From 13bbfb5c4eb4fc85bf977245f9b3624df0187184 Mon Sep 17 00:00:00 2001 From: Daniel Mack Date: Mon, 26 May 2014 14:52:34 +0200 Subject: dma: cppi41: handle 0-length packets When a 0-length packet is received on the bus, desc->pd0 yields 1, which confuses the driver's users. This information is clearly wrong and not in accordance to the datasheet, but it's been observed on an AM335x board, very reproducible. Fix this by looking at bit 19 in PD2 of the completed packet. This bit will tell us if a zero-length packet was received on a queue. If it's set, ignore the value in PD0 and report a total length of 0 instead. Signed-off-by: Daniel Mack Signed-off-by: Vinod Koul diff --git a/drivers/dma/cppi41.c b/drivers/dma/cppi41.c index d028f36..8f8b0b6 100644 --- a/drivers/dma/cppi41.c +++ b/drivers/dma/cppi41.c @@ -86,6 +86,9 @@ #define USBSS_IRQ_PD_COMP (1 << 2) +/* Packet Descriptor */ +#define PD2_ZERO_LENGTH (1 << 19) + struct cppi41_channel { struct dma_chan chan; struct dma_async_tx_descriptor txd; @@ -307,7 +310,7 @@ static irqreturn_t cppi41_irq(int irq, void *data) __iormb(); while (val) { - u32 desc; + u32 desc, len; q_num = __fls(val); val &= ~(1 << q_num); @@ -319,9 +322,13 @@ static irqreturn_t cppi41_irq(int irq, void *data) q_num, desc); continue; } - c->residue = pd_trans_len(c->desc->pd6) - - pd_trans_len(c->desc->pd0); + if (c->desc->pd2 & PD2_ZERO_LENGTH) + len = 0; + else + len = pd_trans_len(c->desc->pd0); + + c->residue = pd_trans_len(c->desc->pd6) - len; dma_cookie_complete(&c->txd); c->txd.callback(c->txd.callback_param); } -- cgit v0.10.2 From d1a792f3b4072bfac4150bb62aa34917b77fdb6d Mon Sep 17 00:00:00 2001 From: Russell King - ARM Linux Date: Wed, 25 Jun 2014 13:00:33 +0100 Subject: Update imx-sdma cyclic handling to report residue I received a report this morning from one of the Novena developers that the behaviour of the iMX6 ASoC codec driver (using imx-pcm-dma.c) was sub-optimal under high system load. While there are issues relating to system load remaining, upon reviewing the ASoC imx-pcm-dma.c driver, it was noticed that it not using the residue support, because SDMA doesn't support it. This has the effect that SDMA has to make multiple calls into the ASoC and ALSA code, one for each period. Since ALSA's snd_pcm_elapsed() does not need to be called multiple times and it is entirely sufficient to call it once to update ALSA with the current buffer position via the pointer method, we can do better here. We can also avoid stopping the DMA entirely, just like real cyclic DMA implementations behave. While this means that we replay some old samples, this is a nicer behaviour than having audio stop and restart. The changes to achieve this are relatively minor - imx-sdma.c can track where the DMA is to the nearest descriptor boundary - it does this already when deciding how many callbacks to issue. In doing this, buf_tail always points at the descriptor which will complete next. The residue is defined by the bytes remaining to the end of the buffer, when the buffer is viewed as a single block of memory [start...end]. So, when we start out, there's a full buffer worth of residue, and this counts down as we approach the end of the buffer, eventually becoming zero at the end, before returning to the full buffer worth when we wrap back to the start. Moving the walking of the descriptors into the interrupt handler means that we can update the BD_DONE flag at interrupt time, thus avoiding a delayed tasklet stopping the cyclic DMA. This means that the residue can be calculated from (total descriptors - buf_tail) * descriptor size. This is what the change below does. We update imx-pcm-dma.c to remove the NO_RESIDUE flag since we now provide the residue. Signed-off-by: Russell King Tested-by: Shawn Guo Signed-off-by: Vinod Koul diff --git a/drivers/dma/imx-sdma.c b/drivers/dma/imx-sdma.c index 1287146..14867e3 100644 --- a/drivers/dma/imx-sdma.c +++ b/drivers/dma/imx-sdma.c @@ -255,6 +255,7 @@ struct sdma_channel { enum dma_slave_buswidth word_size; unsigned int buf_tail; unsigned int num_bd; + unsigned int period_len; struct sdma_buffer_descriptor *bd; dma_addr_t bd_phys; unsigned int pc_from_device, pc_to_device; @@ -593,6 +594,12 @@ static void sdma_event_disable(struct sdma_channel *sdmac, unsigned int event) static void sdma_handle_channel_loop(struct sdma_channel *sdmac) { + if (sdmac->desc.callback) + sdmac->desc.callback(sdmac->desc.callback_param); +} + +static void sdma_update_channel_loop(struct sdma_channel *sdmac) +{ struct sdma_buffer_descriptor *bd; /* @@ -611,9 +618,6 @@ static void sdma_handle_channel_loop(struct sdma_channel *sdmac) bd->mode.status |= BD_DONE; sdmac->buf_tail++; sdmac->buf_tail %= sdmac->num_bd; - - if (sdmac->desc.callback) - sdmac->desc.callback(sdmac->desc.callback_param); } } @@ -669,6 +673,9 @@ static irqreturn_t sdma_int_handler(int irq, void *dev_id) int channel = fls(stat) - 1; struct sdma_channel *sdmac = &sdma->channel[channel]; + if (sdmac->flags & IMX_DMA_SG_LOOP) + sdma_update_channel_loop(sdmac); + tasklet_schedule(&sdmac->tasklet); __clear_bit(channel, &stat); @@ -1129,6 +1136,7 @@ static struct dma_async_tx_descriptor *sdma_prep_dma_cyclic( sdmac->status = DMA_IN_PROGRESS; sdmac->buf_tail = 0; + sdmac->period_len = period_len; sdmac->flags |= IMX_DMA_SG_LOOP; sdmac->direction = direction; @@ -1225,9 +1233,15 @@ static enum dma_status sdma_tx_status(struct dma_chan *chan, struct dma_tx_state *txstate) { struct sdma_channel *sdmac = to_sdma_chan(chan); + u32 residue; + + if (sdmac->flags & IMX_DMA_SG_LOOP) + residue = (sdmac->num_bd - sdmac->buf_tail) * sdmac->period_len; + else + residue = sdmac->chn_count - sdmac->chn_real_count; dma_set_tx_state(txstate, chan->completed_cookie, chan->cookie, - sdmac->chn_count - sdmac->chn_real_count); + residue); return sdmac->status; } diff --git a/sound/soc/fsl/imx-pcm-dma.c b/sound/soc/fsl/imx-pcm-dma.c index 0849b7b..0db94f49 100644 --- a/sound/soc/fsl/imx-pcm-dma.c +++ b/sound/soc/fsl/imx-pcm-dma.c @@ -59,7 +59,6 @@ int imx_pcm_dma_init(struct platform_device *pdev) { return devm_snd_dmaengine_pcm_register(&pdev->dev, &imx_dmaengine_pcm_config, - SND_DMAENGINE_PCM_FLAG_NO_RESIDUE | SND_DMAENGINE_PCM_FLAG_COMPAT); } EXPORT_SYMBOL_GPL(imx_pcm_dma_init); -- cgit v0.10.2