[Letux-kernel] [PATCH v8 4/8] drm/ingenic: Add dw-hdmi driver for jz4780

H. Nikolaus Schaller hns at goldelico.com
Wed Nov 24 22:28:43 CET 2021

Hi Paul,

>>> You probably should disable the regulator (if not NULL) here.
>> Indeed. Would it be ok to make struct regulator *regulator static
>> or do we need dynamically allocated memory?
> static non-const is almost always a bad idea, so avoid it.

Well some years ago it was a perfectly simple solution that still works...
But I asked because I had a lot of doubt.

> You can either:
> - create a "ingenic_dw_hdmi" struct that will contain a pointer to dw_hdmi and a pointer to the regulator. Instanciate it in the probe with devm_kzalloc() and set the pointers, then set it as the driver data (platform_set_drvdata). In the remove function you can then obtain the pointer to your ingenic_dw_hdmi struct with platform_get_drvdata(), and you can remove the dw_hdmi and unregister the regulator.
> - register cleanup functions, using devm_add_action_or_reset(dev, f, priv). When it's time to cleanup, the kernel core will call f(priv) automatically. So you can add a small wrapper around dw_hdmi_remove() and another one around regulator_disable(), and those will be called automatically if your probe function fails, or when the driver is removed. Then you can completely remove the ".remove" callback. There are a few examples of these in the ingenic-drm-drv.c if you want to take a look.

The second one turned out to be cleaner to handle special cases like if there is no regulator. We just register the disabler only if there is a regulator and enable succeeds.

So v9 is coming now.

BR and thanks,

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