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Commit 0807a9b5 authored by Jarkko Lavinen's avatar Jarkko Lavinen Committed by Pierre Ossman
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MMC: OMAP: Lazy clock shutdown 



MMCA spec says the mmc clock should be kept running for at least
8 cycles after the last RW request. Ensure this with lazy clock
disable after a request, or with an explicit delay before
switching a slot.

Signed-off-by: default avatarJarkko Lavinen <jarkko.lavinen@nokia.com>
Signed-off-by: default avatarPierre Ossman <drzeus@drzeus.cx>
parent 0fb4723d

drivers/mmc/host/omap.c

+75 −14
Original line number Diff line number Diff line
@@ -161,9 +161,38 @@ struct mmc_omap_host { 
	wait_queue_head_t       slot_wq;

	int                     nr_slots;



	struct timer_list       clk_timer;

	spinlock_t		clk_lock;     /* for changing enabled state */

	unsigned int            fclk_enabled:1;



	struct omap_mmc_platform_data *pdata;

};



void mmc_omap_fclk_offdelay(struct mmc_omap_slot *slot)

{

	unsigned long tick_ns;



	if (slot != NULL && slot->host->fclk_enabled && slot->fclk_freq > 0) {

		tick_ns = (1000000000 + slot->fclk_freq - 1) / slot->fclk_freq;

		ndelay(8 * tick_ns);

	}

}



void mmc_omap_fclk_enable(struct mmc_omap_host *host, unsigned int enable)

{

	unsigned long flags;



	spin_lock_irqsave(&host->clk_lock, flags);

	if (host->fclk_enabled != enable) {

		host->fclk_enabled = enable;

		if (enable)

			clk_enable(host->fclk);

		else

			clk_disable(host->fclk);

	}

	spin_unlock_irqrestore(&host->clk_lock, flags);

}



static void mmc_omap_select_slot(struct mmc_omap_slot *slot, int claimed)

{

	struct mmc_omap_host *host = slot->host;
@@ -180,32 +209,49 @@ static void mmc_omap_select_slot(struct mmc_omap_slot *slot, int claimed) 
	host->mmc = slot->mmc;

	spin_unlock_irqrestore(&host->slot_lock, flags);

no_claim:

	clk_enable(host->fclk);

	del_timer(&host->clk_timer);

	if (host->current_slot != slot || !claimed)

		mmc_omap_fclk_offdelay(host->current_slot);



	if (host->current_slot != slot) {

		OMAP_MMC_WRITE(host, CON, slot->saved_con & 0xFC00);

		if (host->pdata->switch_slot != NULL)

			host->pdata->switch_slot(mmc_dev(slot->mmc), slot->id);

		host->current_slot = slot;

	}



	if (claimed) {

		mmc_omap_fclk_enable(host, 1);



		/* Doing the dummy read here seems to work around some bug

		 * at least in OMAP24xx silicon where the command would not

		 * start after writing the CMD register. Sigh. */

		OMAP_MMC_READ(host, CON);



		OMAP_MMC_WRITE(host, CON, slot->saved_con);

	} else

		mmc_omap_fclk_enable(host, 0);

}



static void mmc_omap_start_request(struct mmc_omap_host *host,

				   struct mmc_request *req);



static void mmc_omap_release_slot(struct mmc_omap_slot *slot)

static void mmc_omap_release_slot(struct mmc_omap_slot *slot, int clk_enabled)

{

	struct mmc_omap_host *host = slot->host;

	unsigned long flags;

	int i;



	BUG_ON(slot == NULL || host->mmc == NULL);

	clk_disable(host->fclk);



	if (clk_enabled)

		/* Keeps clock running for at least 8 cycles on valid freq */

		mod_timer(&host->clk_timer, jiffies  + HZ/10);

	else {

		del_timer(&host->clk_timer);

		mmc_omap_fclk_offdelay(slot);

		mmc_omap_fclk_enable(host, 0);

	}



	spin_lock_irqsave(&host->slot_lock, flags);

	/* Check for any pending requests */
@@ -373,7 +419,7 @@ mmc_omap_xfer_done(struct mmc_omap_host *host, struct mmc_data *data) 


		host->mrq = NULL;

		mmc = host->mmc;

		mmc_omap_release_slot(host->current_slot);

		mmc_omap_release_slot(host->current_slot, 1);

		mmc_request_done(mmc, data->mrq);

		return;

	}
@@ -507,7 +553,7 @@ mmc_omap_cmd_done(struct mmc_omap_host *host, struct mmc_command *cmd) 
			mmc_omap_abort_xfer(host, host->data);

		host->mrq = NULL;

		mmc = host->mmc;

		mmc_omap_release_slot(host->current_slot);

		mmc_omap_release_slot(host->current_slot, 1);

		mmc_request_done(mmc, cmd->mrq);

	}

}
@@ -538,7 +584,7 @@ static void mmc_omap_abort_command(struct work_struct *work) 


		host->mrq = NULL;

		mmc = host->mmc;

		mmc_omap_release_slot(host->current_slot);

		mmc_omap_release_slot(host->current_slot, 1);

		mmc_request_done(mmc, cmd->mrq);

	} else

		mmc_omap_cmd_done(host, host->cmd);
@@ -576,6 +622,14 @@ mmc_omap_sg_to_buf(struct mmc_omap_host *host) 
		host->buffer_bytes_left = host->total_bytes_left;

}



static void

mmc_omap_clk_timer(unsigned long data)

{

	struct mmc_omap_host *host = (struct mmc_omap_host *) data;



	mmc_omap_fclk_enable(host, 0);

}



/* PIO only */

static void

mmc_omap_xfer_data(struct mmc_omap_host *host, int write)
@@ -1149,14 +1203,16 @@ static void mmc_omap_set_ios(struct mmc_host *mmc, struct mmc_ios *ios) 
	struct mmc_omap_slot *slot = mmc_priv(mmc);

	struct mmc_omap_host *host = slot->host;

	int i, dsor;



	dsor = mmc_omap_calc_divisor(mmc, ios);

	int clk_enabled;



	mmc_omap_select_slot(slot, 0);



	dsor = mmc_omap_calc_divisor(mmc, ios);



	if (ios->vdd != slot->vdd)

		slot->vdd = ios->vdd;



	clk_enabled = 0;

	switch (ios->power_mode) {

	case MMC_POWER_OFF:

		mmc_omap_set_power(slot, 0, ios->vdd);
@@ -1166,6 +1222,8 @@ static void mmc_omap_set_ios(struct mmc_host *mmc, struct mmc_ios *ios) 
		mmc_omap_set_power(slot, 1, ios->vdd);

		goto exit;

	case MMC_POWER_ON:

		mmc_omap_fclk_enable(host, 1);

		clk_enabled = 1;

		dsor |= 1 << 11;

		break;

	}
@@ -1194,7 +1252,7 @@ static void mmc_omap_set_ios(struct mmc_host *mmc, struct mmc_ios *ios) 
	}



exit:

	mmc_omap_release_slot(slot);

	mmc_omap_release_slot(slot, clk_enabled);

}



static const struct mmc_host_ops mmc_omap_ops = {
@@ -1335,6 +1393,9 @@ static int __init mmc_omap_probe(struct platform_device *pdev) 
	setup_timer(&host->cmd_abort_timer, mmc_omap_cmd_timer,

		    (unsigned long) host);



	spin_lock_init(&host->clk_lock);

	setup_timer(&host->clk_timer, mmc_omap_clk_timer, (unsigned long) host);



	spin_lock_init(&host->dma_lock);

	setup_timer(&host->dma_timer, mmc_omap_dma_timer, (unsigned long) host);

	spin_lock_init(&host->slot_lock);