Adrian Hunter <adrian.hunter@xxxxxxxxx> wrote:
> From: Adrian Hunter <adrian.hunter@xxxxxxxxx>
> Date: Wed, 14 Apr 2010 16:26:45 +0300
> Subject: [PATCH] omap_hsmmc: improve interrupt synchronisation
>
> The following changes were needed:
> - do not use in_interrupt() because it will not work
> with threaded interrupts
>
> In addition, the following improvements were made:
> - ensure DMA is unmapped only after the final DMA interrupt
> - ensure a request is completed only after the final DMA interrupt
> - disable controller interrupts when a request is not in progress
> - remove the spin-lock protecting the start of a new request from
> an unexpected interrupt because the locking was complicated and
> a 'req_in_progress' flag suffices (since the spin-lock only defers
> the unexpected interrupts anyway)
> - remove the semaphore preventing DMA from being started while
> the previous DMA is still in progress - the other changes make that
> impossible, so it is now a BUG_ON condition
> - ensure the controller interrupt status is clear before exiting
> the interrupt handler
>
On OMAP4, the MMC and DMA interrupt lines could be routed to different CPUs
and the handlers could be executed simultaneously.
The req_in_progress variable would need spin lock protection in this case.
> In general, these changes make the code safer but do not fix any specific
> bugs so backporting is not necessary.
>
> Signed-off-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
> ---
> drivers/mmc/host/omap_hsmmc.c | 211
> ++++++++++++++++++-----------------------
> 1 files changed, 94 insertions(+), 117 deletions(-)
>
> diff --git a/drivers/mmc/host/omap_hsmmc.c b/drivers/mmc/host/omap_hsmmc.c
> index c0b5021..e58ca99 100644
> --- a/drivers/mmc/host/omap_hsmmc.c
> +++ b/drivers/mmc/host/omap_hsmmc.c
> @@ -157,11 +157,9 @@ 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;
> @@ -183,6 +181,7 @@ struct omap_hsmmc_host {
> int protect_card;
> int reqs_blocked;
> int use_reg;
> + int req_in_progress;
>
> struct omap_mmc_platform_data *pdata;
> };
> @@ -480,6 +479,27 @@ 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)
> +{
> + unsigned int irq_mask;
> +
> + if (host->use_dma)
> + irq_mask = INT_EN_MASK & ~(BRR_ENABLE | BWR_ENABLE);
> + else
> + irq_mask = INT_EN_MASK;
> +
> + 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
>
> /*
> @@ -548,9 +568,7 @@ static int omap_hsmmc_context_restore(struct
> omap_hsmmc_host *host)
> && time_before(jiffies, timeout))
> ;
>
> - 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);
> + omap_hsmmc_disable_irq(host);
>
> /* Do not initialize card-specific things if the power is off */
> if (host->power_mode == MMC_POWER_OFF)
> @@ -653,6 +671,8 @@ 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);
> @@ -718,17 +738,7 @@ omap_hsmmc_start_command(struct omap_hsmmc_host *host,
> struct mmc_command *cmd,
> mmc_hostname(host->mmc), cmd->opcode, cmd->arg);
> host->cmd = 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);
> + omap_hsmmc_enable_irq(host);
>
> host->response_busy = 0;
> if (cmd->flags & MMC_RSP_PRESENT) {
> @@ -762,13 +772,7 @@ omap_hsmmc_start_command(struct omap_hsmmc_host *host,
> struct mmc_command *cmd,
> if (host->use_dma)
> cmdreg |= DMA_EN;
>
> - /*
> - * 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);
> + host->req_in_progress = 1;
>
> OMAP_HSMMC_WRITE(host->base, ARG, cmd->arg);
> OMAP_HSMMC_WRITE(host->base, CMD, cmdreg);
> @@ -783,6 +787,17 @@ 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)
> +{
> + host->req_in_progress = 0;
> + omap_hsmmc_disable_irq(host);
> + /* Do not complete the request if DMA is still in progress */
> + if (mrq->data && host->use_dma && host->dma_ch != -1)
> + return;
> + host->mrq = NULL;
> + mmc_request_done(host->mmc, mrq);
> +}
> +
> /*
> * Notify the transfer complete to MMC core
> */
> @@ -799,25 +814,19 @@ omap_hsmmc_xfer_done(struct omap_hsmmc_host *host,
> struct mmc_data *data)
> return;
> }
>
> - host->mrq = NULL;
> - mmc_request_done(host->mmc, mrq);
> + omap_hsmmc_request_done(host, 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) {
> - host->mrq = NULL;
> - mmc_request_done(host->mmc, data->mrq);
> + omap_hsmmc_request_done(host, data->mrq);
> return;
> }
> omap_hsmmc_start_command(host, data->stop, NULL);
> @@ -843,10 +852,8 @@ 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) {
> - host->mrq = NULL;
> - mmc_request_done(host->mmc, cmd->mrq);
> - }
> + if ((host->data == NULL && !host->response_busy) || cmd->error)
> + omap_hsmmc_request_done(host, cmd->mrq);
> }
>
> /*
> @@ -861,7 +868,6 @@ static void omap_hsmmc_dma_cleanup(struct
> omap_hsmmc_host *host, int errno)
> omap_hsmmc_get_dma_dir(host, host->data));
> omap_free_dma(host->dma_ch);
> host->dma_ch = -1;
> - up(&host->sem);
> }
> host->data = NULL;
> }
> @@ -932,19 +938,18 @@ static irqreturn_t omap_hsmmc_irq(int irq, void
> *dev_id)
> struct mmc_data *data;
> 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);
> + status = OMAP_HSMMC_READ(host->base, STAT);
> +again:
> + 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 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) {
> @@ -997,15 +1002,16 @@ static irqreturn_t omap_hsmmc_irq(int irq, void
> *dev_id)
> }
>
> 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);
>
> - spin_unlock(&host->irq_lock);
> + /* Flush posted write */
> + status = OMAP_HSMMC_READ(host->base, STAT);
> + if (status & INT_EN_MASK)
> + goto again;
Hmm.. Perhaps a matter of style, but it's better to avoid using labelled jumps
backwards, and use labels only for error handling.
If clearing all interrrupts is the intention, maybe the whole
IRQ handler function should have a loop like this ?
while ( OMAP_HSMMC_READ(host->base, STAT) && INT_EN_MASK) {
...
....
/* Flush posted write */
}
>
> return IRQ_HANDLED;
> }
> @@ -1205,9 +1211,10 @@ 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 *data)
> +static void omap_hsmmc_dma_cb(int lch, u16 ch_status, void *cb_data)
> {
> - struct omap_hsmmc_host *host = data;
> + struct omap_hsmmc_host *host = cb_data;
> + struct mmc_data *data = host->mrq->data;
>
> if (ch_status & OMAP2_DMA_MISALIGNED_ERR_IRQ)
> dev_dbg(mmc_dev(host->mmc), "MISALIGNED_ADRS_ERR\n");
> @@ -1218,18 +1225,23 @@ static void omap_hsmmc_dma_cb(int lch, u16
> ch_status, void *data)
> host->dma_sg_idx++;
> if (host->dma_sg_idx < host->dma_len) {
> /* Fire up the next transfer. */
> - omap_hsmmc_config_dma_params(host, host->data,
> - host->data->sg +
> host->dma_sg_idx);
> + omap_hsmmc_config_dma_params(host, data,
> + data->sg + host->dma_sg_idx);
> return;
> }
>
> omap_free_dma(host->dma_ch);
> + dma_unmap_sg(mmc_dev(host->mmc), data->sg, host->dma_len,
> + omap_hsmmc_get_dma_dir(host, data));
> host->dma_ch = -1;
Is it possible to use omap_hsmmc_dma_cleanup(host, 0) here?
It makes all the clean up points to be consistent.
> - /*
> - * DMA Callback: run in interrupt context.
> - * mutex_unlock will throw a kernel warning if used.
> - */
> - up(&host->sem);
> +
> + /* If DMA has finished after TC, complete the request */
> + if (!host->req_in_progress) {
> + struct mmc_request *mrq = host->mrq;
> +
> + host->mrq = NULL;
> + mmc_request_done(host->mmc, mrq);
> + }
> }
>
> /*
> @@ -1238,7 +1250,7 @@ static void omap_hsmmc_dma_cb(int lch, u16 ch_status,
> void *data)
> static int omap_hsmmc_start_dma_transfer(struct omap_hsmmc_host *host,
> struct mmc_request *req)
> {
> - int dma_ch = 0, ret = 0, err = 1, i;
> + int dma_ch = 0, ret = 0, i;
> struct mmc_data *data = req->data;
>
> /* Sanity check: all the SG entries must be aligned by block size. */
> @@ -1255,23 +1267,7 @@ static int omap_hsmmc_start_dma_transfer(struct
> omap_hsmmc_host *host,
> */
> return -EINVAL;
>
> - /*
> - * 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;
> - }
> + BUG_ON(host->dma_ch != -1);
>
> ret = omap_request_dma(omap_hsmmc_get_dma_sync_dev(host, data),
> "MMC/SD", omap_hsmmc_dma_cb, host, &dma_ch);
> @@ -1371,37 +1367,27 @@ static void omap_hsmmc_request(struct mmc_host *mmc,
> struct mmc_request *req)
> struct omap_hsmmc_host *host = mmc_priv(mmc);
> int err;
>
> - /*
> - * 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;
> - }
> + 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;
> WARN_ON(host->mrq != NULL);
> host->mrq = req;
> err = omap_hsmmc_prepare_data(host, req);
> @@ -1410,8 +1396,6 @@ 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;
> }
> @@ -1980,9 +1964,6 @@ 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");
> if (IS_ERR(host->iclk)) {
> ret = PTR_ERR(host->iclk);
> @@ -2126,8 +2107,7 @@ static int __init omap_hsmmc_probe(struct
> platform_device *pdev)
> }
> }
>
> - OMAP_HSMMC_WRITE(host->base, ISE, INT_EN_MASK);
> - OMAP_HSMMC_WRITE(host->base, IE, INT_EN_MASK);
> + omap_hsmmc_disable_irq(host);
>
> mmc_host_lazy_disable(host->mmc);
>
> @@ -2247,10 +2227,7 @@ static int omap_hsmmc_suspend(struct platform_device
> *pdev, pm_message_t state)
> mmc_host_enable(host->mmc);
> ret = mmc_suspend_host(host->mmc, state);
> if (ret == 0) {
> - OMAP_HSMMC_WRITE(host->base, ISE, 0);
> - OMAP_HSMMC_WRITE(host->base, IE, 0);
> -
> -
> + omap_hsmmc_disable_irq(host);
> OMAP_HSMMC_WRITE(host->base, HCTL,
> OMAP_HSMMC_READ(host->base, HCTL) & ~SDBP);
> mmc_host_disable(host->mmc);
> --
> 1.6.3.3
> --
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