Re: [PATCH 2/5] drm: add helper to get crtc timings (v3)

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Tue, Nov 18, 2014 at 09:12:49AM -0800, Matt Roper wrote:
> From: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
> 
> We need to get hdisplay and vdisplay in a few places so create a
> helper to make our job easier.
> 
> v2 (by Matt): Use new stereo doubling function (suggested by Ville)
> 
> v3 (by Matt):
>  - Add missing kerneldoc (Daniel)
>  - Use drm_mode_copy() (Jani)
> 
> Cc: dri-devel@lists.freedesktop.org
> Suggested-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
> Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
> ---
>  drivers/gpu/drm/drm_crtc.c           | 32 ++++++++++++++++++++++----------
>  drivers/gpu/drm/i915/intel_display.c |  6 +++---
>  include/drm/drm_crtc.h               |  2 ++
>  3 files changed, 27 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
> index 56737e7..be1a485 100644
> --- a/drivers/gpu/drm/drm_crtc.c
> +++ b/drivers/gpu/drm/drm_crtc.c
> @@ -2494,6 +2494,27 @@ int drm_mode_set_config_internal(struct drm_mode_set *set)
>  EXPORT_SYMBOL(drm_mode_set_config_internal);
>  
>  /**
> + * drm_crtc_get_hv_timing - Fetches hdisplay/vdisplay for given mode
> + * @mode: mode to query
> + * @hdisplay: hdisplay value to fill in
> + * @vdisplay: vdisplay value to fill in
> + *
> + * The vdisplay value will be doubled if the specified mode is a stereo mode of
> + * the appropriate layout.
> + */
> +void drm_crtc_get_hv_timing(const struct drm_display_mode *mode,
> +			    int *hdisplay, int *vdisplay)
> +{
> +	struct drm_display_mode adjusted;
> +
> +	drm_mode_copy(&adjusted, mode);
> +	drm_mode_stereo_double(&adjusted);

Hmm. The mode may not have the crtc_ timings populated at all here, so
drm_mode_stereo_double() might just double some zeroes/garbage.

I don't recall anymore if I had some clever idea how to do this. I was
hoping we can avoid duplicating the stereo doubling logic in more than
once place, but maybe it's just easier to admit defeat?

I guess the options are:
1) duplciate some stereo doubling logic
2) populate the required crtc_ timings here as well
3) keep using drm_mode_set_crtcinfo() but remove the offending stuff
   from the copied mode so that it doesn't interfere with the results
4) add more flags to drm_mode_set_crtcinfo() that prevent the offending
   stuff from affecting the results

> +	*hdisplay = adjusted.crtc_hdisplay;
> +	*vdisplay = adjusted.crtc_vdisplay;
> +}
> +EXPORT_SYMBOL(drm_crtc_get_hv_timing);
> +
> +/**
>   * drm_crtc_check_viewport - Checks that a framebuffer is big enough for the
>   *     CRTC viewport
>   * @crtc: CRTC that framebuffer will be displayed on
> @@ -2510,16 +2531,7 @@ int drm_crtc_check_viewport(const struct drm_crtc *crtc,
>  {
>  	int hdisplay, vdisplay;
>  
> -	hdisplay = mode->hdisplay;
> -	vdisplay = mode->vdisplay;
> -
> -	if (drm_mode_is_stereo(mode)) {
> -		struct drm_display_mode adjusted = *mode;
> -
> -		drm_mode_set_crtcinfo(&adjusted, CRTC_STEREO_DOUBLE);
> -		hdisplay = adjusted.crtc_hdisplay;
> -		vdisplay = adjusted.crtc_vdisplay;
> -	}
> +	drm_crtc_get_hv_timing(mode, &hdisplay, &vdisplay);
>  
>  	if (crtc->invert_dimensions)
>  		swap(hdisplay, vdisplay);
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 320bf4c..a967623 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -10158,9 +10158,9 @@ intel_modeset_pipe_config(struct drm_crtc *crtc,
>  	 * computation to clearly distinguish it from the adjusted mode, which
>  	 * can be changed by the connectors in the below retry loop.
>  	 */
> -	drm_mode_set_crtcinfo(&pipe_config->requested_mode, CRTC_STEREO_DOUBLE);
> -	pipe_config->pipe_src_w = pipe_config->requested_mode.crtc_hdisplay;
> -	pipe_config->pipe_src_h = pipe_config->requested_mode.crtc_vdisplay;
> +	drm_crtc_get_hv_timing(&pipe_config->requested_mode,
> +			       &pipe_config->pipe_src_w,
> +			       &pipe_config->pipe_src_h);
>  
>  encoder_retry:
>  	/* Ensure the port clock defaults are reset when retrying. */
> diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
> index 7b28ab0..23236f6 100644
> --- a/include/drm/drm_crtc.h
> +++ b/include/drm/drm_crtc.h
> @@ -1138,6 +1138,8 @@ extern int drm_plane_init(struct drm_device *dev,
>  extern void drm_plane_cleanup(struct drm_plane *plane);
>  extern unsigned int drm_plane_index(struct drm_plane *plane);
>  extern void drm_plane_force_disable(struct drm_plane *plane);
> +extern void drm_crtc_get_hv_timing(const struct drm_display_mode *mode,
> +				   int *hdisplay, int *vdisplay);
>  extern int drm_crtc_check_viewport(const struct drm_crtc *crtc,
>  				   int x, int y,
>  				   const struct drm_display_mode *mode,
> -- 
> 1.8.5.1
> 
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-- 
Ville Syrjälä
Intel OTC
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