openwrt/target/linux/brcm2708/patches-4.4/0223-Revert-bcm2835-sdhost-Precalc-divisors-and-overclock.patch

From cc8d551542116bd779ee2ceb63746324bc3732ed Mon Sep 17 00:00:00 2001
From: Phil Elwell <phil@raspberrypi.org>
Date: Mon, 4 Apr 2016 12:35:32 +0100
Subject: [PATCH] Revert "bcm2835-sdhost: Precalc divisors and overclocks"

This reverts commit 20260462773366a5734e5268dae0a4c179a21a2d.
---
 drivers/mmc/host/bcm2835-sdhost.c | 152 ++++++++++++++++----------------------
 1 file changed, 64 insertions(+), 88 deletions(-)

--- a/drivers/mmc/host/bcm2835-sdhost.c
+++ b/drivers/mmc/host/bcm2835-sdhost.c
@@ -154,15 +154,12 @@ struct bcm2835_host {
 	u32			pio_timeout;	/* In jiffies */
 
 	int			clock;		/* Current clock speed */
-	int			clocks[2];
 
 	bool			slow_card;	/* Force 11-bit divisor */
 
 	unsigned int		max_clk;	/* Max src clock freq */
-	unsigned int		src_clks[2];	/* Min/max src clock freqs */
-	unsigned int		cur_clk_idx;	/* Index of current clock */
-	unsigned int		next_clk_idx;	/* Next clock index */
-	unsigned int		cdivs[2];
+	unsigned int		min_clk;	/* Min src clock freq */
+	unsigned int		cur_clk;	/* Current src clock freq */
 
 	struct tasklet_struct	finish_tasklet;	/* Tasklet structures */
 
@@ -216,7 +213,7 @@ struct bcm2835_host {
 	u32				delay_after_stop; /* minimum time between stop and subsequent data transfer */
 	u32				delay_after_this_stop; /* minimum time between this stop and subsequent data transfer */
 	u32				overclock_50;	/* frequency to use when 50MHz is requested (in MHz) */
-	u32				prev_overclock_50;
+	u32				overclock;	/* Current frequency if overclocked, else zero */
 	u32				pio_limit;	/* Maximum block count for PIO (0 = always DMA) */
 
 	u32				sectors;	/* Cached card size in sectors */
@@ -1512,35 +1509,10 @@ static irqreturn_t bcm2835_sdhost_irq(in
 	return result;
 }
 
-static void bcm2835_sdhost_select_clock(struct bcm2835_host *host, int idx)
-{
-	unsigned int clock = host->clocks[idx];
-	unsigned int cdiv = host->cdivs[idx];
-
-	host->mmc->actual_clock = clock;
-	host->ns_per_fifo_word = (1000000000/clock) *
-		((host->mmc->caps & MMC_CAP_4_BIT_DATA) ? 8 : 32);
-
-	host->cdiv = cdiv;
-	bcm2835_sdhost_write(host, host->cdiv, SDCDIV);
-
-	/* Set the timeout to 500ms */
-	bcm2835_sdhost_write(host, clock/2, SDTOUT);
-
-	host->cur_clk_idx = host->next_clk_idx = idx;
-
-	if (host->debug)
-		pr_info("%s: clock=%d -> src_clk=%d, cdiv=%x (actual %d)\n",
-			mmc_hostname(host->mmc), host->clock,
-			host->src_clks[idx], host->cdiv,
-			host->mmc->actual_clock);
-}
-
 void bcm2835_sdhost_set_clock(struct bcm2835_host *host)
 {
 	int div = 0; /* Initialized for compiler warning */
 	unsigned int clock = host->clock;
-	int clk_idx;
 
 	if (host->debug)
 		pr_info("%s: set_clock(%d)\n", mmc_hostname(host->mmc), clock);
@@ -1581,45 +1553,53 @@ void bcm2835_sdhost_set_clock(struct bcm
 	    return;
 	}
 
-	/* Calculate the clock divisors */
-	for (clk_idx = 0; clk_idx <= host->variable_clock; clk_idx++)
-	{
-		unsigned int cur_clk = host->src_clks[clk_idx];
-		unsigned int actual_clock;
+	div = host->cur_clk / clock;
+	if (div < 2)
+		div = 2;
+	if ((host->cur_clk / div) > clock)
+		div++;
+	div -= 2;
+
+	if (div > SDCDIV_MAX_CDIV)
+	    div = SDCDIV_MAX_CDIV;
+
+	clock = host->cur_clk / (div + 2);
+	host->mmc->actual_clock = clock;
+
+	/* Calibrate some delays */
+
+	host->ns_per_fifo_word = (1000000000/clock) *
+		((host->mmc->caps & MMC_CAP_4_BIT_DATA) ? 8 : 32);
 
-		div = cur_clk / clock;
-		if (div < 2)
-			div = 2;
-		if ((cur_clk / div) > clock)
-			div++;
-		div -= 2;
-
-		if (div > SDCDIV_MAX_CDIV)
-			div = SDCDIV_MAX_CDIV;
-		actual_clock = cur_clk / (div + 2);
-
-		host->cdivs[clk_idx] = div;
-		host->clocks[clk_idx] = actual_clock;
-
-		if (host->overclock_50 != host->prev_overclock_50) {
-			const char *clk_name = "";
-			if (host->variable_clock)
-				clk_name = clk_idx ? " (turbo)" : " (normal)";
-			if (actual_clock > host->clock)
-				pr_info("%s: overclocking to %dHz%s\n",
-					mmc_hostname(host->mmc),
-					actual_clock, clk_name);
-			else if ((host->overclock_50 < 50) && (clk_idx == 0))
-				pr_info("%s: cancelling overclock%s\n",
-					mmc_hostname(host->mmc),
-					host->variable_clock ? "s" : "");
+	if (clock > host->clock) {
+		/* Save the closest value, to make it easier
+		   to reduce in the event of error */
+		host->overclock_50 = (clock/MHZ);
+
+		if (clock != host->overclock) {
+			pr_warn("%s: overclocking to %dHz\n",
+				mmc_hostname(host->mmc), clock);
+			host->overclock = clock;
 		}
 	}
+	else if (host->overclock)
+	{
+		host->overclock = 0;
+		if (clock == 50 * MHZ)
+			pr_warn("%s: cancelling overclock\n",
+				mmc_hostname(host->mmc));
+	}
 
-	if (host->clock == 50*MHZ)
-		host->prev_overclock_50 = host->overclock_50;
+	host->cdiv = div;
+	bcm2835_sdhost_write(host, host->cdiv, SDCDIV);
 
-	bcm2835_sdhost_select_clock(host, host->cur_clk_idx);
+	/* Set the timeout to 500ms */
+	bcm2835_sdhost_write(host, host->mmc->actual_clock/2, SDTOUT);
+
+	if (host->debug)
+		pr_info("%s: clock=%d -> cur_clk=%d, cdiv=%x (actual clock %d)\n",
+			mmc_hostname(host->mmc), host->clock,
+			host->cur_clk, host->cdiv, host->mmc->actual_clock);
 }
 
 static void bcm2835_sdhost_request(struct mmc_host *mmc, struct mmc_request *mrq)
@@ -1677,9 +1657,6 @@ static void bcm2835_sdhost_request(struc
 
 	spin_lock_irqsave(&host->lock, flags);
 
-	if (host->next_clk_idx != host->cur_clk_idx)
-		bcm2835_sdhost_select_clock(host, host->next_clk_idx);
-
 	WARN_ON(host->mrq != NULL);
 	host->mrq = mrq;
 
@@ -1742,7 +1719,11 @@ static int bcm2835_sdhost_cpufreq_callba
 				return NOTIFY_BAD;
 			break;
 		case CPUFREQ_POSTCHANGE:
-			host->next_clk_idx = (freq->new > freq->old);
+			if (freq->new > freq->old)
+				host->cur_clk = host->max_clk;
+			else
+				host->cur_clk = host->min_clk;
+			bcm2835_sdhost_set_clock(host);
 			up(&host->cpufreq_semaphore);
 			break;
 		default:
@@ -1782,11 +1763,8 @@ static void bcm2835_sdhost_set_ios(struc
 			ios->clock, ios->power_mode, ios->bus_width,
 			ios->timing, ios->signal_voltage, ios->drv_type);
 
-	if (ios->clock && (host->cur_clk_idx == -1)) {
-		unsigned int cur_clk =
-			get_core_clock(RPI_FIRMWARE_GET_CLOCK_RATE);
-		host->cur_clk_idx = (cur_clk == host->src_clks[0]) ? 0 : 1;
-	}
+	if (ios->clock && !host->cur_clk)
+		host->cur_clk = get_core_clock(RPI_FIRMWARE_GET_CLOCK_RATE);
 
 	spin_lock_irqsave(&host->lock, flags);
 
@@ -1876,12 +1854,11 @@ static void bcm2835_sdhost_tasklet_finis
 
 	/* Drop the overclock after any data corruption, or after any
 	   error overclocked */
-	if (host->clock > 50*MHZ) {
+	if (host->overclock) {
 		if ((mrq->cmd && mrq->cmd->error) ||
 		    (mrq->data && mrq->data->error) ||
 		    (mrq->stop && mrq->stop->error)) {
-			host->overclock_50 = (host->clock/MHZ) - 1;
-
+			host->overclock_50--;
 			pr_warn("%s: reducing overclock due to errors\n",
 				mmc_hostname(host->mmc));
 			bcm2835_sdhost_set_clock(host);
@@ -2045,7 +2022,7 @@ static int bcm2835_sdhost_probe(struct p
 	struct bcm2835_host *host;
 	struct mmc_host *mmc;
 	const __be32 *addr;
-	unsigned int max_clk, min_clk;
+	unsigned int max_clk;
 	int ret;
 
 	pr_debug("bcm2835_sdhost_probe\n");
@@ -2151,8 +2128,12 @@ static int bcm2835_sdhost_probe(struct p
 	else
 		mmc->caps |= MMC_CAP_4_BIT_DATA;
 
+	ret = bcm2835_sdhost_add_host(host);
+	if (ret)
+		goto err;
+
 	/* Query the core clock frequencies */
-	min_clk = get_core_clock(RPI_FIRMWARE_GET_MIN_CLOCK_RATE);
+	host->min_clk = get_core_clock(RPI_FIRMWARE_GET_MIN_CLOCK_RATE);
 	max_clk = get_core_clock(RPI_FIRMWARE_GET_MAX_CLOCK_RATE);
 	if (max_clk != host->max_clk) {
 		pr_warn("%s: Expected max clock %d, found %d\n",
@@ -2160,24 +2141,19 @@ static int bcm2835_sdhost_probe(struct p
 		host->max_clk = max_clk;
 	}
 
-	host->src_clks[0] = min_clk;
-	host->cur_clk_idx = -1;
-	if (max_clk != min_clk) {
-		host->src_clks[1] = max_clk;
+	if (host->min_clk != host->max_clk) {
 		host->cpufreq_nb.notifier_call =
 			bcm2835_sdhost_cpufreq_callback;
 		sema_init(&host->cpufreq_semaphore, 1);
 		cpufreq_register_notifier(&host->cpufreq_nb,
 					  CPUFREQ_TRANSITION_NOTIFIER);
 		host->variable_clock = 1;
+		host->cur_clk = 0; /* Get this later */
 	} else {
 		host->variable_clock = 0;
+		host->cur_clk = host->max_clk;
 	}
 
-	ret = bcm2835_sdhost_add_host(host);
-	if (ret)
-		goto err;
-
 	platform_set_drvdata(pdev, host);
 
 	pr_debug("bcm2835_sdhost_probe -> OK\n");