[RFC 0/1] drm: Add Grain Media GM12U320 kms driver

[Marco Diego Aurélio Mesquita]

On Wed, Jun 7, 2017 at 4:38 PM, Noralf Trønnes <noralf at tronnes.org> wrote:
>
> Den 07.06.2017 20.46, skrev Marco Diego Aurélio Mesquita:
>>
>> Hi Noralf!
>>
>> On Wed, Jun 7, 2017 at 1:56 PM, Noralf Trønnes <noralf at tronnes.org> wrote:
>>>
>>> tinydrm is targeted at displays on slow busses where userspace tells
>>> the driver which part of the framebuffer it has changed to minimize
>>> the transfer.
>>>
>>> The PL111 driver uses drm_simple_display_pipe and might be a better
>>> example for your use case:
>>> https://cgit.freedesktop.org/drm/drm-misc/tree/drivers/gpu/drm/pl111
>>
>> I'll investigate how to modify the pl111 driver to fit my needs then.
>> Do you think is there any change that must be done to the
>> pl111_get_panel function regarding the call to
>> of_graph_get_next_endpoint? I mean, the udl driver (which the gm12u320
>> driver is based on) does not have a panel; would any change be needed
>> because of this?
>
>
> I guess you can keep your get_modes and do something like this:
>
> static const struct drm_connector_helper_funcs gm12u320_helper_funcs = {
>     .get_modes = gm12u320_get_modes,
> };
>
> .best_encoder has a default that fits your 1 encoder case.
>
> static const struct drm_connector_funcs gm12u320_connector_funcs = {
>     .fill_modes = drm_helper_probe_single_connector_modes,
>     .destroy = gm12u320_connector_destroy,
>     .detect = gm12u320_detect,
>     .dpms = drm_atomic_helper_connector_dpms,
>     .reset = drm_atomic_helper_connector_reset,
>     .atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
>     .atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
> };
>
> Then you init and add helper:
>     drm_connector_init(dev, connector, &gm12u320_connector_funcs,
>                DRM_MODE_CONNECTOR_Unknown);
>     drm_connector_helper_add(connector, &gm12u320_helper_funcs);
>
> And finally attach the connector to the pipe:
>     drm_simple_display_pipe_init(..., connector);
>
> The connector is registered when the drm device is registered.
>

Thanks Noralf! That's exactly what I did and I'll test it soon. The
parts that scare me the most are the calls to
of_graph_get_next_endpoint, of_property_read_u32_array and of_node_put
(in display.c, for example). I'm still not sure those will work.