Re: [PATCH 2/2] DMA: Freescale: update driver to support 8-channel DMA engine

Scott Wood
2013-07-02T23:13:23Z

On 06/30/2013 10:46:18 PM, hongbo.zhang@freescale.com wrote:
> From: Hongbo Zhang <hongbo.zhang@freescale.com>
>
> This patch adds support to 8-channel DMA engine, thus the driver
> works for both
> the new 8-channel and the legacy 4-channel DMA engines.
>
> Signed-off-by: Hongbo Zhang <hongbo.zhang@freescale.com>
> ---
> drivers/dma/fsldma.c | 48
> ++++++++++++++++++++++++++++++++++--------------
> drivers/dma/fsldma.h | 4 ++--
> 2 files changed, 36 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/dma/fsldma.c b/drivers/dma/fsldma.c
> index 4fc2980..0f453ea 100644
> --- a/drivers/dma/fsldma.c
> +++ b/drivers/dma/fsldma.c
> @@ -1119,27 +1119,33 @@ static irqreturn_t fsldma_ctrl_irq(int irq,
> void *data)
> struct fsldma_device *fdev = data;
> struct fsldma_chan *chan;
> unsigned int handled = 0;
> - u32 gsr, mask;
> + u8 chan_sr[round_up(FSL_DMA_MAX_CHANS_PER_DEVICE, 4)];
> + u32 gsr;
> int i;
>
> - gsr = (fdev->feature & FSL_DMA_BIG_ENDIAN) ? in_be32(fdev->regs)
> - :
> in_le32(fdev->regs);
> - mask = 0xff000000;
> - dev_dbg(fdev->dev, "IRQ: gsr 0x%.8x\n", gsr);
> + memset(&chan_sr, 0, sizeof(chan_sr));
> + gsr = (fdev->feature & FSL_DMA_BIG_ENDIAN) ?
> in_be32(fdev->regs0)
> + :
> in_le32(fdev->regs0);
> + memcpy(&chan_sr[0], &gsr, 4);
> + dev_dbg(fdev->dev, "IRQ: gsr0 0x%.8x\n", gsr);
> +
> + if (of_device_is_compatible(fdev->dev->of_node,
> "fsl,eloplus-dma2")) {

NACK; Figure out what sort of device you've got when you first probe
the device, and store the information for later. Do not call device
tree stuff in an interrupt handler.

> + gsr = (fdev->feature & FSL_DMA_BIG_ENDIAN) ?
> + in_be32(fdev->regs1) : in_le32(fdev->regs1);
> + memcpy(&chan_sr[4], &gsr, 4);
> + dev_dbg(fdev->dev, "IRQ: gsr1 0x%.8x\n", gsr);
> + }

Do these memcpy()s get inlined? If not (and maybe even if they do),
it'd be better to use a union instead.

Wait a second -- how are we even getting into this code on these new
DMA controllers? All 85xx-family DMA controllers use fsldma_chan_irq
directly.

> @@ -1341,13 +1349,22 @@ static int fsldma_of_probe(struct
> platform_device *op)
> INIT_LIST_HEAD(&fdev->common.channels);
>
> /* ioremap the registers for use */
> - fdev->regs = of_iomap(op->dev.of_node, 0);
> - if (!fdev->regs) {
> - dev_err(&op->dev, "unable to ioremap registers\n");
> + fdev->regs0 = of_iomap(op->dev.of_node, 0);
> + if (!fdev->regs0) {
> + dev_err(&op->dev, "unable to ioremap register0\n");
> err = -ENOMEM;
> goto out_free_fdev;
> }
>
> + if (of_device_is_compatible(op->dev.of_node,
> "fsl,eloplus-dma2")) {

Not "fsl,eloplusplus-dma"? :-)

More seriously, if we're sticking with this "elo" naming, maybe
"fsl,elo3-dma" would be better. It would be odd to have "2" in the
name of the third generation of this hardware.

> diff --git a/drivers/dma/fsldma.h b/drivers/dma/fsldma.h
> index f5c3879..880664d 100644
> --- a/drivers/dma/fsldma.h
> +++ b/drivers/dma/fsldma.h
> @@ -112,10 +112,10 @@ struct fsldma_chan_regs {
> };
>
> struct fsldma_chan;
> -#define FSL_DMA_MAX_CHANS_PER_DEVICE 4
> +#define FSL_DMA_MAX_CHANS_PER_DEVICE 8
>
> struct fsldma_device {
> - void __iomem *regs; /* DGSR register base */
> + void __iomem *regs0, *regs1; /* DGSR registers */

Either give these meaningful names, or use an array. Or both (dgsr[2]).

Or just get rid of this, since I don't see why we need DGSR1 at all, as
previously noted.

-Scott