This is a note to let you know that I've just added the patch titled drm/tegra: dc: Restore coupling of display controllers to the 5.11-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: drm-tegra-dc-restore-coupling-of-display-controllers.patch and it can be found in the queue-5.11 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From a31500fe7055451ed9043c8fff938dfa6f70ee37 Mon Sep 17 00:00:00 2001 From: Thierry Reding <treding@xxxxxxxxxx> Date: Fri, 19 Mar 2021 08:06:37 +0100 Subject: drm/tegra: dc: Restore coupling of display controllers From: Thierry Reding <treding@xxxxxxxxxx> commit a31500fe7055451ed9043c8fff938dfa6f70ee37 upstream. Coupling of display controllers used to rely on runtime PM to take the companion controller out of reset. Commit fd67e9c6ed5a ("drm/tegra: Do not implement runtime PM") accidentally broke this when runtime PM was removed. Restore this functionality by reusing the hierarchical host1x client suspend/resume infrastructure that's similar to runtime PM and which perfectly fits this use-case. Fixes: fd67e9c6ed5a ("drm/tegra: Do not implement runtime PM") Reported-by: Dmitry Osipenko <digetx@xxxxxxxxx> Reported-by: Paul Fertser <fercerpav@xxxxxxxxx> Tested-by: Dmitry Osipenko <digetx@xxxxxxxxx> Signed-off-by: Thierry Reding <treding@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/gpu/drm/tegra/dc.c | 20 ++++++++------------ 1 file changed, 8 insertions(+), 12 deletions(-) --- a/drivers/gpu/drm/tegra/dc.c +++ b/drivers/gpu/drm/tegra/dc.c @@ -2501,22 +2501,18 @@ static int tegra_dc_couple(struct tegra_ * POWER_CONTROL registers during CRTC enabling. */ if (dc->soc->coupled_pm && dc->pipe == 1) { - u32 flags = DL_FLAG_PM_RUNTIME | DL_FLAG_AUTOREMOVE_CONSUMER; - struct device_link *link; - struct device *partner; + struct device *companion; + struct tegra_dc *parent; - partner = driver_find_device(dc->dev->driver, NULL, NULL, - tegra_dc_match_by_pipe); - if (!partner) + companion = driver_find_device(dc->dev->driver, NULL, (const void *)0, + tegra_dc_match_by_pipe); + if (!companion) return -EPROBE_DEFER; - link = device_link_add(dc->dev, partner, flags); - if (!link) { - dev_err(dc->dev, "failed to link controllers\n"); - return -EINVAL; - } + parent = dev_get_drvdata(companion); + dc->client.parent = &parent->client; - dev_dbg(dc->dev, "coupled to %s\n", dev_name(partner)); + dev_dbg(dc->dev, "coupled to %s\n", dev_name(companion)); } return 0; Patches currently in stable-queue which might be from treding@xxxxxxxxxx are queue-5.11/drm-tegra-dc-restore-coupling-of-display-controllers.patch queue-5.11/drm-tegra-sor-grab-runtime-pm-reference-across-reset.patch