Use drm_dp_aux_register_ddc/chardev() helpers that allow to register I2C adapter separately from the character device. This fixes broken display panel driver of Acer Chromebook CB5-311 that fails to probe starting with v5.13 kernel when DP AUX registration order was changed. Tegra SOR driver is never probed now using the new registration order because tegra-output always fails with -EPROBE_DEFER due to missing display panel that requires DP AUX DDC to be registered first. The offending commit made DDC to be registered after SOR's output, which can't ever happen. Use new helpers to restore the registration order and revive display panel.
Cc: stable@vger.kernel.org # 5.13+ Fixes: 39c17ae60ea9 ("drm/tegra: Don't register DP AUX channels before connectors") Reported-by: Thomas Graichen thomas.graichen@gmail.com # T124 Nyan Big Tested-by: Thomas Graichen thomas.graichen@gmail.com # T124 Nyan Big Signed-off-by: Dmitry Osipenko digetx@gmail.com --- drivers/gpu/drm/tegra/dpaux.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/tegra/dpaux.c b/drivers/gpu/drm/tegra/dpaux.c index 1f96e416fa08..e0d675c7c2e5 100644 --- a/drivers/gpu/drm/tegra/dpaux.c +++ b/drivers/gpu/drm/tegra/dpaux.c @@ -532,7 +532,9 @@ static int tegra_dpaux_probe(struct platform_device *pdev) dpaux->aux.transfer = tegra_dpaux_transfer; dpaux->aux.dev = &pdev->dev;
- drm_dp_aux_init(&dpaux->aux); + err = drm_dp_aux_register_ddc(&dpaux->aux); + if (err < 0) + return err;
/* * Assume that by default the DPAUX/I2C pads will be used for HDMI, @@ -585,6 +587,8 @@ static int tegra_dpaux_remove(struct platform_device *pdev) pm_runtime_put_sync(&pdev->dev); pm_runtime_disable(&pdev->dev);
+ drm_dp_aux_unregister_ddc(&dpaux->aux); + mutex_lock(&dpaux_lock); list_del(&dpaux->list); mutex_unlock(&dpaux_lock); @@ -718,7 +722,7 @@ int drm_dp_aux_attach(struct drm_dp_aux *aux, struct tegra_output *output) int err;
aux->drm_dev = output->connector.dev; - err = drm_dp_aux_register(aux); + err = drm_dp_aux_register_chardev(aux); if (err < 0) return err;
@@ -759,7 +763,7 @@ int drm_dp_aux_detach(struct drm_dp_aux *aux) unsigned long timeout; int err;
- drm_dp_aux_unregister(aux); + drm_dp_aux_unregister_chardev(aux); disable_irq(dpaux->irq);
if (dpaux->output->panel) {