[PATCH] SPI: remove superfluous DMA buffer syncs on PL022

[PATCH] SPI: remove superfluous DMA buffer syncs on PL022

[Linus Walleij]

This removes the superfluous DMA buffer syncs identified by Russell
in the DMA support for PL022.

Cc: yuanyabin1978@sina.com
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Russell King <linux@arm.linux.org.uk>
Signed-off-by: Linus Walleij <linus.walleij@stericsson.com>
---
 drivers/spi/amba-pl022.c |   16 +++++-----------
 1 files changed, 5 insertions(+), 11 deletions(-)

diff --git a/drivers/spi/amba-pl022.c b/drivers/spi/amba-pl022.c
index 59b3948..521d3d9 100644
--- a/drivers/spi/amba-pl022.c
+++ b/drivers/spi/amba-pl022.c
@@ -794,12 +794,7 @@ static void dma_callback(void *data)
 	struct pl022 *pl022 = data;
 	struct spi_message *msg = pl022->cur_msg;
 
-	/* Sync in RX buffer to CPU */
 	BUG_ON(!pl022->sgt_rx.sgl);
-	dma_sync_sg_for_cpu(&pl022->adev->dev,
-			    pl022->sgt_rx.sgl,
-			    pl022->sgt_rx.nents,
-			    DMA_FROM_DEVICE);
 
 #ifdef VERBOSE_DEBUG
 	/*
@@ -812,6 +807,11 @@ static void dma_callback(void *data)
 		struct scatterlist *sg;
 		unsigned int i;
 
+		dma_sync_sg_for_cpu(&pl022->adev->dev,
+				    pl022->sgt_rx.sgl,
+				    pl022->sgt_rx.nents,
+				    DMA_FROM_DEVICE);
+
 		for_each_sg(pl022->sgt_rx.sgl, sg, pl022->sgt_rx.nents, i) {
 			dev_dbg(&pl022->adev->dev, "SPI RX SG ENTRY: %d", i);
 			print_hex_dump(KERN_ERR, "SPI RX: ",
@@ -1001,12 +1001,6 @@ static int configure_dma(struct pl022 *pl022)
 	if (sglen != pages)
 		goto err_tx_sgmap;
 
-	/* Synchronize the TX scatterlist, invalidate buffers, caches etc */
-	dma_sync_sg_for_device(&pl022->adev->dev,
-			       pl022->sgt_tx.sgl,
-			       pl022->sgt_tx.nents,
-			       DMA_TO_DEVICE);
-
 	/* Send both scatterlists */
 	rxdesc = rxchan->device->device_prep_slave_sg(rxchan,
 				      pl022->sgt_rx.sgl,
-- 
1.6.3.3

Re: [PATCH] SPI: remove superfluous DMA buffer syncs on PL022

[Grant Likely]

On Tue, Aug 17, 2010 at 4:08 PM, Linus Walleij
<linus.walleij-0IS4wlFg1OjSUeElwK9/Pw@public.gmane.org> wrote:
> This removes the superfluous DMA buffer syncs identified by Russell
> in the DMA support for PL022.
>
> Cc: yuanyabin1978-k+cT0dCbe1g@public.gmane.org
> Cc: Dan Williams <dan.j.williams-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
> Cc: Russell King <linux-lFZ/pmaqli7XmaaqVzeoHQ@public.gmane.org>
> Signed-off-by: Linus Walleij <linus.walleij-0IS4wlFg1OjSUeElwK9/Pw@public.gmane.org>

I haven't actually pushed out the spi-test branch yet.  Shall I squash
this patch into the previous one?

g.

> ---
>  drivers/spi/amba-pl022.c |   16 +++++-----------
>  1 files changed, 5 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/spi/amba-pl022.c b/drivers/spi/amba-pl022.c
> index 59b3948..521d3d9 100644
> --- a/drivers/spi/amba-pl022.c
> +++ b/drivers/spi/amba-pl022.c
> @@ -794,12 +794,7 @@ static void dma_callback(void *data)
>        struct pl022 *pl022 = data;
>        struct spi_message *msg = pl022->cur_msg;
>
> -       /* Sync in RX buffer to CPU */
>        BUG_ON(!pl022->sgt_rx.sgl);
> -       dma_sync_sg_for_cpu(&pl022->adev->dev,
> -                           pl022->sgt_rx.sgl,
> -                           pl022->sgt_rx.nents,
> -                           DMA_FROM_DEVICE);
>
>  #ifdef VERBOSE_DEBUG
>        /*
> @@ -812,6 +807,11 @@ static void dma_callback(void *data)
>                struct scatterlist *sg;
>                unsigned int i;
>
> +               dma_sync_sg_for_cpu(&pl022->adev->dev,
> +                                   pl022->sgt_rx.sgl,
> +                                   pl022->sgt_rx.nents,
> +                                   DMA_FROM_DEVICE);
> +
>                for_each_sg(pl022->sgt_rx.sgl, sg, pl022->sgt_rx.nents, i) {
>                        dev_dbg(&pl022->adev->dev, "SPI RX SG ENTRY: %d", i);
>                        print_hex_dump(KERN_ERR, "SPI RX: ",
> @@ -1001,12 +1001,6 @@ static int configure_dma(struct pl022 *pl022)
>        if (sglen != pages)
>                goto err_tx_sgmap;
>
> -       /* Synchronize the TX scatterlist, invalidate buffers, caches etc */
> -       dma_sync_sg_for_device(&pl022->adev->dev,
> -                              pl022->sgt_tx.sgl,
> -                              pl022->sgt_tx.nents,
> -                              DMA_TO_DEVICE);
> -
>        /* Send both scatterlists */
>        rxdesc = rxchan->device->device_prep_slave_sg(rxchan,
>                                      pl022->sgt_rx.sgl,
> --
> 1.6.3.3
>
>



-- 
Grant Likely, B.Sc., P.Eng.
Secret Lab Technologies Ltd.

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