linux-kernel - [PATCH v3 1/2] phy: rockchip-emmc: retry calpad busy trimming

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Message-Id: <1515638427-15117-2-git-send-email-wxt@rock-chips.com>
Date:   Thu, 11 Jan 2018 10:40:26 +0800
From:   Caesar Wang <wxt@...k-chips.com>
To:     Kishon Vijay Abraham I <kishon@...com>
Cc:     Brian Norris <briannorris@...omium.org>,
        Douglas Anderson <dianders@...omium.org>,
        Shawn Lin <shawn.lin@...k-chips.com>,
        Caesar Wang <wxt@...k-chips.com>,
        Heiko Stuebner <heiko@...ech.de>, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-rockchip@...ts.infradead.org
Subject: [PATCH v3 1/2] phy: rockchip-emmc: retry calpad busy trimming

From: Shawn Lin <shawn.lin@...k-chips.com>

It turns out that 5us isn't enough for all cases, so let's
retry some more times to wait for caldone.

Signed-off-by: Shawn Lin <shawn.lin@...k-chips.com>
Tested-by: Ziyuan Xu <xzy.xu@...k-chips.com>
Signed-off-by: Caesar Wang <wxt@...k-chips.com>
---

Changes in v3:
- As Doug commented on both upstream and gerrit.
  Change "5, 50" to "0, 50", and the message of print.

Changes in v2:
- print the return valut with regmap_read_poll_timeout failing.

 drivers/phy/rockchip/phy-rockchip-emmc.c | 27 +++++++++++++++++----------
 1 file changed, 17 insertions(+), 10 deletions(-)

diff --git a/drivers/phy/rockchip/phy-rockchip-emmc.c b/drivers/phy/rockchip/phy-rockchip-emmc.c
index f1b24f1..b0d1093 100644
--- a/drivers/phy/rockchip/phy-rockchip-emmc.c
+++ b/drivers/phy/rockchip/phy-rockchip-emmc.c
@@ -76,6 +76,10 @@
 #define PHYCTRL_OTAPDLYSEL_MASK		0xf
 #define PHYCTRL_OTAPDLYSEL_SHIFT	0x7
 
+#define PHYCTRL_IS_CALDONE(x) \
+	((((x) >> PHYCTRL_CALDONE_SHIFT) & \
+	  PHYCTRL_CALDONE_MASK) == PHYCTRL_CALDONE_DONE)
+
 struct rockchip_emmc_phy {
 	unsigned int	reg_offset;
 	struct regmap	*reg_base;
@@ -90,6 +94,7 @@ static int rockchip_emmc_phy_power(struct phy *phy, bool on_off)
 	unsigned int freqsel = PHYCTRL_FREQSEL_200M;
 	unsigned long rate;
 	unsigned long timeout;
+	int ret;
 
 	/*
 	 * Keep phyctrl_pdb and phyctrl_endll low to allow
@@ -160,17 +165,19 @@ static int rockchip_emmc_phy_power(struct phy *phy, bool on_off)
 				   PHYCTRL_PDB_SHIFT));
 
 	/*
-	 * According to the user manual, it asks driver to
-	 * wait 5us for calpad busy trimming
+	 * According to the user manual, it asks driver to wait 5us for
+	 * calpad busy trimming. However it is documented that this value is
+	 * PVT(A.K.A process,voltage and temperature) relevant, so some
+	 * failure cases are found which indicates we should be more tolerant
+	 * to calpad busy trimming.
 	 */
-	udelay(5);
-	regmap_read(rk_phy->reg_base,
-		    rk_phy->reg_offset + GRF_EMMCPHY_STATUS,
-		    &caldone);
-	caldone = (caldone >> PHYCTRL_CALDONE_SHIFT) & PHYCTRL_CALDONE_MASK;
-	if (caldone != PHYCTRL_CALDONE_DONE) {
-		pr_err("rockchip_emmc_phy_power: caldone timeout.\n");
-		return -ETIMEDOUT;
+	ret = regmap_read_poll_timeout(rk_phy->reg_base,
+				       rk_phy->reg_offset + GRF_EMMCPHY_STATUS,
+				       caldone, PHYCTRL_IS_CALDONE(caldone),
+				       0, 50);
+	if (ret) {
+		pr_err("%s: caldone failed, ret=%d\n", __func__, ret);
+		return ret;
 	}
 
 	/* Set the frequency of the DLL operation */
-- 
2.7.4