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drm/tegra: dc: Restore coupling of display controllers 

Coupling of display controllers used to rely on runtime PM to take the
companion controller out of reset. Commit fd67e9c6ed ("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: fd67e9c6ed ("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>
This commit is contained in:
Thierry Reding 2021-03-19 08:06:37 +01:00
parent a24f98176d
commit a31500fe70
1 changed files with 8 additions and 12 deletions
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20
drivers/gpu/drm/tegra/dc.c
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@ -2501,22 +2501,18 @@ static int tegra_dc_couple(struct tegra_dc *dc)
* 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;