Re: [PATCH 8/9] drm/i915: add ->display.modeset_global_resources callback

[Paulo Zanoni <przanoni@gmail.com>]

Hi

2012/10/26 Daniel Vetter <daniel.vetter@ffwll.ch>:
> After all relevant pipes are disabled and after we've updated all the
> state with the staged state, but before we call the per-crtc
> ->mode_set functions there's a very natural point to set up any
> shared/global resources like
> - shared plls (obviously only the setup, the enabling needs to be
>   separately handling with a separate refcount)
> - global watermark state like the DSPARB on gmch platforms
> - workaround bits that depend upon the exact global output
>   configuration
> - enabling the right set of refclocks
> - enabling/disabling manual power wells.
>
> Now for a lot of these things we can't move them into this function
> yet, most often because we only compute the required information in
> the per-crtc ->mode_set callback. Which is too late. But due to a
> bunch of reasons (check-only atomic modeset, fastboot&hw state checks,
> ...) we need to separate the computation of that state from the actual
> hw frobbery anyway. So we can move things into this new callback step-
> by-step.
>
> Others can't be moved here (or implemented at all) because our code
> lacks the smarts to properly update them. E.g. the DSPARB can only be
> updated when all pipes are disabled, so if we decide to change it's
> value, we need to disable _all_ pipes. The infrastructure for that is
> already in place (with the various pipe masks that driver the modeset
> logic). But again we need to move a few things out of ->mode_set
> first before we can even implement the correct decision making.
>
> In any case, we need to start somewhere, so let's start with the
> callback: Some small follow-up patches will make immediate good use of
> it.
>
> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

Yes, I can see cases where this is needed and even thought about doing
something similar for a specific task. In the future we might want a
global function that runs on all gens before calling the gen-specific
functions, but for now let's keep it this way.

Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com>

> ---
>  drivers/gpu/drm/i915/i915_drv.h      | 1 +
>  drivers/gpu/drm/i915/intel_display.c | 3 +++
>  2 files changed, 4 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index b0ca786..6531d3e 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -249,6 +249,7 @@ struct drm_i915_display_funcs {
>                                  uint32_t sprite_width, int pixel_size);
>         void (*update_linetime_wm)(struct drm_device *dev, int pipe,
>                                  struct drm_display_mode *mode);
> +       void (*modeset_global_resources)(struct drm_device *dev);
>         int (*crtc_mode_set)(struct drm_crtc *crtc,
>                              struct drm_display_mode *mode,
>                              struct drm_display_mode *adjusted_mode,
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 7a9cfc2..7009c0f 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -7403,6 +7403,9 @@ bool intel_set_mode(struct drm_crtc *crtc,
>          * update the the output configuration. */
>         intel_modeset_update_state(dev, prepare_pipes);
>
> +       if (dev_priv->display.modeset_global_resources)
> +               dev_priv->display.modeset_global_resources(dev);
> +
>         /* Set up the DPLL and any encoders state that needs to adjust or depend
>          * on the DPLL.
>          */
> --
> 1.7.11.4
>
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-- 
Paulo Zanoni