drm/i915/fbdev: Stop repeating tile configuration on stagnation

If we cease making progress in finding matching outputs for a tiled
configuration, stop looping over the remaining unconfigured outputs.

v2: Use conn_seq (instead of pass) to only apply tile configuration on
first pass.

Fixes: b0ee9e7fa5b4 ("drm/fb: add support for tiled monitor configurations. (v2)")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tomasz Lis <tomasz.lis@intel.com>
Cc: Dave Airlie <airlied@redhat.com>
Cc: Daniel Vetter <daniel.vetter@intel.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Sean Paul <seanpaul@chromium.org>
Cc: <stable@vger.kernel.org> # v3.19+
Reviewed-by: Tomasz Lis <tomasz.lis@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170224114306.4400-1-chris@chris-wilson.co.uk
(cherry picked from commit 754a76591b12c88f57ad8b4ca533a5c9566a1922)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

diff --git a/drivers/gpu/drm/i915/intel_fbdev.c b/drivers/gpu/drm/i915/intel_fbdev.c
index 1b8ba2e..2d449fb 100644 (file)
--- a/drivers/gpu/drm/i915/intel_fbdev.c
+++ b/drivers/gpu/drm/i915/intel_fbdev.c
@@ -357,14 +357,13 @@ static bool intel_fb_initial_config(struct drm_fb_helper *fb_helper,
                                    bool *enabled, int width, int height)
 {
        struct drm_i915_private *dev_priv = to_i915(fb_helper->dev);
-       unsigned long conn_configured, mask;
+       unsigned long conn_configured, conn_seq, mask;
        unsigned int count = min(fb_helper->connector_count, BITS_PER_LONG);
        int i, j;
        bool *save_enabled;
        bool fallback = true;
        int num_connectors_enabled = 0;
        int num_connectors_detected = 0;
-       int pass = 0;
 
        save_enabled = kcalloc(count, sizeof(bool), GFP_KERNEL);
        if (!save_enabled)
@@ -374,6 +373,7 @@ static bool intel_fb_initial_config(struct drm_fb_helper *fb_helper,
        mask = BIT(count) - 1;
        conn_configured = 0;
 retry:
+       conn_seq = conn_configured;
        for (i = 0; i < count; i++) {
                struct drm_fb_helper_connector *fb_conn;
                struct drm_connector *connector;
@@ -387,7 +387,7 @@ retry:
                if (conn_configured & BIT(i))
                        continue;
 
-               if (pass == 0 && !connector->has_tile)
+               if (conn_seq == 0 && !connector->has_tile)
                        continue;
 
                if (connector->status == connector_status_connected)
@@ -498,10 +498,8 @@ retry:
                conn_configured |= BIT(i);
        }
 
-       if ((conn_configured & mask) != mask) {
-               pass++;
+       if ((conn_configured & mask) != mask && conn_configured != conn_seq)
                goto retry;
-       }
 
        /*
         * If the BIOS didn't enable everything it could, fall back to have the