Commit 2340dc15 authored Apr 08, 2020 by Thierry Reding

drm/tegra: Properly reference count the DDC I2C adapter



Use the of_get_i2c_adapter_by_node(), which is similar to the existing
call to of_find_i2c_adapter_by_node() except that it also takes a
reference to the owner module of the I2C adapter. In order to properly
balance this out, call i2c_put_adapter() to release the reference to the
I2C adapter and its owner module.

For the special case where the DDC comes from the DPAUX, care must be
taken to perform the same steps (i.e. get_device() and module_get()) so
that the reference counts are all balanced.

Signed-off-by: Thierry Reding <treding@nvidia.com>

parent 9123e3a7

drivers/gpu/drm/tegra/output.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -112,7 +112,7 @@ int tegra_output_probe(struct tegra_output *output)

		ddc = of_parse_phandle(output->of_node, "nvidia,ddc-i2c-bus", 0);
		if (ddc) {
		output->ddc = of_find_i2c_adapter_by_node(ddc);
		output->ddc = of_get_i2c_adapter_by_node(ddc);
		if (!output->ddc) {
		err = -EPROBE_DEFER;
		of_node_put(ddc);
		@@ -173,7 +173,7 @@ void tegra_output_remove(struct tegra_output *output)
		free_irq(output->hpd_irq, output);

		if (output->ddc)
		put_device(&output->ddc->dev);
		i2c_put_adapter(output->ddc);
		}

		int tegra_output_init(struct drm_device drm, struct tegra_output output)

drivers/gpu/drm/tegra/sor.c

+6 −1

Original line number	Diff line number	Diff line
		@@ -3728,7 +3728,12 @@ static int tegra_sor_probe(struct platform_device *pdev)
		if (!sor->aux)
		return -EPROBE_DEFER;

		if (get_device(&sor->aux->ddc.dev)) {
		if (try_module_get(sor->aux->ddc.owner))
		sor->output.ddc = &sor->aux->ddc;
		else
		put_device(&sor->aux->ddc.dev);
		}
		}

		if (!sor->aux) {