Commit 5881826d authored by Nandor Han's avatar Nandor Han Committed by Greg Kroah-Hartman
Browse files

dmaengine: imx-sdma - update the residue calculation for cyclic channels 



The calculation of the DMA transaction residue supports only fixed
size data transfers. This implementation is not covering all
operations (e.g. data receiving) when we need to know the exact amount
of bytes transferred.

The loop channels handling was changed to clear the buffer
descriptor errors and use the bd->mode.count to calculate the
residue.

Tested-by: default avatarPeter Senna Tschudin <peter.senna@collabora.com>
Acked-by: default avatarPeter Senna Tschudin <peter.senna@collabora.com>
Reviewed-by: default avatarVinod Koul <vinod.koul@intel.com>
Signed-off-by: default avatarNandor Han <nandor.han@ge.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 15f30f51

drivers/dma/imx-sdma.c

+18 −2
Original line number Diff line number Diff line
@@ -651,6 +651,8 @@ static void sdma_event_disable(struct sdma_channel *sdmac, unsigned int event) 
static void sdma_update_channel_loop(struct sdma_channel *sdmac)

{

	struct sdma_buffer_descriptor *bd;

	int error = 0;

	enum dma_status	old_status = sdmac->status;



	/*

	 * loop mode. Iterate over descriptors, re-setup them and
@@ -662,10 +664,20 @@ static void sdma_update_channel_loop(struct sdma_channel *sdmac) 
		if (bd->mode.status & BD_DONE)

			break;



		if (bd->mode.status & BD_RROR)

		if (bd->mode.status & BD_RROR) {

			bd->mode.status &= ~BD_RROR;

			sdmac->status = DMA_ERROR;

			error = -EIO;

		}



	       /*

		* We use bd->mode.count to calculate the residue, since contains

		* the number of bytes present in the current buffer descriptor.

		*/



		sdmac->chn_real_count = bd->mode.count;

		bd->mode.status |= BD_DONE;

		bd->mode.count = sdmac->period_len;



		/*

		 * The callback is called from the interrupt context in order
@@ -679,6 +691,9 @@ static void sdma_update_channel_loop(struct sdma_channel *sdmac) 


		sdmac->buf_tail++;

		sdmac->buf_tail %= sdmac->num_bd;



		if (error)

			sdmac->status = old_status;

	}

}
@@ -1349,7 +1364,8 @@ static enum dma_status sdma_tx_status(struct dma_chan *chan, 
	u32 residue;



	if (sdmac->flags & IMX_DMA_SG_LOOP)

		residue = (sdmac->num_bd - sdmac->buf_tail) * sdmac->period_len;

		residue = (sdmac->num_bd - sdmac->buf_tail) *

			   sdmac->period_len - sdmac->chn_real_count;

	else

		residue = sdmac->chn_count - sdmac->chn_real_count;

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