From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Jernej Skrabec To: robh+dt@kernel.org, maxime.ripard@bootlin.com, wens@csie.org Cc: mark.rutland@arm.com, mturquette@baylibre.com, sboyd@kernel.org, airlied@linux.ie, architt@codeaurora.org, a.hajda@samsung.com, jernej.skrabec@siol.net, devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-clk@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-sunxi@googlegroups.com Subject: [PATCH 22/27] drm/sun4i: Initialize registers in tcon-top driver Date: Sun, 2 Sep 2018 09:26:38 +0200 Message-Id: <20180902072643.4917-23-jernej.skrabec@siol.net> In-Reply-To: <20180902072643.4917-1-jernej.skrabec@siol.net> References: <20180902072643.4917-1-jernej.skrabec@siol.net> List-ID: It turns out that TCON TOP registers in H6 SoC have non-zero reset value. This may cause issues if bits are not changed during configuration. To prevent that, initialize registers to 0. Signed-off-by: Jernej Skrabec --- drivers/gpu/drm/sun4i/sun8i_tcon_top.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/drivers/gpu/drm/sun4i/sun8i_tcon_top.c b/drivers/gpu/drm/sun4i/sun8i_tcon_top.c index 3040a79f298f..37158548b447 100644 --- a/drivers/gpu/drm/sun4i/sun8i_tcon_top.c +++ b/drivers/gpu/drm/sun4i/sun8i_tcon_top.c @@ -167,6 +167,13 @@ static int sun8i_tcon_top_bind(struct device *dev, struct device *master, goto err_assert_reset; } + /* + * At least on H6, some registers have some bits set by default + * which may cause issues. Clear them here. + */ + writel(0, regs + TCON_TOP_PORT_SEL_REG); + writel(0, regs + TCON_TOP_GATE_SRC_REG); + /* * TCON TOP has two muxes, which select parent clock for each TCON TV * channel clock. Parent could be either TCON TV or TVE clock. For now -- 2.18.0