linux-kernel - [PATCH 04/12] usb: phy: ab8500-usb: fix eye diagram for ab8500 v2.0

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Date:	Wed,  3 Apr 2013 10:45:05 +0200
From:	Fabio Baltieri <fabio.baltieri@...aro.org>
To:	Felipe Balbi <balbi@...com>
Cc:	Linus Walleij <linus.walleij@...aro.org>,
	Praveena Nadahally <praveen.nadahally@...ricsson.com>,
	linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org,
	Sakethram Bommisetti <sakethram.bommisetti@...ricsson.com>,
	Fabio Baltieri <fabio.baltieri@...aro.org>
Subject: [PATCH 04/12] usb: phy: ab8500-usb: fix eye diagram for ab8500 v2.0

From: Sakethram Bommisetti <sakethram.bommisetti@...ricsson.com>

AB8500 v2.0 has eye diagram issues when drawing more than 100mA from
VBUS.  Force charging current to 100mA in case of standard host.

Signed-off-by: Sakethram Bommisetti <sakethram.bommisetti@...ricsson.com>
Acked-by: Linus Walleij <linus.walleij@...aro.org>
Signed-off-by: Fabio Baltieri <fabio.baltieri@...aro.org>
---
 drivers/usb/phy/phy-ab8500-usb.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/drivers/usb/phy/phy-ab8500-usb.c b/drivers/usb/phy/phy-ab8500-usb.c
index 5b92a59..1fd0780 100644
--- a/drivers/usb/phy/phy-ab8500-usb.c
+++ b/drivers/usb/phy/phy-ab8500-usb.c
@@ -485,6 +485,18 @@ static void ab8500_usb_phy_disable_work(struct work_struct *work)
 		ab8500_usb_peri_phy_dis(ab);
 }
 
+static unsigned ab8500_eyediagram_workaroud(struct ab8500_usb *ab, unsigned mA)
+{
+	/* AB8500 V2 has eye diagram issues when drawing more than 100mA from
+	 * VBUS.  Set charging current to 100mA in case of standard host
+	 */
+	if (is_ab8500_2p0_or_earlier(ab->ab8500))
+		if (mA > 100)
+			mA = 100;
+
+	return mA;
+}
+
 static int ab8500_usb_set_power(struct usb_phy *phy, unsigned mA)
 {
 	struct ab8500_usb *ab;
@@ -494,6 +506,8 @@ static int ab8500_usb_set_power(struct usb_phy *phy, unsigned mA)
 
 	ab = phy_to_ab(phy);
 
+	mA = ab8500_eyediagram_workaroud(ab, mA);
+
 	ab->vbus_draw = mA;
 
 	if (mA)
-- 
1.8.1.3

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