linux-kernel - [PATCH 1/5] mmc: sdhci: add quirk for R/W Transfer Active EOT

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Message-Id: <1376577140-2652-2-git-send-email-gdjakov@mm-sol.com>
Date:	Thu, 15 Aug 2013 17:32:16 +0300
From:	Georgi Djakov <gdjakov@...sol.com>
To:	cjb@...top.org
Cc:	linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org,
	Georgi Djakov <gdjakov@...sol.com>,
	Venkat Gopalakrishnan <venkatg@...eaurora.org>,
	Asutosh Das <asutoshd@...eaurora.org>,
	Sahitya Tummala <stummala@...eaurora.org>
Subject: [PATCH 1/5] mmc: sdhci: add quirk for R/W Transfer Active EOT

Initial version of Qualcomm SDHC has a hardware issue. This patch adds
a quirk SDHCI_QUIRK2_RDWR_TX_ACTIVE_EOT to enable a workaround.

Hardware issue: Read Transfer Active/ Write Transfer Active may be
not de-asserted after end of transaction.

Software workaround: Set Software Reset for DAT line in Software Reset
Register (Bit 2).

CC: Venkat Gopalakrishnan <venkatg@...eaurora.org>
CC: Asutosh Das <asutoshd@...eaurora.org>
CC: Sahitya Tummala <stummala@...eaurora.org>
Signed-off-by: Georgi Djakov <gdjakov@...sol.com>
---
 drivers/mmc/host/sdhci.c  |    3 +++
 include/linux/mmc/sdhci.h |    2 ++
 2 files changed, 5 insertions(+)

diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index a78bd4f..57659fb 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -2155,6 +2155,9 @@ static void sdhci_tasklet_finish(unsigned long param)
 		   controllers do not like that. */
 		sdhci_reset(host, SDHCI_RESET_CMD);
 		sdhci_reset(host, SDHCI_RESET_DATA);
+	} else {
+		if (host->quirks2 & SDHCI_QUIRK2_RDWR_TX_ACTIVE_EOT)
+			sdhci_reset(host, SDHCI_RESET_DATA);
 	}
 
 	host->mrq = NULL;
diff --git a/include/linux/mmc/sdhci.h b/include/linux/mmc/sdhci.h
index e3c6a74..3783f4c 100644
--- a/include/linux/mmc/sdhci.h
+++ b/include/linux/mmc/sdhci.h
@@ -98,6 +98,8 @@ struct sdhci_host {
 #define SDHCI_QUIRK2_CARD_ON_NEEDS_BUS_ON		(1<<4)
 /* Controller has a non-standard host control register */
 #define SDHCI_QUIRK2_BROKEN_HOST_CONTROL		(1<<5)
+/* Controller cannot de-assert Read/Write Transfer Active after transaction */
+#define SDHCI_QUIRK2_RDWR_TX_ACTIVE_EOT		(1<<6)
 
 	int irq;		/* Device IRQ */
 	void __iomem *ioaddr;	/* Mapped address */
-- 
1.7.9.5

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