linux-kernel - Re: [PATCH 8/8 resend] dw_dmac.c: Pass Channel Priority from platform

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Date:	Thu, 03 Mar 2011 00:16:01 +0530
From:	"Koul, Vinod" <vinod.koul@...el.com>
To:	Viresh Kumar <viresh.kumar@...com>
Cc:	dan.j.williams@...el.com, linus.walleij@...ricsson.com,
	amit.goel@...com, linux-kernel@...r.kernel.org,
	armando.visconti@...com, shiraz.hashim@...com,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 8/8 resend] dw_dmac.c: Pass Channel Priority from
 platform_data

On Mon, 2011-02-28 at 16:11 +0530, Viresh Kumar wrote:
> In Synopsys designware, channel priority is programmable. This patch adds
> support for passing channel priority through platform data. By default Ascending
> channel priority will be followed, i.e. channel 0 will get highest priority and
> channel 7 will get lowest.
> 
> Signed-off-by: Viresh Kumar <viresh.kumar@...com>
> ---
>  drivers/dma/dw_dmac.c      |   11 ++++++++++-
>  drivers/dma/dw_dmac_regs.h |    3 +++
>  include/linux/dw_dmac.h    |    4 +++-
>  3 files changed, 16 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/dma/dw_dmac.c b/drivers/dma/dw_dmac.c
> index 37ffd2c..edb3d3b 100644
> --- a/drivers/dma/dw_dmac.c
> +++ b/drivers/dma/dw_dmac.c
> @@ -896,8 +896,11 @@ static int dwc_alloc_chan_resources(struct dma_chan *chan)
>  		BUG_ON(!dws->dma_dev || dws->dma_dev != dw->dma.dev);
>  
>  		cfghi = dws->cfg_hi;
> -		cfglo = dws->cfg_lo;
> +		cfglo = dws->cfg_lo & ~DWC_CFGL_CH_PRIOR_MASK;
>  	}
> +
> +	cfglo |= DWC_CFGL_CH_PRIOR(dwc->priority);
> +
>  	channel_writel(dwc, CFG_LO, cfglo);
>  	channel_writel(dwc, CFG_HI, cfghi);
>  
> @@ -1320,6 +1323,12 @@ static int __init dw_probe(struct platform_device *pdev)
>  		else
>  			list_add(&dwc->chan.device_node, &dw->dma.channels);
>  
> +		/* 7 is highest priority & 0 is lowest. */
> +		if (pdata->chan_priority == CHAN_PRIORITY_ASCENDING)
> +			dwc->priority = 7 - i;
> +		else
> +			dwc->priority = i;
> +
>  		dwc->ch_regs = &__dw_regs(dw)->CHAN[i];
>  		spin_lock_init(&dwc->lock);
>  		dwc->mask = 1 << i;
> diff --git a/drivers/dma/dw_dmac_regs.h b/drivers/dma/dw_dmac_regs.h
> index d9a939f..6a8e6d3 100644
> --- a/drivers/dma/dw_dmac_regs.h
> +++ b/drivers/dma/dw_dmac_regs.h
> @@ -101,6 +101,8 @@ struct dw_dma_regs {
>  #define DWC_CTLH_BLOCK_TS_MASK	0x00000fff
>  
>  /* Bitfields in CFG_LO. Platform-configurable bits are in <linux/dw_dmac.h> */
> +#define DWC_CFGL_CH_PRIOR_MASK	(0x7 << 5)	/* priority mask */
> +#define DWC_CFGL_CH_PRIOR(x)	((x) << 5)	/* priority */
>  #define DWC_CFGL_CH_SUSP	(1 << 8)	/* pause xfer */
>  #define DWC_CFGL_FIFO_EMPTY	(1 << 9)	/* pause xfer */
>  #define DWC_CFGL_HS_DST		(1 << 10)	/* handshake w/dst */
> @@ -134,6 +136,7 @@ struct dw_dma_chan {
>  	struct dma_chan		chan;
>  	void __iomem		*ch_regs;
>  	u8			mask;
> +	u8			priority;
>  
>  	spinlock_t		lock;
>  
> diff --git a/include/linux/dw_dmac.h b/include/linux/dw_dmac.h
> index 057e883..53072c8 100644
> --- a/include/linux/dw_dmac.h
> +++ b/include/linux/dw_dmac.h
> @@ -22,6 +22,9 @@ struct dw_dma_platform_data {
>  #define CHAN_ALLOCATION_ASCENDING	0	/* zero to seven */
>  #define CHAN_ALLOCATION_DESCENDING	1	/* seven to zero */
>  	unsigned int	chan_allocation_order;
> +#define CHAN_PRIORITY_ASCENDING		0	/* chan0 highest */
> +#define CHAN_PRIORITY_DESCENDING	1	/* chan7 highest */
How about generic CHAN_ORDER_ASCENDING which you can use in both?

> +	unsigned int	chan_priority;
>  };
>  
>  /**
> @@ -65,7 +68,6 @@ struct dw_dma_slave {
>  #define DWC_CFGH_DST_PER(x)	((x) << 11)
>  
>  /* Platform-configurable bits in CFG_LO */
> -#define DWC_CFGL_PRIO(x)	((x) << 5)	/* priority */
>  #define DWC_CFGL_LOCK_CH_XFER	(0 << 12)	/* scope of LOCK_CH */
>  #define DWC_CFGL_LOCK_CH_BLOCK	(1 << 12)
>  #define DWC_CFGL_LOCK_CH_XACT	(2 << 12)


-- 
~Vinod

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