diff options
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/dma/amba-pl08x.c | 268 |
1 files changed, 112 insertions, 156 deletions
diff --git a/drivers/dma/amba-pl08x.c b/drivers/dma/amba-pl08x.c index 30b6921f094f..bbae30ceb8fb 100644 --- a/drivers/dma/amba-pl08x.c +++ b/drivers/dma/amba-pl08x.c @@ -210,8 +210,6 @@ enum pl08x_dma_chan_state { * struct pl08x_dma_chan - this structure wraps a DMA ENGINE channel * @chan: wrappped abstract channel * @phychan: the physical channel utilized by this channel, if there is one - * @phychan_hold: if non-zero, hold on to the physical channel even if we - * have no pending entries * @tasklet: tasklet scheduled by the IRQ to handle actual work etc * @name: name of channel * @cd: channel platform data @@ -230,7 +228,6 @@ enum pl08x_dma_chan_state { struct pl08x_dma_chan { struct dma_chan chan; struct pl08x_phy_chan *phychan; - int phychan_hold; struct tasklet_struct tasklet; const char *name; const struct pl08x_channel_data *cd; @@ -587,19 +584,111 @@ pl08x_get_phy_channel(struct pl08x_driver_data *pl08x, return ch; } +/* Mark the physical channel as free. Note, this write is atomic. */ static inline void pl08x_put_phy_channel(struct pl08x_driver_data *pl08x, struct pl08x_phy_chan *ch) { - unsigned long flags; + ch->serving = NULL; +} - spin_lock_irqsave(&ch->lock, flags); +/* + * Try to allocate a physical channel. When successful, assign it to + * this virtual channel, and initiate the next descriptor. The + * virtual channel lock must be held at this point. + */ +static void pl08x_phy_alloc_and_start(struct pl08x_dma_chan *plchan) +{ + struct pl08x_driver_data *pl08x = plchan->host; + struct pl08x_phy_chan *ch; - /* Stop the channel and clear its interrupts */ - pl08x_terminate_phy_chan(pl08x, ch); + ch = pl08x_get_phy_channel(pl08x, plchan); + if (!ch) { + dev_dbg(&pl08x->adev->dev, "no physical channel available for xfer on %s\n", plchan->name); + plchan->state = PL08X_CHAN_WAITING; + return; + } - /* Mark it as free */ - ch->serving = NULL; - spin_unlock_irqrestore(&ch->lock, flags); + dev_dbg(&pl08x->adev->dev, "allocated physical channel %d for xfer on %s\n", + ch->id, plchan->name); + + plchan->phychan = ch; + plchan->state = PL08X_CHAN_RUNNING; + pl08x_start_next_txd(plchan); +} + +static void pl08x_phy_reassign_start(struct pl08x_phy_chan *ch, + struct pl08x_dma_chan *plchan) +{ + struct pl08x_driver_data *pl08x = plchan->host; + + dev_dbg(&pl08x->adev->dev, "reassigned physical channel %d for xfer on %s\n", + ch->id, plchan->name); + + /* + * We do this without taking the lock; we're really only concerned + * about whether this pointer is NULL or not, and we're guaranteed + * that this will only be called when it _already_ is non-NULL. + */ + ch->serving = plchan; + plchan->phychan = ch; + plchan->state = PL08X_CHAN_RUNNING; + pl08x_start_next_txd(plchan); +} + +/* + * Free a physical DMA channel, potentially reallocating it to another + * virtual channel if we have any pending. + */ +static void pl08x_phy_free(struct pl08x_dma_chan *plchan) +{ + struct pl08x_driver_data *pl08x = plchan->host; + struct pl08x_dma_chan *p, *next; + + retry: + next = NULL; + + /* Find a waiting virtual channel for the next transfer. */ + list_for_each_entry(p, &pl08x->memcpy.channels, chan.device_node) + if (p->state == PL08X_CHAN_WAITING) { + next = p; + break; + } + + if (!next) { + list_for_each_entry(p, &pl08x->slave.channels, chan.device_node) + if (p->state == PL08X_CHAN_WAITING) { + next = p; + break; + } + } + + /* Ensure that the physical channel is stopped */ + pl08x_terminate_phy_chan(pl08x, plchan->phychan); + + if (next) { + bool success; + + /* + * Eww. We know this isn't going to deadlock + * but lockdep probably doesn't. + */ + spin_lock(&next->lock); + /* Re-check the state now that we have the lock */ + success = next->state == PL08X_CHAN_WAITING; + if (success) + pl08x_phy_reassign_start(plchan->phychan, next); + spin_unlock(&next->lock); + + /* If the state changed, try to find another channel */ + if (!success) + goto retry; + } else { + /* No more jobs, so free up the physical channel */ + pl08x_put_phy_channel(pl08x, plchan->phychan); + } + + plchan->phychan = NULL; + plchan->state = PL08X_CHAN_IDLE; } /* @@ -1028,45 +1117,6 @@ static void pl08x_free_chan_resources(struct dma_chan *chan) { } -/* - * This should be called with the channel plchan->lock held - */ -static int prep_phy_channel(struct pl08x_dma_chan *plchan) -{ - struct pl08x_driver_data *pl08x = plchan->host; - struct pl08x_phy_chan *ch; - - /* Check if we already have a channel */ - if (plchan->phychan) { - ch = plchan->phychan; - goto got_channel; - } - - ch = pl08x_get_phy_channel(pl08x, plchan); - if (!ch) { - /* No physical channel available, cope with it */ - dev_dbg(&pl08x->adev->dev, "no physical channel available for xfer on %s\n", plchan->name); - return -EBUSY; - } - - plchan->phychan = ch; - dev_dbg(&pl08x->adev->dev, "allocated physical channel %d for xfer on %s\n", - ch->id, plchan->name); - -got_channel: - plchan->phychan_hold++; - - return 0; -} - -static void release_phy_channel(struct pl08x_dma_chan *plchan) -{ - struct pl08x_driver_data *pl08x = plchan->host; - - pl08x_put_phy_channel(pl08x, plchan->phychan); - plchan->phychan = NULL; -} - static dma_cookie_t pl08x_tx_submit(struct dma_async_tx_descriptor *tx) { struct pl08x_dma_chan *plchan = to_pl08x_chan(tx->chan); @@ -1079,19 +1129,6 @@ static dma_cookie_t pl08x_tx_submit(struct dma_async_tx_descriptor *tx) /* Put this onto the pending list */ list_add_tail(&txd->node, &plchan->pend_list); - - /* - * If there was no physical channel available for this memcpy, - * stack the request up and indicate that the channel is waiting - * for a free physical channel. - */ - if (!plchan->slave && !plchan->phychan) { - /* Do this memcpy whenever there is a channel ready */ - plchan->state = PL08X_CHAN_WAITING; - } else { - plchan->phychan_hold--; - } - spin_unlock_irqrestore(&plchan->lock, flags); return cookie; @@ -1282,19 +1319,10 @@ static void pl08x_issue_pending(struct dma_chan *chan) spin_lock_irqsave(&plchan->lock, flags); list_splice_tail_init(&plchan->pend_list, &plchan->issued_list); - - /* Something is already active, or we're waiting for a channel... */ - if (plchan->at || plchan->state == PL08X_CHAN_WAITING) { - spin_unlock_irqrestore(&plchan->lock, flags); - return; - } - - /* Take the first element in the queue and execute it */ if (!list_empty(&plchan->issued_list)) { - plchan->state = PL08X_CHAN_RUNNING; - pl08x_start_next_txd(plchan); + if (!plchan->phychan && plchan->state != PL08X_CHAN_WAITING) + pl08x_phy_alloc_and_start(plchan); } - spin_unlock_irqrestore(&plchan->lock, flags); } @@ -1302,48 +1330,18 @@ static int pl08x_prep_channel_resources(struct pl08x_dma_chan *plchan, struct pl08x_txd *txd) { struct pl08x_driver_data *pl08x = plchan->host; - unsigned long flags; - int num_llis, ret; + int num_llis; num_llis = pl08x_fill_llis_for_desc(pl08x, txd); if (!num_llis) { + unsigned long flags; + spin_lock_irqsave(&plchan->lock, flags); pl08x_free_txd(pl08x, txd); spin_unlock_irqrestore(&plchan->lock, flags); + return -EINVAL; } - - spin_lock_irqsave(&plchan->lock, flags); - - /* - * See if we already have a physical channel allocated, - * else this is the time to try to get one. - */ - ret = prep_phy_channel(plchan); - if (ret) { - /* - * No physical channel was available. - * - * memcpy transfers can be sorted out at submission time. - */ - if (plchan->slave) { - pl08x_free_txd_list(pl08x, plchan); - pl08x_free_txd(pl08x, txd); - spin_unlock_irqrestore(&plchan->lock, flags); - return -EBUSY; - } - } else - /* - * Else we're all set, paused and ready to roll, status - * will switch to PL08X_CHAN_RUNNING when we call - * issue_pending(). If there is something running on the - * channel already we don't change its state. - */ - if (plchan->state == PL08X_CHAN_IDLE) - plchan->state = PL08X_CHAN_PAUSED; - - spin_unlock_irqrestore(&plchan->lock, flags); - return 0; } @@ -1563,14 +1561,11 @@ static int pl08x_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd, plchan->state = PL08X_CHAN_IDLE; if (plchan->phychan) { - pl08x_terminate_phy_chan(pl08x, plchan->phychan); - /* * Mark physical channel as free and free any slave * signal */ - release_phy_channel(plchan); - plchan->phychan_hold = 0; + pl08x_phy_free(plchan); } /* Dequeue jobs and free LLIs */ if (plchan->at) { @@ -1670,50 +1665,6 @@ static void pl08x_tasklet(unsigned long data) spin_lock_irqsave(&plchan->lock, flags); list_splice_tail_init(&plchan->done_list, &head); - - if (plchan->at || !list_empty(&plchan->pend_list) || plchan->phychan_hold) { - /* - * This channel is still in use - we have a new txd being - * prepared and will soon be queued. Don't give up the - * physical channel. - */ - } else { - struct pl08x_dma_chan *waiting = NULL; - - /* - * No more jobs, so free up the physical channel - */ - release_phy_channel(plchan); - plchan->state = PL08X_CHAN_IDLE; - - /* - * And NOW before anyone else can grab that free:d up - * physical channel, see if there is some memcpy pending - * that seriously needs to start because of being stacked - * up while we were choking the physical channels with data. - */ - list_for_each_entry(waiting, &pl08x->memcpy.channels, - chan.device_node) { - if (waiting->state == PL08X_CHAN_WAITING) { - int ret; - - /* This should REALLY not fail now */ - ret = prep_phy_channel(waiting); - BUG_ON(ret); - waiting->phychan_hold--; - waiting->state = PL08X_CHAN_RUNNING; - /* - * Eww. We know this isn't going to deadlock - * but lockdep probably doens't. - */ - spin_lock(&waiting->lock); - pl08x_start_next_txd(waiting); - spin_unlock(&waiting->lock); - break; - } - } - } - spin_unlock_irqrestore(&plchan->lock, flags); while (!list_empty(&head)) { @@ -1784,9 +1735,14 @@ static irqreturn_t pl08x_irq(int irq, void *dev) dma_cookie_complete(&tx->tx); list_add_tail(&tx->node, &plchan->done_list); - /* And start the next descriptor */ + /* + * And start the next descriptor (if any), + * otherwise free this channel. + */ if (!list_empty(&plchan->issued_list)) pl08x_start_next_txd(plchan); + else + pl08x_phy_free(plchan); } spin_unlock(&plchan->lock); |