[PATCH] drm: Don't override active mode.

[Forest Bond]

Hi,

Please disregard this patch, I'll resend with tweaks.

Thanks,
Forest

On Sun, Jun 13, 2010 at 12:39:56PM -0400, Forest Bond wrote:
> The drm renderer calls drmModeSetCrtc to tell the CRTC to use the
> allocated scan out buffer.  This should not result in setting a
> new mode for the CRTC, but can do exactly that since plymouth saves
> the wrong mode when creating heads, and inadvertently overrides the
> initial mode set by the kernel.
> 
> The root of the problem is the assumption that the first mode in the
> connector's mode list is the current active mode.  This will be true
> if the active mode is set by automatic detection, as the kernel will
> have selected the first mode in the list as the initial mode, but it
> will not be true if the user has selected a different mode via the
> video= kernel boot parameter.
> 
> To fix this, the saved mode is copied from the controller itself,
> unless that mode is for some reason not valid, in which case we fall
> back to the old behavior (which could result in a mode switch).
> 
> Signed-off-by: Forest Bond <forest at alittletooquiet.net>
> ---
>  src/plugins/renderers/drm/plugin.c |   35 ++++++++++++++++++++++++++++++++---
>  1 files changed, 32 insertions(+), 3 deletions(-)
> 
> diff --git a/src/plugins/renderers/drm/plugin.c b/src/plugins/renderers/drm/plugin.c
> index 385bd91..7976e21 100644
> --- a/src/plugins/renderers/drm/plugin.c
> +++ b/src/plugins/renderers/drm/plugin.c
> @@ -159,6 +159,7 @@ ply_renderer_head_free (ply_renderer_head_t *head)
>    ply_trace ("freeing %ldx%ld renderer head", head->area.width, head->area.height);
>    ply_pixel_buffer_free (head->pixel_buffer);
>    drmModeFreeConnector (head->connector);
> +  drmModeFreeModeInfo (head->mode);
>    free (head);
>  }
>  
> @@ -547,12 +548,21 @@ close_device (ply_renderer_backend_t *backend)
>  }
>  
>  static drmModeModeInfo *
> -get_active_mode_for_connector (ply_renderer_backend_t *backend,
> -                               drmModeConnector       *connector)
> +get_preferred_mode_for_connector (ply_renderer_backend_t *backend,
> +                                  drmModeConnector       *connector)
>  {
>    return &connector->modes[0];
>  }
>  
> +static drmModeModeInfo *
> +get_active_mode_for_controller (ply_renderer_backend_t  *backend,
> +                                drmModeCrtc             *controller)
> +{
> +  if (controller->mode_valid)
> +    return &controller->mode;
> +  return NULL;
> +}
> +
>  static bool
>  controller_is_available (ply_renderer_backend_t *backend,
>                           uint32_t                controller_id)
> @@ -725,6 +735,8 @@ create_heads_for_active_connectors (ply_renderer_backend_t *backend)
>        uint32_t encoder_id;
>        uint32_t console_buffer_id;
>        drmModeModeInfo *mode;
> +      drmModeModeInfo *src_mode;
> +      drmModeCrtc *controller;
>  
>        connector = drmModeGetConnector (backend->device_fd,
>                                         backend->resources->connectors[i]);
> @@ -762,7 +774,24 @@ create_heads_for_active_connectors (ply_renderer_backend_t *backend)
>            continue;
>          }
>  
> -      mode = get_active_mode_for_connector (backend, connector);
> +      mode = malloc (sizeof (drmModeModeInfo));
> +      controller = drmModeGetCrtc (backend->device_fd, controller_id);
> +      /* Try to preserve the active mode for the controller. */
> +      src_mode = get_active_mode_for_controller (backend, controller);
> +      if (src_mode)
> +        {
> +          /* Active mode is set and valid, use it. */
> +          memcpy (mode, src_mode, sizeof (drmModeModeInfo));
> +        }
> +      else
> +        {
> +          /* Fall back to setting the preferred mode for the connector.
> +           * This will result in changing the active mode if one is set.
> +           */
> +          src_mode = get_preferred_mode_for_connector (backend, connector);
> +          memcpy (mode, src_mode, sizeof (drmModeModeInfo));
> +        }
> +      drmModeFreeCrtc (controller);
>  
>        console_buffer_id = get_console_buffer_id (backend, controller_id);
>  
> -- 
> 1.7.0.4
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