linux-kernel - [PATCH] drm/vc4: Remove broken attempt at GPU reset using genpd.

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Date:	Mon, 21 Dec 2015 18:08:44 -0800
From:	Eric Anholt <eric@...olt.net>
To:	dri-devel@...ts.freedesktop.org
Cc:	linux-kernel@...r.kernel.org, David Airlie <airlied@...ux.ie>,
	Sudip Mukherjee <sudipm.mukherjee@...il.com>,
	rjw@...ysocki.net, Eric Anholt <eric@...olt.net>
Subject: [PATCH] drm/vc4: Remove broken attempt at GPU reset using genpd.

I've tested and confirmed that it doesn't actually work.  We'll need
to sort out how to do this properly later, but for now just remove it
since it also caused build breakage due to using CONFIG_PM_SLEEP
functions without our Kconfig depending on PM_SLEEP.

Signed-off-by: Eric Anholt <eric@...olt.net>
---
 drivers/gpu/drm/vc4/vc4_v3d.c | 17 +++++++----------
 1 file changed, 7 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/vc4/vc4_v3d.c b/drivers/gpu/drm/vc4/vc4_v3d.c
index 424d515..314ff71 100644
--- a/drivers/gpu/drm/vc4/vc4_v3d.c
+++ b/drivers/gpu/drm/vc4/vc4_v3d.c
@@ -144,19 +144,16 @@ int vc4_v3d_debugfs_ident(struct seq_file *m, void *unused)
 }
 #endif /* CONFIG_DEBUG_FS */
 
-/*
- * Asks the firmware to turn on power to the V3D engine.
- *
- * This may be doable with just the clocks interface, though this
- * packet does some other register setup from the firmware, too.
- */
 int
 vc4_v3d_set_power(struct vc4_dev *vc4, bool on)
 {
-	if (on)
-		return pm_generic_poweroff(&vc4->v3d->pdev->dev);
-	else
-		return pm_generic_resume(&vc4->v3d->pdev->dev);
+	/* XXX: This interface is needed for GPU reset, and the way to
+	 * do it is to turn our power domain off and back on.  We
+	 * can't just reset from within the driver, because the reset
+	 * bits are in the power domain's register area, and get set
+	 * during the poweron process.
+	 */
+	return 0;
 }
 
 static void vc4_v3d_init_hw(struct drm_device *dev)
-- 
2.6.2

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