On Wed, Oct 01, 2014 at 11:28:46AM +0200, Jean-Francois Moine wrote:
On Tue, 30 Sep 2014 20:25:40 +0100 Mark Brown broonie@kernel.org wrote:
- request_module("snd-soc-hdmi-codec");
- pdev = platform_device_register_resndata(&priv->hdmi->dev,
"hdmi-audio-codec",PLATFORM_DEVID_NONE,NULL, 0,&tda998x_hdmi_data,sizeof tda998x_hdmi_data);Why is this request_module() needed? If there is a good reason for it we should have some documentation.
The reason is simple: as the HDMI CODEC is not declared in the DT, the associated module must be loaded in memory.
Module auto-loading works in non-DT environments too. Unlike the direction that the arm port is going, the core kernel features, such as driver autoloading, are coded *not* to require DT (or indeed any particular firmware.)
There are circumstances where this has been lost sight of (such as the gpiod stuff), but as a general rule, features do not rely on DT.
Platform drivers will be auto-loaded if they have:
MODULE_ALIAS(PLATFORM_MODULE_PREFIX DRIVER_NAME);
and DRIVER_NAME matches the non-id part of the platform device name. In the case of platform driver ID tables:
MODULE_DEVICE_TABLE(platform, id-table);