linux-kernel - [PATCH v4 17/22] drm/sun4i: Move access control before setting the register as documented

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Date:   Wed,  5 Dec 2018 09:36:58 +0100
From:   Paul Kocialkowski <paul.kocialkowski@...tlin.com>
To:     dri-devel@...ts.freedesktop.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Cc:     Maxime Ripard <maxime.ripard@...tlin.com>,
        David Airlie <airlied@...ux.ie>, Chen-Yu Tsai <wens@...e.org>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Sean Paul <sean@...rly.run>,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
        linux-sunxi@...glegroups.com, Daniel Vetter <daniel@...ll.ch>,
        Paul Kocialkowski <paul.kocialkowski@...tlin.com>
Subject: [PATCH v4 17/22] drm/sun4i: Move access control before setting the register as documented

From: Maxime Ripard <maxime.ripard@...tlin.com>

Unlike what is currently being done, the ACCESS_CTRL bit documentation asks
that this bit should be set before modifying any register. The code in the
BSP also does this, so make sure we do this as well.

Signed-off-by: Maxime Ripard <maxime.ripard@...tlin.com>
Signed-off-by: Paul Kocialkowski <paul.kocialkowski@...tlin.com>
---
 drivers/gpu/drm/sun4i/sun4i_frontend.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/sun4i/sun4i_frontend.c b/drivers/gpu/drm/sun4i/sun4i_frontend.c
index 1153539f3aef..88ac77518610 100644
--- a/drivers/gpu/drm/sun4i/sun4i_frontend.c
+++ b/drivers/gpu/drm/sun4i/sun4i_frontend.c
@@ -75,6 +75,10 @@ static void sun4i_frontend_scaler_init(struct sun4i_frontend *frontend)
 {
 	int i;
 
+	regmap_write_bits(frontend->regs, SUN4I_FRONTEND_FRM_CTRL_REG,
+			  SUN4I_FRONTEND_FRM_CTRL_COEF_ACCESS_CTRL,
+			  SUN4I_FRONTEND_FRM_CTRL_COEF_ACCESS_CTRL);
+
 	for (i = 0; i < 32; i++) {
 		regmap_write(frontend->regs, SUN4I_FRONTEND_CH0_HORZCOEF0_REG(i),
 			     sun4i_frontend_horz_coef[2 * i]);
@@ -90,9 +94,6 @@ static void sun4i_frontend_scaler_init(struct sun4i_frontend *frontend)
 			     sun4i_frontend_vert_coef[i]);
 	}
 
-	regmap_update_bits(frontend->regs, SUN4I_FRONTEND_FRM_CTRL_REG,
-			   SUN4I_FRONTEND_FRM_CTRL_COEF_ACCESS_CTRL,
-			   SUN4I_FRONTEND_FRM_CTRL_COEF_ACCESS_CTRL);
 }
 
 int sun4i_frontend_init(struct sun4i_frontend *frontend)
-- 
2.19.2