If our compatible string has "simple-bus" at the end of it then the system will handle probing our children for us. Doing this has a few advantages:
1. If we defer we don't have to keep probing / removing our children which should speed up boot. The system just probes them once.
2. It fixes a problem where we could get into a big loop where we'd have: - msm_pdev_probe() is called. - msm_pdev_probe() registers drivers. Registering drivers kicks off processing of probe deferrals. - component_master_add_with_match() could return -EPROBE_DEFER. making msm_pdev_probe() return -EPROBE_DEFER. - When msm_pdev_probe() returned the processing of probe deferrals happens. - Loop back to the start.
Signed-off-by: Douglas Anderson dianders@chromium.org ---
drivers/gpu/drm/msm/msm_drv.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/msm/msm_drv.c b/drivers/gpu/drm/msm/msm_drv.c index 78b09fde9e29..f7c6ef147095 100644 --- a/drivers/gpu/drm/msm/msm_drv.c +++ b/drivers/gpu/drm/msm/msm_drv.c @@ -1208,10 +1208,18 @@ static int add_display_components(struct device *dev, if (of_device_is_compatible(dev->of_node, "qcom,mdss") || of_device_is_compatible(dev->of_node, "qcom,sdm845-mdss") || of_device_is_compatible(dev->of_node, "qcom,sc7180-mdss")) { - ret = devm_of_platform_populate(dev); - if (ret) { - DRM_DEV_ERROR(dev, "failed to populate children devices\n"); - return ret; + /* + * Old device tree files didn't include "simple-bus" + * in their compatible string so we had to manually pouplate + * our children. When existing device trees are fixed this + * can be removed. + */ + if (!of_device_is_compatible(dev->of_node, "simple-bus")) { + ret = devm_of_platform_populate(dev); + if (ret) { + DRM_DEV_ERROR(dev, "failed to populate children devices\n"); + return ret; + } }
mdp_dev = device_find_child(dev, NULL, compare_name_mdp);