Re: [PATCH 2/4] Input: touchscreen - Extend touchscreen_parse_properties() to allow overriding settings with a module option

[Dmitry Torokhov <dmitry.torokhov@gmail.com>]

Hi Hans,

On Tue, Oct 25, 2022 at 02:29:28PM +0200, Hans de Goede wrote:
> On x86/ACPI platforms touchscreens mostly just work without needing any
> device/model specific configuration. But in some cases (mostly with Silead
> and Goodix touchscreens) it is still necessary to manually specify various
> touchscreen-properties on a per model basis.
> 
> This is handled by drivers/platform/x86/touchscreen_dmi.c which contains
> a large list of per-model touchscreen properties which it attaches to the
> (i2c)device before the touchscreen driver's probe() method gets called.
> This means that ATM changing these settings requires recompiling the
> kernel. This makes figuring out what settings/properties a specific
> touchscreen needs very hard for normal users to do.
> 
> Add a new, optional, settings_override string argument to
> touchscreen_parse_properties(), which takes a list of ; separated
> property-name=value pairs, e.g. :
> "touchscreen-size-x=1665;touchscreen-size-y=1140;touchscreen-swapped-x-y".
> 
> This new argument can be used by drivers to implement a module option which
> allows users to easily specify alternative settings for testing.
> 
> The 2 new touchscreen_property_read_u32() and
> touchscreen_property_read_bool() helpers are also exported so that
> drivers can use these to add settings-override support to the code
> for driver-specific properties.

I totally understand the motivation for this, but I do not think that
having special handling for only touchscreen properties is the right
thing to do. I would very much prefer is we had a more generic approach
of adding/overriding properties (via an swnode?).

Thanks.

-- 
Dmitry