[PATCH v4 2/2] drm/panel: Add device_link from panel device to drm device

[Peter Rosin]

On 2018-05-23 11:39, Andrzej Hajda wrote:

*snip*

> Panels are managed by dsi host only if dsi host implements it, and it is
> up to dsi host author, it is not mandatory. The only case I am aware of
> is exynos-dsi. I guess most developers are not aware of the problem, or
> they do not care, or ... whatever. This patch shows it very clearly.

*snip*

> With such approach you do not protect dsi hosts without dynamic panel
> management support. As I said earlier: it is matter of panel consumers
> (for example dsi host), ie if it implements dynamic panel management, it
> should attach panel without creating device_links, as it take care of
> disappearing panels. If it does not perform dynamic management it should
> rely on default behavior - links should be created, to protect drm
> device from using dangling pointers.

So, you're saying that the only place that needs to be patched to call
drm_panel_attach_without_link is exynos_dsi_host_attach()?

What about the dw-mipi-dsi driver in rockchip/dw-mipi-dsi.c? It also
calls drm_panel_attach/drm_panel_detach in its dw_mipi_dsi_host_attach
and dw_mipi_dsi_host_detach functions.

Similar thing in bridge/synopsis/dw-mipi-dsi.c, but it calls the
wrappers drm_panel_bridge_add/remove to create an implicit bridge
that in turn handles the panel. So, do we need a to add a
drm_panel_bridge_add_without_link too?

What about tegra/dsi.c? It also calls drm_panel_attach in its
tegra_dsi_host_attach function? But that one doesn't detach the
panel in its tegra_dsi_host_detach. Is that a bug?

Cheers,
Peter