linux-kernel - Re: [PATCH v1] usb: typec: tipd: keep default interrupts enabled during probe()

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Date:   Tue, 11 Jan 2022 11:11:55 +0200
From:   Heikki Krogerus <heikki.krogerus@...ux.intel.com>
To:     Martin Kepplinger <martin.kepplinger@...i.sm>
Cc:     gregkh@...uxfoundation.org, sven@...npeter.dev,
        hdegoede@...hat.com, marcan@...can.st, kernel@...i.sm,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1] usb: typec: tipd: keep default interrupts enabled
 during probe()

Hi Martin,

On Mon, Jan 10, 2022 at 05:35:59PM +0100, Martin Kepplinger wrote:
> Commit 9990f2f6264c ("usb: typec: tipd: Enable event interrupts by default")
> writes a fixed set of interrupts to TPS_REG_INT_MASK1. In case interrupts
> had been enabled by the firmware by default, these get disabled now
> which can break use cases. Only append to what is already enabled instead.

No, we have to know what are the interrupts that are actually needed.
Commmit 9990f2f6264c fixed an interrupt flood issue that was seen on
some platforms where the firmware I guess enabled absolutely
everything. This would just revert that.

So only enable the interrupts that you know you need.

> Fixes: 9990f2f6264c ("usb: typec: tipd: Enable event interrupts by default")

What is this fixing? What are the use cases you are talking about?

> Signed-off-by: Martin Kepplinger <martin.kepplinger@...i.sm>
> ---
>  drivers/usb/typec/tipd/core.c | 10 +++++++---
>  1 file changed, 7 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/usb/typec/tipd/core.c b/drivers/usb/typec/tipd/core.c
> index 6d27a5b5e3ca..365ee5494c15 100644
> --- a/drivers/usb/typec/tipd/core.c
> +++ b/drivers/usb/typec/tipd/core.c
> @@ -744,10 +744,14 @@ static int tps6598x_probe(struct i2c_client *client)
>  
>  		irq_handler = cd321x_interrupt;
>  	} else {
> +		ret = tps6598x_read64(tps, TPS_REG_INT_MASK1, &mask1);
> +		if (ret)
> +			return ret;
> +
>  		/* Enable power status, data status and plug event interrupts */
> -		mask1 = TPS_REG_INT_POWER_STATUS_UPDATE |
> -			TPS_REG_INT_DATA_STATUS_UPDATE |
> -			TPS_REG_INT_PLUG_EVENT;
> +		mask1 |= TPS_REG_INT_POWER_STATUS_UPDATE |
> +			 TPS_REG_INT_DATA_STATUS_UPDATE |
> +			 TPS_REG_INT_PLUG_EVENT;
>  	}
>  
>  	/* Make sure the controller has application firmware running */

thanks,

-- 
heikki