From cecd87da83869ad4157295b87a2e51e38c3e03bf Mon Sep 17 00:00:00 2001 From: Linus Walleij Date: Thu, 4 Mar 2010 14:31:47 +0100 Subject: [PATCH] DMAENGINE: COH 901 318 rename confusing vars This fixes up the code with a lot of comments that make it readable, rename things with opaque names like "data" into something more appropriate, and remove some very confusing BUG() statements. Signed-off-by: Linus Walleij Signed-off-by: Dan Williams --- drivers/dma/coh901318.c | 103 ++++++++++++++++++++++++++++++------------------ 1 file changed, 65 insertions(+), 38 deletions(-) diff --git a/drivers/dma/coh901318.c b/drivers/dma/coh901318.c index 1656fdc..20889c9 100644 --- a/drivers/dma/coh901318.c +++ b/drivers/dma/coh901318.c @@ -37,7 +37,7 @@ struct coh901318_desc { struct list_head node; struct scatterlist *sg; unsigned int sg_len; - struct coh901318_lli *data; + struct coh901318_lli *lli; enum dma_data_direction dir; unsigned long flags; }; @@ -283,7 +283,7 @@ static int coh901318_start(struct coh901318_chan *cohc) } static int coh901318_prep_linked_list(struct coh901318_chan *cohc, - struct coh901318_lli *data) + struct coh901318_lli *lli) { int channel = cohc->id; void __iomem *virtbase = cohc->base->virtbase; @@ -292,18 +292,18 @@ static int coh901318_prep_linked_list(struct coh901318_chan *cohc, COH901318_CX_STAT_SPACING*channel) & COH901318_CX_STAT_ACTIVE); - writel(data->src_addr, + writel(lli->src_addr, virtbase + COH901318_CX_SRC_ADDR + COH901318_CX_SRC_ADDR_SPACING * channel); - writel(data->dst_addr, virtbase + + writel(lli->dst_addr, virtbase + COH901318_CX_DST_ADDR + COH901318_CX_DST_ADDR_SPACING * channel); - writel(data->link_addr, virtbase + COH901318_CX_LNK_ADDR + + writel(lli->link_addr, virtbase + COH901318_CX_LNK_ADDR + COH901318_CX_LNK_ADDR_SPACING * channel); - writel(data->control, virtbase + COH901318_CX_CTRL + + writel(lli->control, virtbase + COH901318_CX_CTRL + COH901318_CX_CTRL_SPACING * channel); return 0; @@ -565,29 +565,30 @@ static int coh901318_config(struct coh901318_chan *cohc, */ static struct coh901318_desc *coh901318_queue_start(struct coh901318_chan *cohc) { - struct coh901318_desc *cohd_que; + struct coh901318_desc *cohd; - /* start queued jobs, if any + /* + * start queued jobs, if any * TODO: transmit all queued jobs in one go */ - cohd_que = coh901318_first_queued(cohc); + cohd = coh901318_first_queued(cohc); - if (cohd_que != NULL) { + if (cohd != NULL) { /* Remove from queue */ - coh901318_desc_remove(cohd_que); + coh901318_desc_remove(cohd); /* initiate DMA job */ cohc->busy = 1; - coh901318_desc_submit(cohc, cohd_que); + coh901318_desc_submit(cohc, cohd); - coh901318_prep_linked_list(cohc, cohd_que->data); + coh901318_prep_linked_list(cohc, cohd->lli); - /* start dma job */ + /* start dma job on this channel */ coh901318_start(cohc); } - return cohd_que; + return cohd; } /* @@ -622,7 +623,7 @@ static void dma_tasklet(unsigned long data) cohc->completed = cohd_fin->desc.cookie; /* release the lli allocation and remove the descriptor */ - coh901318_lli_free(&cohc->base->pool, &cohd_fin->data); + coh901318_lli_free(&cohc->base->pool, &cohd_fin->lli); /* return desc to free-list */ coh901318_desc_remove(cohd_fin); @@ -666,23 +667,44 @@ static void dma_tasklet(unsigned long data) /* called from interrupt context */ static void dma_tc_handle(struct coh901318_chan *cohc) { - BUG_ON(!cohc->allocated && (list_empty(&cohc->active) || - list_empty(&cohc->queue))); - - if (!cohc->allocated) + /* + * If the channel is not allocated, then we shouldn't have + * any TC interrupts on it. + */ + if (!cohc->allocated) { + dev_err(COHC_2_DEV(cohc), "spurious interrupt from " + "unallocated channel\n"); return; + } spin_lock(&cohc->lock); + /* + * When we reach this point, at least one queue item + * should have been moved over from cohc->queue to + * cohc->active and run to completion, that is why we're + * getting a terminal count interrupt is it not? + * If you get this BUG() the most probable cause is that + * the individual nodes in the lli chain have IRQ enabled, + * so check your platform config for lli chain ctrl. + */ + BUG_ON(list_empty(&cohc->active)); + cohc->nbr_active_done++; + /* + * This attempt to take a job from cohc->queue, put it + * into cohc->active and start it. + */ if (coh901318_queue_start(cohc) == NULL) cohc->busy = 0; - BUG_ON(list_empty(&cohc->active)); - spin_unlock(&cohc->lock); + /* + * This tasklet will remove items from cohc->active + * and thus terminates them. + */ if (cohc_chan_conf(cohc)->priority_high) tasklet_hi_schedule(&cohc->tasklet); else @@ -870,7 +892,7 @@ static struct dma_async_tx_descriptor * coh901318_prep_memcpy(struct dma_chan *chan, dma_addr_t dest, dma_addr_t src, size_t size, unsigned long flags) { - struct coh901318_lli *data; + struct coh901318_lli *lli; struct coh901318_desc *cohd; unsigned long flg; struct coh901318_chan *cohc = to_coh901318_chan(chan); @@ -892,23 +914,23 @@ coh901318_prep_memcpy(struct dma_chan *chan, dma_addr_t dest, dma_addr_t src, if ((lli_len << MAX_DMA_PACKET_SIZE_SHIFT) < size) lli_len++; - data = coh901318_lli_alloc(&cohc->base->pool, lli_len); + lli = coh901318_lli_alloc(&cohc->base->pool, lli_len); - if (data == NULL) + if (lli == NULL) goto err; ret = coh901318_lli_fill_memcpy( - &cohc->base->pool, data, src, size, dest, + &cohc->base->pool, lli, src, size, dest, cohc_chan_param(cohc)->ctrl_lli_chained, ctrl_last); if (ret) goto err; - COH_DBG(coh901318_list_print(cohc, data)); + COH_DBG(coh901318_list_print(cohc, lli)); /* Pick a descriptor to handle this transfer */ cohd = coh901318_desc_get(cohc); - cohd->data = data; + cohd->lli = lli; cohd->flags = flags; cohd->desc.tx_submit = coh901318_tx_submit; @@ -926,7 +948,7 @@ coh901318_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl, unsigned long flags) { struct coh901318_chan *cohc = to_coh901318_chan(chan); - struct coh901318_lli *data; + struct coh901318_lli *lli; struct coh901318_desc *cohd; const struct coh901318_params *params; struct scatterlist *sg; @@ -999,13 +1021,13 @@ coh901318_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl, } pr_debug("Allocate %d lli:s for this transfer\n", len); - data = coh901318_lli_alloc(&cohc->base->pool, len); + lli = coh901318_lli_alloc(&cohc->base->pool, len); - if (data == NULL) + if (lli == NULL) goto err_dma_alloc; - /* initiate allocated data list */ - ret = coh901318_lli_fill_sg(&cohc->base->pool, data, sgl, sg_len, + /* initiate allocated lli list */ + ret = coh901318_lli_fill_sg(&cohc->base->pool, lli, sgl, sg_len, cohc_dev_addr(cohc), ctrl_chained, ctrl, @@ -1014,14 +1036,14 @@ coh901318_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl, if (ret) goto err_lli_fill; - COH_DBG(coh901318_list_print(cohc, data)); + COH_DBG(coh901318_list_print(cohc, lli)); /* Pick a descriptor to handle this transfer */ cohd = coh901318_desc_get(cohc); cohd->dir = direction; cohd->flags = flags; cohd->desc.tx_submit = coh901318_tx_submit; - cohd->data = data; + cohd->lli = lli; spin_unlock_irqrestore(&cohc->lock, flg); @@ -1065,7 +1087,12 @@ coh901318_issue_pending(struct dma_chan *chan) spin_lock_irqsave(&cohc->lock, flags); - /* Busy means that pending jobs are already being processed */ + /* + * Busy means that pending jobs are already being processed, + * and then there is no point in starting the queue: the + * terminal count interrupt on the channel will take the next + * job on the queue and execute it anyway. + */ if (!cohc->busy) coh901318_queue_start(cohc); @@ -1099,7 +1126,7 @@ coh901318_terminate_all(struct dma_chan *chan) while ((cohd = coh901318_first_active_get(cohc))) { /* release the lli allocation*/ - coh901318_lli_free(&cohc->base->pool, &cohd->data); + coh901318_lli_free(&cohc->base->pool, &cohd->lli); /* return desc to free-list */ coh901318_desc_remove(cohd); @@ -1108,7 +1135,7 @@ coh901318_terminate_all(struct dma_chan *chan) while ((cohd = coh901318_first_queued(cohc))) { /* release the lli allocation*/ - coh901318_lli_free(&cohc->base->pool, &cohd->data); + coh901318_lli_free(&cohc->base->pool, &cohd->lli); /* return desc to free-list */ coh901318_desc_remove(cohd); -- 1.8.2.3