linux-kernel - [PATCH v2 7/8] imx-drm: ipuv3-crtc: Change display enable/disable order

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Date:	Mon, 14 Apr 2014 23:53:22 +0200
From:	Philipp Zabel <p.zabel@...gutronix.de>
To:	devel@...verdev.osuosl.org,
	Russell King <rmk+kernel@....linux.org.uk>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
	kernel@...gutronix.de, Philipp Zabel <p.zabel@...gutronix.de>
Subject: [PATCH v2 7/8] imx-drm: ipuv3-crtc: Change display enable/disable order

Now that ipu_dc_disable_channel correctly waits for the channel to finish,
we can reorder the enable/disable order to first stop the DC and DI and
only then disable the IDMAC. Enabling is done the other way around: IDMAC
first, then DC, then DI.

This avoids an issue where sometimes the channel would not correctly start,
leading to non-working LVDS displays.

Signed-off-by: Philipp Zabel <p.zabel@...gutronix.de>
---
 drivers/staging/imx-drm/ipuv3-crtc.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/staging/imx-drm/ipuv3-crtc.c b/drivers/staging/imx-drm/ipuv3-crtc.c
index c48f640..c771ac1 100644
--- a/drivers/staging/imx-drm/ipuv3-crtc.c
+++ b/drivers/staging/imx-drm/ipuv3-crtc.c
@@ -63,9 +63,11 @@ static void ipu_fb_enable(struct ipu_crtc *ipu_crtc)
 	if (ipu_crtc->enabled)
 		return;
 
-	ipu_di_enable(ipu_crtc->di);
-	ipu_dc_enable_channel(ipu_crtc->dc);
+	/* TODO: Enable DC module here, right now it is never disabled */
 	ipu_plane_enable(ipu_crtc->plane[0]);
+	/* Start DC channel and DI after IDMAC */
+	ipu_dc_enable_channel(ipu_crtc->dc);
+	ipu_di_enable(ipu_crtc->di);
 
 	ipu_crtc->enabled = 1;
 }
@@ -75,9 +77,11 @@ static void ipu_fb_disable(struct ipu_crtc *ipu_crtc)
 	if (!ipu_crtc->enabled)
 		return;
 
-	ipu_plane_disable(ipu_crtc->plane[0]);
+	/* Stop DC channel and DI before IDMAC */
 	ipu_dc_disable_channel(ipu_crtc->dc);
 	ipu_di_disable(ipu_crtc->di);
+	ipu_plane_disable(ipu_crtc->plane[0]);
+	/* TODO: Disable DC module here */
 
 	ipu_crtc->enabled = 0;
 }
-- 
1.9.1

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