linux-kernel - Re: [PATCH v5 1/2] dt-bindings: i2c: pca954x: Add timeout reset property

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Message-ID:
 <DB6PR07MB35091425FE5CBCD782B465A69D412@DB6PR07MB3509.eurprd07.prod.outlook.com>
Date: Sat, 19 Oct 2024 11:09:43 +0000
From: "Wojciech Siudy (Nokia)" <wojciech.siudy@...ia.com>
To: Rob Herring <robh@...nel.org>
CC: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-i2c@...r.kernel.org" <linux-i2c@...r.kernel.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"andi.shyti@...nel.org" <andi.shyti@...nel.org>, "peda@...ntia.se"
	<peda@...ntia.se>
Subject: Re: [PATCH v5 1/2] dt-bindings: i2c: pca954x: Add timeout reset
 property

Hi!

> If you have a reset GPIO for the mux, then why wouldn't just use it
> on timeout?

Because we cannot do that on every board. The reset GPIO is provided to
ensure, that we have reset signal de-asserted during initialisation.
You might have connected other devices to the same reset line so this
must be a configurable option.

> What happens if you timeout and don't have this property? Just 
give up?

This would be the case just like before introducting this change. Some
aplications might do other attempt, the bus driver can try recovery.
Unfortunately common reset line for multiple chips is not a rare
situation.

> Does the timeout time need to be configurable?

The timeout we are talking about is error code returned from function
pca954x_reg_write(), which calls smbus xfer that is out of this driver
scope so there is nothing we can configure.

Regards,
Wojciech