On 09/12/2012 03:53 PM, Peter Ujfalusi wrote:
I need to look at this, but at first look we do wait for the drain in omap_stop_dma(). We used to use omap_stop_dma/omap_start_dma for pause/resume operations. But sDMA also have a bit: CDPi: PAUSE_LINK_LIST which should do what we are looking for. Need to read the relevant parts of the TRM, but AFAIK we are using normal mode with linked list (self linking). I already have the patch for this, I just need to test it on HW.
We can get the PAUSE/RESUME work either: 1. drivers/dma/omap-dma.c static int omap_dma_pause(struct omap_chan *c) { - /* FIXME: not supported by platform private API */ - return -EINVAL; + /* Only in cyclic mode */ + if (!c->cyclic) + return -EINVAL; + + if (!c->paused) { + omap_stop_dma(c->dma_ch); + c->paused = true; + } + + return 0; }
static int omap_dma_resume(struct omap_chan *c) { - /* FIXME: not supported by platform private API */ - return -EINVAL; + /* Only in cyclic mode */ + if (!c->cyclic) + return -EINVAL; + + if (c->paused) { + omap_start_dma(c->dma_ch); + c->paused = false; + } + + return 0; }
2. arch/arm/plat-omap/dma.c +void omap_pause_linked_dma(int lch) +{ + u32 l; + unsigned long flags; + + local_irq_save(flags); + l = p->dma_read(CDP, lch); + l |= 0x80; /* PAUSE_LINK_LIST */ + p->dma_write(l, CDP, lch); + local_irq_restore(flags); +} +EXPORT_SYMBOL(omap_pause_linked_dma); + +void omap_resume_linked_dma(int lch) +{ + u32 l; + unsigned long flags; + + local_irq_save(flags); + l = p->dma_read(CDP, lch); + l &= (~0x80); /* PAUSE_LINK_LIST */ + p->dma_write(l, CDP, lch); + local_irq_restore(flags); +} +EXPORT_SYMBOL(omap_resume_linked_dma);
drivers/dma/omap-dma.c static int omap_dma_pause(struct omap_chan *c) { - /* FIXME: not supported by platform private API */ - return -EINVAL; + /* Only in cyclic mode */ + if (!c->cyclic) + return -EINVAL; + + if (!c->paused) { + omap_pause_linked_dma(c->dma_ch); + c->paused = true; + } + + return 0; }
static int omap_dma_resume(struct omap_chan *c) { - /* FIXME: not supported by platform private API */ - return -EINVAL; + /* Only in cyclic mode */ + if (!c->cyclic) + return -EINVAL; + + if (c->paused) { + omap_resume_linked_dma(c->dma_ch); + c->paused = false; + } + + return 0; }
Both works fine (have tested it on BeagleBoard with mplayer). With [1] we have identical way of dealing with the PAUSE/RESUME as we had previously, so it is know to work fine on OMAP1/2/3/4/5
We have never used [2] in the past, but I think that is not going to work on OMAP1 and OMAP2420. Also we need to add code to arch/arm/plat-omap/dma.c for this...
I can resend the series with either of these to fix this regression caused by the dmaengine conversion (after cleanup off course).