linux-kernel - [PATCH 3/6] Unified AVR32/AT91 MCI Driver Reset Patch

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Date:	Fri, 12 Jun 2009 18:02:41 -0700
From:	Rob Emanuele <poorarm@...reis.com>
To:	Haavard Skinnemoen <haavard.skinnemoen@...el.com>
Cc:	Andrew Victor <avictor.za@...il.com>,
	Nicolas Ferre <nicolas.ferre@...el.com>,
	linux-arm-kernel@...ts.arm.linux.org.uk,
	linux-kernel@...r.kernel.org, drzeus-mmc@...eus.cx
Subject: [PATCH 3/6] Unified AVR32/AT91 MCI Driver Reset Patch

This patch adds the compile time configuration option for the
atmel-mci driver to reset the Atmel MCI controller before every
command.

This is sometimes needed for the Atmel controller / board to function
properly.  In the case of the at91sam9g20-ek this is needed.

Please read the whole set, try it out, and comment.

Thank you,

Rob Emanuele

---
 drivers/mmc/host/Kconfig     |   10 ++++++++++
 drivers/mmc/host/atmel-mci.c |   11 ++++++++++-
 2 files changed, 20 insertions(+), 1 deletions(-)

diff --git a/drivers/mmc/host/Kconfig b/drivers/mmc/host/Kconfig
index 6e2f52b..9e24029 100644
--- a/drivers/mmc/host/Kconfig
+++ b/drivers/mmc/host/Kconfig
@@ -150,6 +150,16 @@ config MMC_ATMELMCI

 endchoice

+config MMC_ATMELMCI_ALWAYS_RESET
+	bool "Reset before every request.  Sometimes needed for buggy chips."
+	depends on MMC_ATMELMCI
+	help
+	  There are reports that some buggy controllers work better
+	  with a reset before every command.  This may improve your
+	  controller's reliability.
+
+	  If unsure, say N.
+
 config MMC_ATMELMCI_DMA
 	bool "Atmel MCI DMA support (EXPERIMENTAL)"
 	depends on MMC_ATMELMCI && AVR32 && DMA_ENGINE && EXPERIMENTAL
diff --git a/drivers/mmc/host/atmel-mci.c b/drivers/mmc/host/atmel-mci.c
index 497dd51..b133baa 100644
--- a/drivers/mmc/host/atmel-mci.c
+++ b/drivers/mmc/host/atmel-mci.c
@@ -65,6 +65,15 @@ struct atmel_mci_dma {
 #endif
 };

+/*
+ * Configuration options from the kernel config
+ */
+#ifdef CONFIG_MMC_ATMELMCI_ALWAYS_RESET
+#define MMC_ALWAYS_RESET 1
+#else
+#define MMC_ALWAYS_RESET 0
+#endif
+
 /**
  * struct atmel_mci - MMC controller state shared between all slots
  * @lock: Spinlock protecting the queue and associated data.
@@ -714,7 +723,7 @@ static void atmci_start_request(struct atmel_mci *host,
 	host->completed_events = 0;
 	host->data_status = 0;

-	if (host->need_reset) {
+	if (host->need_reset || MMC_ALWAYS_RESET) {
 		mci_writel(host, CR, MCI_CR_SWRST);
 		mci_writel(host, CR, MCI_CR_MCIEN);
 		mci_writel(host, MR, host->mode_reg);
-- 
1.6.0.4
--
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