>>> static enum power_supply_property tps6598x_psy_props[] = {
>>>> @@ -473,9 +477,8 @@ static void tps6598x_handle_plug_event(struct tps6598x *tps, u32 status)
>>>> }
>>>> }
>>>>
>>>> -static irqreturn_t cd321x_interrupt(int irq, void *data)
>>>> +static int cd321x_handle_interrupt_status(struct tps6598x *tps)
>>>> {
>>>> - struct tps6598x *tps = data;
>>>> u64 event;
>>>> u32 status;
>>>> int ret;
>>>> @@ -513,14 +516,45 @@ static irqreturn_t cd321x_interrupt(int irq, void *data)
>>>> err_unlock:
>>>> mutex_unlock(&tps->lock);
>>>>
>>>> + if (ret)
>>>> + return ret;
>>>> +
>>>> if (event)
>>>> - return IRQ_HANDLED;
>>>> - return IRQ_NONE;
>>>> + return 0;
>>>> + return 1;
>>>> }
>>>>
>>>> -static irqreturn_t tps6598x_interrupt(int irq, void *data)
>>>> +static irqreturn_t cd321x_interrupt(int irq, void *data)
>>>> {
>>>> struct tps6598x *tps = data;
>>>> + int ret;
>>>> +
>>>> + ret = cd321x_handle_interrupt_status(tps);
>>>> + if (ret)
>>>> + return IRQ_NONE;
>>>> + return IRQ_HANDLED;
>>>> +}
>>>> +
>>>> +/* Time interval for Polling */
>>>> +#define POLL_INTERVAL 500 /* msecs */
>>>> +static void cd321x_poll_work(struct work_struct *work)
>>>> +{
>>>> + struct tps6598x *tps = container_of(to_delayed_work(work),
>>>> + struct tps6598x, wq_poll);
>>>> + int ret;
>>>> +
>>>> + ret = cd321x_handle_interrupt_status(tps);
>>>> + /*
>>>> + * If there is an error while reading the interrupt registers
>>>> + * then stop polling else, schedule another poll work item
>>>> + */
>>>> + if (!(ret < 0))
>>>> + queue_delayed_work(system_power_efficient_wq,
>>>> + &tps->wq_poll, msecs_to_jiffies(POLL_INTERVAL));
>>>> +}
>>>> +
>>>> +static int tps6598x_handle_interrupt_status(struct tps6598x *tps)
>>>> +{
>>>> u64 event1;
>>>> u64 event2;
>>>> u32 status;
>>>> @@ -561,9 +595,39 @@ static irqreturn_t tps6598x_interrupt(int irq, void *data)
>>>> err_unlock:
>>>> mutex_unlock(&tps->lock);
>>>>
>>>> + if (ret)
>>>> + return ret;
>>>> +
>>>> if (event1 | event2)
>>>> - return IRQ_HANDLED;
>>>> - return IRQ_NONE;
>>>> + return 0;
>>>> + return 1;
>>>> +}
>>>> +
>>>> +static irqreturn_t tps6598x_interrupt(int irq, void *data)
>>>> +{
>>>> + struct tps6598x *tps = data;
>>>> + int ret;
>>>> +
>>>> + ret = tps6598x_handle_interrupt_status(tps);
>>>> + if (ret)
>>>> + return IRQ_NONE;
>>>> + return IRQ_HANDLED;
>>>> +}
>>>> +
>>>> +static void tps6598x_poll_work(struct work_struct *work)
>>>> +{
>>>> + struct tps6598x *tps = container_of(to_delayed_work(work),
>>>> + struct tps6598x, wq_poll);
>>>> + int ret;
>>>> +
>>>> + ret = tps6598x_handle_interrupt_status(tps);
>>>> + /*
>>>> + * If there is an error while reading the interrupt registers
>>>> + * then stop polling else, schedule another poll work item
>>>> + */
>>>> + if (!(ret < 0))
>>>> + queue_delayed_work(system_power_efficient_wq,
>>>> + &tps->wq_poll, msecs_to_jiffies(POLL_INTERVAL));
>>>> }
>>>>
>>>> static int tps6598x_check_mode(struct tps6598x *tps)
>>>> @@ -704,6 +768,7 @@ static int devm_tps6598_psy_register(struct tps6598x *tps)
>>>> static int tps6598x_probe(struct i2c_client *client)
>>>> {
>>>> irq_handler_t irq_handler = tps6598x_interrupt;
>>>> + work_func_t work_poll_handler = tps6598x_poll_work;
>>>> struct device_node *np = client->dev.of_node;
>>>> struct typec_capability typec_cap = { };
>>>> struct tps6598x *tps;
>>>> @@ -748,6 +813,7 @@ static int tps6598x_probe(struct i2c_client *client)
>>>> APPLE_CD_REG_INT_PLUG_EVENT;
>>>>
>>>> irq_handler = cd321x_interrupt;
>>>> + work_poll_handler = cd321x_poll_work;
>>>> } else {
>>>> /* Enable power status, data status and plug event interrupts */
>>>> mask1 = TPS_REG_INT_POWER_STATUS_UPDATE |
>>>> @@ -846,6 +912,16 @@ static int tps6598x_probe(struct i2c_client *client)
>>>> irq_handler,
>>>> IRQF_SHARED | IRQF_ONESHOT,
>>>> dev_name(&client->dev), tps);
>>>> + if (ret == -EINVAL) {
>>>> + dev_warn(&client->dev, "Unable to find the interrupt, switching to polling\n");
>>>> + ret = devm_delayed_work_autocancel(tps->dev, &tps->wq_poll, work_poll_handler);
>>>> + if (ret)
>>>> + dev_err(&client->dev, "error while initializing workqueue\n");
>>>> + else
>>>> + queue_delayed_work(system_power_efficient_wq, &tps->wq_poll,
>>>> + msecs_to_jiffies(POLL_INTERVAL));
>>>> + }
>>>> +
>>>> if (ret) {
>>>> tps6598x_disconnect(tps, 0);
>>>> typec_unregister_port(tps->port);
>>>
>>> thanks,
>>>
>>
>>
>
> --
> cheers,
> -roger
--
Thanks,
Aswath
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