linux-kernel - [PATCH v2 3/4] phy: rockchip-typec: Do the calibration more correctly

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Date:   Tue, 19 Sep 2017 12:56:29 -0700
From:   Douglas Anderson <dianders@...omium.org>
To:     kishon@...com, heiko@...ech.de, zyw@...k-chips.com
Cc:     groeck@...omium.org, shawnn@...omium.org, dnschneid@...omium.org,
        Douglas Anderson <dianders@...omium.org>,
        linux-rockchip@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org
Subject: [PATCH v2 3/4] phy: rockchip-typec: Do the calibration more correctly

Calculate the calibration code as per the docs.  The docs talk about
reading and averaging the pullup and pulldown calibration codes.  They
also talk about adding in some adjustment codes.  Let's do what the
docs say.

In practice this doesn't seem to matter a whole lot.  On a device I
tested the pullup and pulldown codes were nearly the same (0x23 and
0x24) and the adjustment codes were 0.

Reviewed-by: Chris Zhong <zyw@...k-chips.com>
Signed-off-by: Douglas Anderson <dianders@...omium.org>
---

Changes in v2:
- Removed extra blank line

 drivers/phy/rockchip/phy-rockchip-typec.c | 27 ++++++++++++++++++---------
 1 file changed, 18 insertions(+), 9 deletions(-)

diff --git a/drivers/phy/rockchip/phy-rockchip-typec.c b/drivers/phy/rockchip/phy-rockchip-typec.c
index b8696a7c45fb..a1f961844efe 100644
--- a/drivers/phy/rockchip/phy-rockchip-typec.c
+++ b/drivers/phy/rockchip/phy-rockchip-typec.c
@@ -560,24 +560,33 @@ static void tcphy_dp_aux_calibration(struct rockchip_typec_phy *tcphy)
 	u16 val;
 	u16 tx_ana_ctrl_reg_1;
 	u16 tx_ana_ctrl_reg_2;
-	s32 pu_calib_code;
-
-	/* disable txda_cal_latch_en for rewrite the calibration values */
-	tx_ana_ctrl_reg_1 = readl(tcphy->base + TX_ANA_CTRL_REG_1);
-	tx_ana_ctrl_reg_1 &= ~TXDA_CAL_LATCH_EN;
-	writel(tx_ana_ctrl_reg_1, tcphy->base + TX_ANA_CTRL_REG_1);
+	s32 pu_calib_code, pd_calib_code;
+	s32 pu_adj, pd_adj;
+	u16 calib;
 
 	/*
-	 * read a resistor calibration code from CMN_TXPUCAL_CTRL[5:0] and
-	 * write it to TX_DIG_CTRL_REG_2[5:0].
+	 * Calculate calibration code as per docs: use an average of the
+	 * pull down and pull up.  Then add in adjustments.
 	 */
 	val = readl(tcphy->base + CMN_TXPUCAL_CTRL);
 	pu_calib_code = CMN_CALIB_CODE_POS(val);
+	val = readl(tcphy->base + CMN_TXPDCAL_CTRL);
+	pd_calib_code = CMN_CALIB_CODE_POS(val);
+	val = readl(tcphy->base + CMN_TXPU_ADJ_CTRL);
+	pu_adj = CMN_CALIB_CODE(val);
+	val = readl(tcphy->base + CMN_TXPD_ADJ_CTRL);
+	pd_adj = CMN_CALIB_CODE(val);
+	calib = (pu_calib_code + pd_calib_code) / 2 + pu_adj + pd_adj;
+
+	/* disable txda_cal_latch_en for rewrite the calibration values */
+	tx_ana_ctrl_reg_1 = readl(tcphy->base + TX_ANA_CTRL_REG_1);
+	tx_ana_ctrl_reg_1 &= ~TXDA_CAL_LATCH_EN;
+	writel(tx_ana_ctrl_reg_1, tcphy->base + TX_ANA_CTRL_REG_1);
 
 	/* write the calibration, then delay 10 ms as sample in docs */
 	val = readl(tcphy->base + TX_DIG_CTRL_REG_2);
 	val &= ~(TX_RESCAL_CODE_MASK << TX_RESCAL_CODE_OFFSET);
-	val |= pu_calib_code << TX_RESCAL_CODE_OFFSET;
+	val |= calib << TX_RESCAL_CODE_OFFSET;
 	writel(val, tcphy->base + TX_DIG_CTRL_REG_2);
 	usleep_range(10000, 10050);
 
-- 
2.14.1.690.gbb1197296e-goog