linux-kernel - Re: [PATCH v9 0/7] platform/chrome: Introduce DT hardware prober

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Message-ID: <ZxDgQISmr_gn_aDF@smile.fi.intel.com>
Date: Thu, 17 Oct 2024 13:00:32 +0300
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: Chen-Yu Tsai <wenst@...omium.org>
Cc: Rob Herring <robh@...nel.org>, Saravana Kannan <saravanak@...gle.com>,
	Matthias Brugger <matthias.bgg@...il.com>,
	AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>,
	Wolfram Sang <wsa@...nel.org>, Benson Leung <bleung@...omium.org>,
	Tzung-Bi Shih <tzungbi@...nel.org>, chrome-platform@...ts.linux.dev,
	devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org,
	Douglas Anderson <dianders@...omium.org>,
	Johan Hovold <johan@...nel.org>, Jiri Kosina <jikos@...nel.org>,
	linux-i2c@...r.kernel.org
Subject: Re: [PATCH v9 0/7] platform/chrome: Introduce DT hardware prober

On Thu, Oct 17, 2024 at 05:34:35PM +0800, Chen-Yu Tsai wrote:

> For the I2C component (touchscreens and trackpads) case from the
> original series, the hardware prober driver finds the particular
> class of device in the device tree, gets its parent I2C adapter,
> and tries to initiate a simple I2C read for each device under that
> I2C bus. When it finds one that responds, it considers that one
> present, marks it as "okay", and returns, letting the driver core
> actually probe the device.
> 
> This works fine in most cases since these components are connected
> via a ribbon cable and always have the same resources. The prober
> will also grab these resources and enable them.
> 
> The other case, selecting a display panel to use based on the SKU ID
> from the firmware, hit a bit of an issue with fixing the OF graph.
> It has been left out since v3.
> 
> Patch 1 adds of_changeset_update_prop_string(), as requested by Rob.
> 
> Patch 2 adds for_each_child_of_node_with_prefix(), as suggested by Andy.

> Patch 3 implements probing the I2C bus for presence of components as
> a hookable helper function in the I2C core.
> 
> Patch 4 implements regulator supply support as a set of simple helpers
> for the I2C component prober.
> 
> Patch 5 implements GPIO support for the I2C component prober simple
> helpers.

Not that I am really a fan of the idea, but I have nothing to counter propose.
Also my big concern about random msleep() calls seems to be addressed in a way
that it's now a caller's problem to supply the (correct) one.

Hence FWIW,
Reviewed-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
for patches 3,4, and 5.

> Patch 6 adds a ChromeOS specific DT hardware prober. This initial
> version targets the Hana Chromebooks, probing its I2C trackpads and
> touchscreens.
> 
> Patch 7 modifies the Hana device tree and marks the touchscreens
> and trackpads as "fail-needs-probe", ready for the driver to probe.

-- 
With Best Regards,
Andy Shevchenko