[PATCH 5.10 078/126] drm/tegra: dc: Restore coupling of display controllers

Greg Kroah-Hartman
2021-04-05T09:15:31Z

From: Thierry Reding <treding@nvidia.com>

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@gmail.com>
Reported-by: Paul Fertser <fercerpav@gmail.com>
Tested-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
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
@@ -2499,22 +2499,18 @@ 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;