From 94b2b9670eb5e0af73bd98a991bee9856fe0e654 Mon Sep 17 00:00:00 2001
From: Steve Sakoman <steve@sakoman.com>
Date: Fri, 19 Nov 2010 15:11:19 -0800
Subject: [PATCH 11/30] Revert "omap_hsmmc: improve interrupt synchronisation"

This reverts commit b417577d3b9bbb06a4ddc9aa955af9bd503f7242.

Conflicts:

	drivers/mmc/host/omap_hsmmc.c
---
 drivers/mmc/host/omap_hsmmc.c |  267 ++++++++++++++++++++---------------------
 1 files changed, 128 insertions(+), 139 deletions(-)

diff --git a/drivers/mmc/host/omap_hsmmc.c b/drivers/mmc/host/omap_hsmmc.c
index 259ece0..15a023b 100644
--- a/drivers/mmc/host/omap_hsmmc.c
+++ b/drivers/mmc/host/omap_hsmmc.c
@@ -159,10 +159,12 @@ struct omap_hsmmc_host {
 	 */
 	struct	regulator	*vcc;
 	struct	regulator	*vcc_aux;
+	struct	semaphore	sem;
 	struct	work_struct	mmc_carddetect_work;
 	void	__iomem		*base;
 	resource_size_t		mapbase;
 	spinlock_t		irq_lock; /* Prevent races with irq handler */
+	unsigned long		flags;
 	unsigned int		id;
 	unsigned int		dma_len;
 	unsigned int		dma_sg_idx;
@@ -183,7 +185,6 @@ struct omap_hsmmc_host {
 	int			protect_card;
 	int			reqs_blocked;
 	int			use_reg;
-	int			req_in_progress;
 
 	struct	omap_mmc_platform_data	*pdata;
 };
@@ -556,32 +557,6 @@ static void omap_hsmmc_stop_clock(struct omap_hsmmc_host *host)
 		dev_dbg(mmc_dev(host->mmc), "MMC Clock is not stoped\n");
 }
 
-static void omap_hsmmc_enable_irq(struct omap_hsmmc_host *host,
-				  struct mmc_command *cmd)
-{
-	unsigned int irq_mask;
-
-	if (host->use_dma)
-		irq_mask = INT_EN_MASK & ~(BRR_ENABLE | BWR_ENABLE);
-	else
-		irq_mask = INT_EN_MASK;
-
-	/* Disable timeout for erases */
-	if (cmd->opcode == MMC_ERASE)
-		irq_mask &= ~DTO_ENABLE;
-
-	OMAP_HSMMC_WRITE(host->base, STAT, STAT_CLEAR);
-	OMAP_HSMMC_WRITE(host->base, ISE, irq_mask);
-	OMAP_HSMMC_WRITE(host->base, IE, irq_mask);
-}
-
-static void omap_hsmmc_disable_irq(struct omap_hsmmc_host *host)
-{
-	OMAP_HSMMC_WRITE(host->base, ISE, 0);
-	OMAP_HSMMC_WRITE(host->base, IE, 0);
-	OMAP_HSMMC_WRITE(host->base, STAT, STAT_CLEAR);
-}
-
 #ifdef CONFIG_PM
 
 /*
@@ -650,7 +625,9 @@ static int omap_hsmmc_context_restore(struct omap_hsmmc_host *host)
 		&& time_before(jiffies, timeout))
 		;
 
-	omap_hsmmc_disable_irq(host);
+	OMAP_HSMMC_WRITE(host->base, STAT, STAT_CLEAR);
+	OMAP_HSMMC_WRITE(host->base, ISE, INT_EN_MASK);
+	OMAP_HSMMC_WRITE(host->base, IE, INT_EN_MASK);
 
 	/* Do not initialize card-specific things if the power is off */
 	if (host->power_mode == MMC_POWER_OFF)
@@ -753,8 +730,6 @@ static void send_init_stream(struct omap_hsmmc_host *host)
 		return;
 
 	disable_irq(host->irq);
-
-	OMAP_HSMMC_WRITE(host->base, IE, INT_EN_MASK);
 	OMAP_HSMMC_WRITE(host->base, CON,
 		OMAP_HSMMC_READ(host->base, CON) | INIT_STREAM);
 	OMAP_HSMMC_WRITE(host->base, CMD, INIT_STREAM_CMD);
@@ -820,7 +795,17 @@ omap_hsmmc_start_command(struct omap_hsmmc_host *host, struct mmc_command *cmd,
 		mmc_hostname(host->mmc), cmd->opcode, cmd->arg);
 	host->cmd = cmd;
 
-	omap_hsmmc_enable_irq(host, cmd);
+	/*
+	 * Clear status bits and enable interrupts
+	 */
+	OMAP_HSMMC_WRITE(host->base, STAT, STAT_CLEAR);
+	OMAP_HSMMC_WRITE(host->base, ISE, INT_EN_MASK);
+
+	if (host->use_dma)
+		OMAP_HSMMC_WRITE(host->base, IE,
+				 INT_EN_MASK & ~(BRR_ENABLE | BWR_ENABLE));
+	else
+		OMAP_HSMMC_WRITE(host->base, IE, INT_EN_MASK);
 
 	host->response_busy = 0;
 	if (cmd->flags & MMC_RSP_PRESENT) {
@@ -854,7 +839,13 @@ omap_hsmmc_start_command(struct omap_hsmmc_host *host, struct mmc_command *cmd,
 	if (host->use_dma)
 		cmdreg |= DMA_EN;
 
-	host->req_in_progress = 1;
+	/*
+	 * In an interrupt context (i.e. STOP command), the spinlock is unlocked
+	 * by the interrupt handler, otherwise (i.e. for a new request) it is
+	 * unlocked here.
+	 */
+	if (!in_interrupt())
+		spin_unlock_irqrestore(&host->irq_lock, host->flags);
 
 	OMAP_HSMMC_WRITE(host->base, ARG, cmd->arg);
 	OMAP_HSMMC_WRITE(host->base, CMD, cmdreg);
@@ -869,23 +860,6 @@ omap_hsmmc_get_dma_dir(struct omap_hsmmc_host *host, struct mmc_data *data)
 		return DMA_FROM_DEVICE;
 }
 
-static void omap_hsmmc_request_done(struct omap_hsmmc_host *host, struct mmc_request *mrq)
-{
-	int dma_ch;
-
-	spin_lock(&host->irq_lock);
-	host->req_in_progress = 0;
-	dma_ch = host->dma_ch;
-	spin_unlock(&host->irq_lock);
-
-	omap_hsmmc_disable_irq(host);
-	/* Do not complete the request if DMA is still in progress */
-	if (mrq->data && host->use_dma && dma_ch != -1)
-		return;
-	host->mrq = NULL;
-	mmc_request_done(host->mmc, mrq);
-}
-
 /*
  * Notify the transfer complete to MMC core
  */
@@ -902,19 +876,25 @@ omap_hsmmc_xfer_done(struct omap_hsmmc_host *host, struct mmc_data *data)
 			return;
 		}
 
-		omap_hsmmc_request_done(host, mrq);
+		host->mrq = NULL;
+		mmc_request_done(host->mmc, mrq);
 		return;
 	}
 
 	host->data = NULL;
 
+	if (host->use_dma && host->dma_ch != -1)
+		dma_unmap_sg(mmc_dev(host->mmc), data->sg, host->dma_len,
+			omap_hsmmc_get_dma_dir(host, data));
+
 	if (!data->error)
 		data->bytes_xfered += data->blocks * (data->blksz);
 	else
 		data->bytes_xfered = 0;
 
 	if (!data->stop) {
-		omap_hsmmc_request_done(host, data->mrq);
+		host->mrq = NULL;
+		mmc_request_done(host->mmc, data->mrq);
 		return;
 	}
 	omap_hsmmc_start_command(host, data->stop, NULL);
@@ -940,8 +920,10 @@ omap_hsmmc_cmd_done(struct omap_hsmmc_host *host, struct mmc_command *cmd)
 			cmd->resp[0] = OMAP_HSMMC_READ(host->base, RSP10);
 		}
 	}
-	if ((host->data == NULL && !host->response_busy) || cmd->error)
-		omap_hsmmc_request_done(host, cmd->mrq);
+	if ((host->data == NULL && !host->response_busy) || cmd->error) {
+		host->mrq = NULL;
+		mmc_request_done(host->mmc, cmd->mrq);
+	}
 }
 
 /*
@@ -949,19 +931,14 @@ omap_hsmmc_cmd_done(struct omap_hsmmc_host *host, struct mmc_command *cmd)
  */
 static void omap_hsmmc_dma_cleanup(struct omap_hsmmc_host *host, int errno)
 {
-	int dma_ch;
-
 	host->data->error = errno;
 
-	spin_lock(&host->irq_lock);
-	dma_ch = host->dma_ch;
-	host->dma_ch = -1;
-	spin_unlock(&host->irq_lock);
-
-	if (host->use_dma && dma_ch != -1) {
+	if (host->use_dma && host->dma_ch != -1) {
 		dma_unmap_sg(mmc_dev(host->mmc), host->data->sg, host->dma_len,
 			omap_hsmmc_get_dma_dir(host, host->data));
-		omap_free_dma(dma_ch);
+		omap_free_dma(host->dma_ch);
+		host->dma_ch = -1;
+		up(&host->sem);
 	}
 	host->data = NULL;
 }
@@ -1034,21 +1011,28 @@ static inline void omap_hsmmc_reset_controller_fsm(struct omap_hsmmc_host *host,
 			__func__);
 }
 
-static void omap_hsmmc_do_irq(struct omap_hsmmc_host *host, int status)
+/*
+ * MMC controller IRQ handler
+ */
+static irqreturn_t omap_hsmmc_irq(int irq, void *dev_id)
 {
+	struct omap_hsmmc_host *host = dev_id;
 	struct mmc_data *data;
-	int end_cmd = 0, end_trans = 0;
-
-	if (!host->req_in_progress) {
-		do {
-			OMAP_HSMMC_WRITE(host->base, STAT, status);
-			/* Flush posted write */
-			status = OMAP_HSMMC_READ(host->base, STAT);
-		} while (status & INT_EN_MASK);
-		return;
+	int end_cmd = 0, end_trans = 0, status;
+
+	spin_lock(&host->irq_lock);
+
+	if (host->mrq == NULL) {
+		OMAP_HSMMC_WRITE(host->base, STAT,
+			OMAP_HSMMC_READ(host->base, STAT));
+		/* Flush posted write */
+		OMAP_HSMMC_READ(host->base, STAT);
+		spin_unlock(&host->irq_lock);
+		return IRQ_HANDLED;
 	}
 
 	data = host->data;
+	status = OMAP_HSMMC_READ(host->base, STAT);
 	dev_dbg(mmc_dev(host->mmc), "IRQ Status is %x\n", status);
 
 	if (status & ERR) {
@@ -1101,27 +1085,15 @@ static void omap_hsmmc_do_irq(struct omap_hsmmc_host *host, int status)
 	}
 
 	OMAP_HSMMC_WRITE(host->base, STAT, status);
+	/* Flush posted write */
+	OMAP_HSMMC_READ(host->base, STAT);
 
 	if (end_cmd || ((status & CC) && host->cmd))
 		omap_hsmmc_cmd_done(host, host->cmd);
 	if ((end_trans || (status & TC)) && host->mrq)
 		omap_hsmmc_xfer_done(host, data);
-}
-
-/*
- * MMC controller IRQ handler
- */
-static irqreturn_t omap_hsmmc_irq(int irq, void *dev_id)
-{
-	struct omap_hsmmc_host *host = dev_id;
-	int status;
 
-	status = OMAP_HSMMC_READ(host->base, STAT);
-	do {
-		omap_hsmmc_do_irq(host, status);
-		/* Flush posted write */
-		status = OMAP_HSMMC_READ(host->base, STAT);
-	} while (status & INT_EN_MASK);
+	spin_unlock(&host->irq_lock);
 
 	return IRQ_HANDLED;
 }
@@ -1316,11 +1288,9 @@ static void omap_hsmmc_config_dma_params(struct omap_hsmmc_host *host,
 /*
  * DMA call back function
  */
-static void omap_hsmmc_dma_cb(int lch, u16 ch_status, void *cb_data)
+static void omap_hsmmc_dma_cb(int lch, u16 ch_status, void *data)
 {
-	struct omap_hsmmc_host *host = cb_data;
-	struct mmc_data *data = host->mrq->data;
-	int dma_ch, req_in_progress;
+	struct omap_hsmmc_host *host = data;
 
 	if (!(ch_status & OMAP_DMA_BLOCK_IRQ)) {
 		dev_warn(mmc_dev(host->mmc), "unexpected dma status %x\n",
@@ -1328,38 +1298,24 @@ static void omap_hsmmc_dma_cb(int lch, u16 ch_status, void *cb_data)
 		return;
 	}
 
-	spin_lock(&host->irq_lock);
-	if (host->dma_ch < 0) {
-		spin_unlock(&host->irq_lock);
+	if (host->dma_ch < 0)
 		return;
-	}
 
 	host->dma_sg_idx++;
 	if (host->dma_sg_idx < host->dma_len) {
 		/* Fire up the next transfer. */
-		omap_hsmmc_config_dma_params(host, data,
-					   data->sg + host->dma_sg_idx);
-		spin_unlock(&host->irq_lock);
+		omap_hsmmc_config_dma_params(host, host->data,
+					   host->data->sg + host->dma_sg_idx);
 		return;
 	}
 
-	dma_unmap_sg(mmc_dev(host->mmc), data->sg, host->dma_len,
-		omap_hsmmc_get_dma_dir(host, data));
-
-	req_in_progress = host->req_in_progress;
-	dma_ch = host->dma_ch;
+	omap_free_dma(host->dma_ch);
 	host->dma_ch = -1;
-	spin_unlock(&host->irq_lock);
-
-	omap_free_dma(dma_ch);
-
-	/* If DMA has finished after TC, complete the request */
-	if (!req_in_progress) {
-		struct mmc_request *mrq = host->mrq;
-
-		host->mrq = NULL;
-		mmc_request_done(host->mmc, mrq);
-	}
+	/*
+	 * DMA Callback: run in interrupt context.
+	 * mutex_unlock will throw a kernel warning if used.
+	 */
+	up(&host->sem);
 }
 
 /*
@@ -1368,7 +1324,7 @@ static void omap_hsmmc_dma_cb(int lch, u16 ch_status, void *cb_data)
 static int omap_hsmmc_start_dma_transfer(struct omap_hsmmc_host *host,
 					struct mmc_request *req)
 {
-	int dma_ch = 0, ret = 0, i;
+	int dma_ch = 0, ret = 0, err = 1, i;
 	struct mmc_data *data = req->data;
 
 	/* Sanity check: all the SG entries must be aligned by block size. */
@@ -1385,7 +1341,23 @@ static int omap_hsmmc_start_dma_transfer(struct omap_hsmmc_host *host,
 		 */
 		return -EINVAL;
 
-	BUG_ON(host->dma_ch != -1);
+	/*
+	 * If for some reason the DMA transfer is still active,
+	 * we wait for timeout period and free the dma
+	 */
+	if (host->dma_ch != -1) {
+		set_current_state(TASK_UNINTERRUPTIBLE);
+		schedule_timeout(100);
+		if (down_trylock(&host->sem)) {
+			omap_free_dma(host->dma_ch);
+			host->dma_ch = -1;
+			up(&host->sem);
+			return err;
+		}
+	} else {
+		if (down_trylock(&host->sem))
+			return err;
+	}
 
 	ret = omap_request_dma(omap_hsmmc_get_dma_sync_dev(host, data),
 			       "MMC/SD", omap_hsmmc_dma_cb, host, &dma_ch);
@@ -1485,27 +1457,37 @@ static void omap_hsmmc_request(struct mmc_host *mmc, struct mmc_request *req)
 	struct omap_hsmmc_host *host = mmc_priv(mmc);
 	int err;
 
-	BUG_ON(host->req_in_progress);
-	BUG_ON(host->dma_ch != -1);
-	if (host->protect_card) {
-		if (host->reqs_blocked < 3) {
-			/*
-			 * Ensure the controller is left in a consistent
-			 * state by resetting the command and data state
-			 * machines.
-			 */
-			omap_hsmmc_reset_controller_fsm(host, SRD);
-			omap_hsmmc_reset_controller_fsm(host, SRC);
-			host->reqs_blocked += 1;
-		}
-		req->cmd->error = -EBADF;
-		if (req->data)
-			req->data->error = -EBADF;
-		req->cmd->retries = 0;
-		mmc_request_done(mmc, req);
-		return;
-	} else if (host->reqs_blocked)
-		host->reqs_blocked = 0;
+	/*
+	 * Prevent races with the interrupt handler because of unexpected
+	 * interrupts, but not if we are already in interrupt context i.e.
+	 * retries.
+	 */
+	if (!in_interrupt()) {
+		spin_lock_irqsave(&host->irq_lock, host->flags);
+		/*
+		 * Protect the card from I/O if there is a possibility
+		 * it can be removed.
+		 */
+		if (host->protect_card) {
+			if (host->reqs_blocked < 3) {
+				/*
+				 * Ensure the controller is left in a consistent
+				 * state by resetting the command and data state
+				 * machines.
+				 */
+				omap_hsmmc_reset_controller_fsm(host, SRD);
+				omap_hsmmc_reset_controller_fsm(host, SRC);
+				host->reqs_blocked += 1;
+			}
+			req->cmd->error = -EBADF;
+			if (req->data)
+				req->data->error = -EBADF;
+			spin_unlock_irqrestore(&host->irq_lock, host->flags);
+			mmc_request_done(mmc, req);
+			return;
+		} else if (host->reqs_blocked)
+			host->reqs_blocked = 0;
+	}
 	WARN_ON(host->mrq != NULL);
 	host->mrq = req;
 	err = omap_hsmmc_prepare_data(host, req);
@@ -1514,6 +1496,8 @@ static void omap_hsmmc_request(struct mmc_host *mmc, struct mmc_request *req)
 		if (req->data)
 			req->data->error = err;
 		host->mrq = NULL;
+		if (!in_interrupt())
+			spin_unlock_irqrestore(&host->irq_lock, host->flags);
 		mmc_request_done(mmc, req);
 		return;
 	}
@@ -2093,6 +2077,7 @@ static int __init omap_hsmmc_probe(struct platform_device *pdev)
 	mmc->f_min	= 400000;
 	mmc->f_max	= 52000000;
 
+	sema_init(&host->sem, 1);
 	spin_lock_init(&host->irq_lock);
 
 	host->iclk = clk_get(&pdev->dev, "ick");
@@ -2235,7 +2220,8 @@ static int __init omap_hsmmc_probe(struct platform_device *pdev)
 		pdata->resume = omap_hsmmc_resume_cdirq;
 	}
 
-	omap_hsmmc_disable_irq(host);
+	OMAP_HSMMC_WRITE(host->base, ISE, INT_EN_MASK);
+	OMAP_HSMMC_WRITE(host->base, IE, INT_EN_MASK);
 
 	mmc_host_lazy_disable(host->mmc);
 
@@ -2356,7 +2342,10 @@ static int omap_hsmmc_suspend(struct device *dev)
 		ret = mmc_suspend_host(host->mmc);
 		mmc_host_enable(host->mmc);
 		if (ret == 0) {
-			omap_hsmmc_disable_irq(host);
+			OMAP_HSMMC_WRITE(host->base, ISE, 0);
+			OMAP_HSMMC_WRITE(host->base, IE, 0);
+
+
 			OMAP_HSMMC_WRITE(host->base, HCTL,
 				OMAP_HSMMC_READ(host->base, HCTL) & ~SDBP);
 			mmc_host_disable(host->mmc);
-- 
1.6.6.1

