Re: [RFC 1/3] imx258: Defer probing on ident register read fail (on ACPI)

From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To: Sakari Ailus <sakari.ailus@linux.intel.com>
Cc: linux-acpi@vger.kernel.org, linux-media@vger.kernel.org,
	rafael@kernel.org
Subject: Re: [RFC 1/3] imx258: Defer probing on ident register read fail (on ACPI)
Date: Fri, 20 Aug 2021 15:20:55 +0300	[thread overview]
Message-ID: <YR+eJytxRcVpSxgA@smile.fi.intel.com> (raw)
In-Reply-To: <20210819201936.7390-2-sakari.ailus@linux.intel.com>

On Thu, Aug 19, 2021 at 11:19:34PM +0300, Sakari Ailus wrote:
> Return -EPROBE_DEFER if probing the device fails because of the I²C
> transaction (-EIO only). This generally happens when the power on sequence
> of the device has not been fully performed yet due to later probing of
> other drivers.

...

> +	if (ret == -EIO && is_acpi_device_node(dev_fwnode(&client->dev))) {

has_acpi_companion() is better to have here, no?

> +		/*
> +		 * If we get -EIO here and it's an ACPI device, there's a fair
> +		 * likelihood it's because the drivers required to power this
> +		 * device on have not probed yet. Thus return -EPROBE_DEFER.
> +		 */
> +		return -EPROBE_DEFER;
> +	}

-- 
With Best Regards,
Andy Shevchenko