linux-kernel - [PATCH 2/2] mmc: dw_mmc: Give a good reset after we give power

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Message-Id: <1424458639-23330-2-git-send-email-dianders@chromium.org>
Date:	Fri, 20 Feb 2015 10:57:19 -0800
From:	Doug Anderson <dianders@...omium.org>
To:	Jaehoon Chung <jh80.chung@...sung.com>,
	Seungwon Jeon <tgih.jun@...sung.com>,
	Ulf Hansson <ulf.hansson@...aro.org>
Cc:	Alim Akhtar <alim.akhtar@...sung.com>,
	Sonny Rao <sonnyrao@...omium.org>,
	Andrew Bresticker <abrestic@...omium.org>,
	Heiko Stuebner <heiko@...ech.de>,
	Addy Ke <addy.ke@...k-chips.com>,
	Alexandru Stan <amstan@...omium.org>,
	javier.martinez@...labora.co.uk,
	Doug Anderson <dianders@...omium.org>, chris@...ntf.net,
	linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 2/2] mmc: dw_mmc: Give a good reset after we give power

We should give dw_mmc a good reset after we apply power.  On some
boards vqmmc may actually be connected to the IP block in the SoC so
it's good to reset after power comes in.

Without this we sometimes see failures enumerating cards on rk3288.

Signed-off-by: Doug Anderson <dianders@...omium.org>
---
 drivers/mmc/host/dw_mmc.c | 27 ++++++++++++++++++---------
 1 file changed, 18 insertions(+), 9 deletions(-)

diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
index 43fcae1..6a712ae 100644
--- a/drivers/mmc/host/dw_mmc.c
+++ b/drivers/mmc/host/dw_mmc.c
@@ -1119,13 +1119,23 @@ static void dw_mci_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
 		mci_writel(slot->host, PWREN, regs);
 		break;
 	case MMC_POWER_ON:
-		if (!IS_ERR(mmc->supply.vqmmc) && !slot->host->vqmmc_enabled) {
-			ret = regulator_enable(mmc->supply.vqmmc);
-			if (ret < 0)
-				dev_err(slot->host->dev,
-					"failed to enable vqmmc regulator\n");
-			else
+		if (!slot->host->vqmmc_enabled) {
+			if (!IS_ERR(mmc->supply.vqmmc)) {
+				ret = regulator_enable(mmc->supply.vqmmc);
+				if (ret < 0)
+					dev_err(slot->host->dev,
+						"failed to enable vqmmc\n");
+				else
+					slot->host->vqmmc_enabled = true;
+
+			} else {
+				/* Keep track so we don't reset again */
 				slot->host->vqmmc_enabled = true;
+			}
+
+			/* Reset our state machine after powering on */
+			dw_mci_ctrl_reset(slot->host,
+					  SDMMC_CTRL_ALL_RESET_FLAGS);
 		}
 
 		/* Adjust clock / bus width after power is up */
@@ -1139,10 +1149,9 @@ static void dw_mci_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
 		if (!IS_ERR(mmc->supply.vmmc))
 			mmc_regulator_set_ocr(mmc, mmc->supply.vmmc, 0);
 
-		if (!IS_ERR(mmc->supply.vqmmc) && slot->host->vqmmc_enabled) {
+		if (!IS_ERR(mmc->supply.vqmmc) && slot->host->vqmmc_enabled)
 			regulator_disable(mmc->supply.vqmmc);
-			slot->host->vqmmc_enabled = false;
-		}
+		slot->host->vqmmc_enabled = false;
 
 		regs = mci_readl(slot->host, PWREN);
 		regs &= ~(1 << slot->id);
-- 
2.2.0.rc0.207.ga3a616c

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