On Fri, May 06, 2016 at 04:34:08PM +0200, Noralf Trønnes wrote:
Den 06.05.2016 16:15, skrev Thierry Reding:
On Fri, May 06, 2016 at 04:08:16PM +0200, Daniel Vetter wrote:
On Fri, May 06, 2016 at 04:03:47PM +0200, Thierry Reding wrote:
On Thu, May 05, 2016 at 03:24:34PM +0200, Noralf Trønnes wrote:
Add function to create a simple connector for a panel.
I'm not sure I see the usefulness of this. Typically you'd attach a panel to an encoder/connector, in which case you already have the connector.
Perhaps it would become more obvious why we need this if you posted patches that show where this is used?
The other helpers give you a simple drm pipeline with plane, crtc & encoder all baked into on drm_simple_pipeline structure. The only thing variable you have to hook up to that is the drm_connector. And I think for dead-simple panels avoiding the basic boilerplate in that does indeed make some sense.
Avoiding boilerplate is good, but I have a difficult time envisioning how you might want to use this. At the same time I'm asking myself how we know that this helper is any good if we haven't seen it used anywhere and actually see the boilerplate go away.
I pulled out the patches from the tinydrm patchset that would go into drm core and helpers. I'm not very good at juggling many patches around in various version and getting it right. I'm doing development in the downstream Raspberry Pi repo on 4.5 to get all the pi drivers, and then apply it on linux-next...
This is the tinydrm patch that will use it: https://lists.freedesktop.org/archives/dri-devel/2016-April/104502.html
Extract: +int tinydrm_display_pipe_init(struct tinydrm_device *tdev,
const uint32_t *formats, unsigned int format_count)+{
- struct drm_device *dev = tdev->base;
- struct drm_connector *connector;
- int ret;
- connector = drm_simple_kms_panel_connector_create(dev, &tdev->panel,
DRM_MODE_CONNECTOR_VIRTUAL);- if (IS_ERR(connector))
return PTR_ERR(connector);- ret = drm_simple_display_pipe_init(dev, &tdev->pipe,
&tinydrm_display_pipe_funcs,formats, format_count,connector);- return ret;
+} +EXPORT_SYMBOL(tinydrm_display_pipe_init);
It's imo even more impressive when you show the entire driver, including all the hooks. Because there's just 4 of them iirc, all optional.
And besides the tinydrm panel drivers in it's various editions we could also use this for simpledrm (the boot-up firmware kms driver from David Herrmann) and probably a few other super-simple display drivers. Essentially with this I think drm is now better suited for dumb&simple hardware than fbdev. -Daniel