[PATCH 5/6] compositor-drm: Fix refresh rate selection in drm_output_switch_mode

[Derek Foreman]

On 02/04/15 12:10 AM, Mario Kleiner wrote:
> The matching logic in choose_mode() compared refresh rate
> of a drm_mode candidate mode expressed in Hz against the
> requested refresh rate of the target weston_mode expressed
> in milliHz, so the match always failed and the logic always
> ended up the mode with the highest refresh rate for a given
> resolution, instead of the one matching the requested rate.
> 
> Match proper fields to fix this.
> 
> Signed-off-by: Mario Kleiner <mario.kleiner.de at gmail.com>
> ---
>  src/compositor-drm.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/src/compositor-drm.c b/src/compositor-drm.c
> index 9ddb6d6..396938f 100644
> --- a/src/compositor-drm.c
> +++ b/src/compositor-drm.c
> @@ -1270,7 +1270,7 @@ choose_mode (struct drm_output *output, struct weston_mode *target_mode)
>  	wl_list_for_each(mode, &output->base.mode_list, base.link) {
>  		if (mode->mode_info.hdisplay == target_mode->width &&
>  		    mode->mode_info.vdisplay == target_mode->height) {
> -			if (mode->mode_info.vrefresh == target_mode->refresh || 
> +			if (mode->base.refresh == target_mode->refresh ||

Definitely wrong in the current form, but I'm mildly concerned that the
math used to calculate mode->base.refresh is not just 1000 *
mode_info.vdisplay.

For my monitor, 1280x1024 with vrefresh = 60 has a refresh = 60020
1440x900 at 60 -> 59901

Should we be trying to do a nearest match instead of an exact match?

>            		    target_mode->refresh == 0) {
>  				return mode;
>  			} else if (!tmp_mode) 
>