linux-kernel - [PATCH 2/3] mmc: sdhci_am654: Reset Command and Data line after tuning

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Date:   Wed, 8 Jan 2020 20:03:00 +0530
From:   Faiz Abbas <faiz_abbas@...com>
To:     <linux-kernel@...r.kernel.org>, <linux-mmc@...r.kernel.org>
CC:     <ulf.hansson@...aro.org>, <adrian.hunter@...el.com>,
        <faiz_abbas@...com>
Subject: [PATCH 2/3] mmc: sdhci_am654: Reset Command and Data line after tuning

The tuning data is leftover in the buffer after tuning. This can cause
issues in future data commands, especially with CQHCI. Reset the command
and data lines after tuning to continue from a clean state.

Fixes: 41fd4caeb00b ("mmc: sdhci_am654: Add Initial Support for AM654 SDHCI driver")
Cc: stable@...r.kernel.org
Signed-off-by: Faiz Abbas <faiz_abbas@...com>
---
 drivers/mmc/host/sdhci_am654.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/drivers/mmc/host/sdhci_am654.c b/drivers/mmc/host/sdhci_am654.c
index 2d38b1e12a7e..59c0c41b3739 100644
--- a/drivers/mmc/host/sdhci_am654.c
+++ b/drivers/mmc/host/sdhci_am654.c
@@ -240,6 +240,22 @@ static void sdhci_am654_write_b(struct sdhci_host *host, u8 val, int reg)
 	writeb(val, host->ioaddr + reg);
 }
 
+static int sdhci_am654_execute_tuning(struct mmc_host *mmc, u32 opcode)
+{
+	struct sdhci_host *host = mmc_priv(mmc);
+	int err = sdhci_execute_tuning(mmc, opcode);
+
+	if (err)
+		return err;
+	/*
+	 * Tuning data remains in the buffer after tuning.
+	 * Do a command and data reset to get rid of it
+	 */
+	sdhci_reset(host, SDHCI_RESET_CMD | SDHCI_RESET_DATA);
+
+	return 0;
+}
+
 static struct sdhci_ops sdhci_am654_ops = {
 	.get_max_clock = sdhci_pltfm_clk_get_max_clock,
 	.get_timeout_clock = sdhci_pltfm_clk_get_max_clock,
@@ -546,6 +562,8 @@ static int sdhci_am654_probe(struct platform_device *pdev)
 		goto pm_runtime_put;
 	}
 
+	host->mmc_host_ops.execute_tuning = sdhci_am654_execute_tuning;
+
 	ret = sdhci_am654_init(host);
 	if (ret)
 		goto pm_runtime_put;
-- 
2.19.2