linux-kernel - [PATCH v10 06/11] drm: bridge/dw_hdmi: clear i2cmphy_stat0 reg in hdmi_phy_wait_i2c

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Message-Id: <1415935679-16874-1-git-send-email-andy.yan@rock-chips.com>
Date:	Fri, 14 Nov 2014 11:27:59 +0800
From:	Andy Yan <andy.yan@...k-chips.com>
To:	airlied@...ux.ie, heiko@...ech.de, fabio.estevam@...escale.com,
	rmk+kernel@....linux.org.uk
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Grant Likely <grant.likely@...aro.org>,
	Rob Herring <robh+dt@...nel.org>,
	Philipp Zabel <p.zabel@...gutronix.de>,
	Shawn Guo <shawn.guo@...aro.org>,
	Josh Boyer <jwboyer@...hat.com>,
	Sean Paul <seanpaul@...omium.org>,
	Inki Dae <inki.dae@...sung.com>,
	Dave Airlie <airlied@...hat.com>,
	Arnd Bergmann <arnd@...db.de>,
	Lucas Stach <l.stach@...gutronix.de>,
	Zubair.Kakakhel@...tec.com, djkurtz@...gle.com, ykk@...k-chips.com,
	linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
	devel@...verdev.osuosl.org, devicetree@...r.kernel.org,
	linux-rockchip@...ts.infradead.org, jay.xu@...k-chips.com,
	Pawel Moll <pawel.moll@....com>, mark.yao@...k-chips.com,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	Andy Yan <andy.yan@...k-chips.com>
Subject: [PATCH v10 06/11] drm: bridge/dw_hdmi: clear i2cmphy_stat0 reg in hdmi_phy_wait_i2c_done

HDMI_IH_I2CMPHY_STAT0 is a clear on write register, which indicates i2cm
operation status(i2c transfer done or error), every hdmi phy register
configuration must check this register to make sure the configuration
has complete. But the indication bit should be cleared after check, otherwise
the corresponding bit will hold on forever, this may give a wrong signal for
next check.

Signed-off-by: Andy Yan <andy.yan@...k-chips.com>
---

Changes in v10: None
Changes in v9: None
Changes in v8: None
Changes in v7: None
Changes in v6: None
Changes in v5: None
Changes in v4: None
Changes in v3: None
Changes in v2: None

 drivers/gpu/drm/bridge/dw_hdmi.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/bridge/dw_hdmi.c b/drivers/gpu/drm/bridge/dw_hdmi.c
index 05e7156..4f9a5c0 100644
--- a/drivers/gpu/drm/bridge/dw_hdmi.c
+++ b/drivers/gpu/drm/bridge/dw_hdmi.c
@@ -640,11 +640,15 @@ static inline void hdmi_phy_test_dout(struct dw_hdmi *hdmi,
 
 static bool hdmi_phy_wait_i2c_done(struct dw_hdmi *hdmi, int msec)
 {
-	while ((hdmi_readb(hdmi, HDMI_IH_I2CMPHY_STAT0) & 0x3) == 0) {
+	u32 val;
+
+	while ((val = hdmi_readb(hdmi, HDMI_IH_I2CMPHY_STAT0) & 0x3) == 0) {
 		if (msec-- == 0)
 			return false;
 		udelay(1000);
 	}
+	hdmi_writeb(hdmi, val, HDMI_IH_I2CMPHY_STAT0);
+
 	return true;
 }
 
-- 
1.9.1

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