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Date: Wed, 13 Apr 2022 14:42:41 +0300
From: Roger Quadros <rogerq@...nel.org>
To: Aswath Govindraju <a-govindraju@...com>,
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
On 13/04/2022 13:51, Aswath Govindraju wrote:
> 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 don't see why not. It must be clear from the binding documentation that
interrupt property is required unless polling mode is specified.
>
>
>>>
>>> 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
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