diff options
Diffstat (limited to 'drivers/dma/edma.c')
| -rw-r--r-- | drivers/dma/edma.c | 53 |
1 files changed, 51 insertions, 2 deletions
diff --git a/drivers/dma/edma.c b/drivers/dma/edma.c index 16fe773fb..e3d7fcb69 100644 --- a/drivers/dma/edma.c +++ b/drivers/dma/edma.c @@ -113,6 +113,9 @@ #define GET_NUM_REGN(x) ((x & 0x300000) >> 20) /* bits 20-21 */ #define CHMAP_EXIST BIT(24) +/* CCSTAT register */ +#define EDMA_CCSTAT_ACTV BIT(4) + /* * Max of 20 segments per channel to conserve PaRAM slots * Also note that MAX_NR_SG should be atleast the no.of periods @@ -484,7 +487,7 @@ static void edma_read_slot(struct edma_cc *ecc, unsigned slot, */ static int edma_alloc_slot(struct edma_cc *ecc, int slot) { - if (slot > 0) { + if (slot >= 0) { slot = EDMA_CHAN_SLOT(slot); /* Requesting entry paRAM slot for a HW triggered channel. */ if (ecc->chmap_exist && slot < ecc->num_channels) @@ -1680,9 +1683,20 @@ static void edma_issue_pending(struct dma_chan *chan) spin_unlock_irqrestore(&echan->vchan.lock, flags); } +/* + * This limit exists to avoid a possible infinite loop when waiting for proof + * that a particular transfer is completed. This limit can be hit if there + * are large bursts to/from slow devices or the CPU is never able to catch + * the DMA hardware idle. On an AM335x transfering 48 bytes from the UART + * RX-FIFO, as many as 55 loops have been seen. + */ +#define EDMA_MAX_TR_WAIT_LOOPS 1000 + static u32 edma_residue(struct edma_desc *edesc) { bool dst = edesc->direction == DMA_DEV_TO_MEM; + int loop_count = EDMA_MAX_TR_WAIT_LOOPS; + struct edma_chan *echan = edesc->echan; struct edma_pset *pset = edesc->pset; dma_addr_t done, pos; int i; @@ -1691,7 +1705,32 @@ static u32 edma_residue(struct edma_desc *edesc) * We always read the dst/src position from the first RamPar * pset. That's the one which is active now. */ - pos = edma_get_position(edesc->echan->ecc, edesc->echan->slot[0], dst); + pos = edma_get_position(echan->ecc, echan->slot[0], dst); + + /* + * "pos" may represent a transfer request that is still being + * processed by the EDMACC or EDMATC. We will busy wait until + * any one of the situations occurs: + * 1. the DMA hardware is idle + * 2. a new transfer request is setup + * 3. we hit the loop limit + */ + while (edma_read(echan->ecc, EDMA_CCSTAT) & EDMA_CCSTAT_ACTV) { + /* check if a new transfer request is setup */ + if (edma_get_position(echan->ecc, + echan->slot[0], dst) != pos) { + break; + } + + if (!--loop_count) { + dev_dbg_ratelimited(echan->vchan.chan.device->dev, + "%s: timeout waiting for PaRAM update\n", + __func__); + break; + } + + cpu_relax(); + } /* * Cyclic is simple. Just subtract pset[0].addr from pos. @@ -2314,6 +2353,10 @@ static int edma_probe(struct platform_device *pdev) edma_set_chmap(&ecc->slave_chans[i], ecc->dummy_slot); } + ecc->dma_slave.filter.map = info->slave_map; + ecc->dma_slave.filter.mapcnt = info->slavecnt; + ecc->dma_slave.filter.fn = edma_filter_fn; + ret = dma_async_device_register(&ecc->dma_slave); if (ret) { dev_err(dev, "slave ddev registration failed (%d)\n", ret); @@ -2421,7 +2464,13 @@ static struct platform_driver edma_driver = { }, }; +static int edma_tptc_probe(struct platform_device *pdev) +{ + return 0; +} + static struct platform_driver edma_tptc_driver = { + .probe = edma_tptc_probe, .driver = { .name = "edma3-tptc", .of_match_table = edma_tptc_of_ids, |