Subject: [PATCH 2/3] dmaengine: at_xdmac: simplify channel configuration stuff

From: [email-masked] (Vinod Koul)
Date: Mon, 8 Dec 2014 16:09:18 +0530

On Wed, Nov 26, 2014 at 05:22:28PM +0100, Ludovic Desroches wrote:
> Using the cc field of the descriptor simplifies the management of the channel
> configuration.
> 
> Signed-off-by: Ludovic Desroches <[email-masked]>
> ---
>  drivers/dma/at_xdmac.c | 33 +++++++++++++--------------------
>  1 file changed, 13 insertions(+), 20 deletions(-)
> 
> diff --git a/drivers/dma/at_xdmac.c b/drivers/dma/at_xdmac.c
> index bc4b018..94b714e 100644
> --- a/drivers/dma/at_xdmac.c
> +++ b/drivers/dma/at_xdmac.c
> @@ -200,6 +200,7 @@ struct at_xdmac_chan {
>  	u8				memif;		/* Memory Interface */
>  	u32				per_src_addr;
>  	u32				per_dst_addr;
> +	u32				save_cc;
>  	u32				save_cim;
>  	u32				save_cnda;
>  	u32				save_cndc;
> @@ -357,14 +358,7 @@ static void at_xdmac_start_xfer(struct at_xdmac_chan *atchan,
>  	 */
>  	if (is_slave_direction(first->direction)) {
>  		reg = AT_XDMAC_CNDC_NDVIEW_NDV1;
> -		if (first->direction == DMA_MEM_TO_DEV)
> -			atchan->cfg[AT_XDMAC_CUR_CFG] =
> -				atchan->cfg[AT_XDMAC_MEM_TO_DEV_CFG];
> -		else
> -			atchan->cfg[AT_XDMAC_CUR_CFG] =
> -				atchan->cfg[AT_XDMAC_DEV_TO_MEM_CFG];
> -		at_xdmac_chan_write(atchan, AT_XDMAC_CC,
> -				    atchan->cfg[AT_XDMAC_CUR_CFG]);
> +		at_xdmac_chan_write(atchan, AT_XDMAC_CC, first->lld.mbr_cfg);
how is this related to adding cc field?

>  	} else {
>  		/*
>  		 * No need to write AT_XDMAC_CC reg, it will be done when the
> @@ -568,7 +562,6 @@ at_xdmac_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
>  	struct at_xdmac_desc	*first = NULL, *prev = NULL;
>  	struct scatterlist	*sg;
>  	int			i;
> -	u32			cfg;
>  	unsigned int		xfer_size = 0;
>  
>  	if (!sgl)
> @@ -615,17 +608,17 @@ at_xdmac_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
>  		if (direction == DMA_DEV_TO_MEM) {
>  			desc->lld.mbr_sa = atchan->per_src_addr;
>  			desc->lld.mbr_da = mem;
> -			cfg = atchan->cfg[AT_XDMAC_DEV_TO_MEM_CFG];
> +			desc->lld.mbr_cfg = atchan->cfg[AT_XDMAC_DEV_TO_MEM_CFG];
>  		} else {
>  			desc->lld.mbr_sa = mem;
>  			desc->lld.mbr_da = atchan->per_dst_addr;
> -			cfg = atchan->cfg[AT_XDMAC_MEM_TO_DEV_CFG];
> +			desc->lld.mbr_cfg = atchan->cfg[AT_XDMAC_MEM_TO_DEV_CFG];
>  		}
> -		desc->lld.mbr_ubc = AT_XDMAC_MBR_UBC_NDV1		/* next descriptor view */
> -			| AT_XDMAC_MBR_UBC_NDEN				/* next descriptor dst parameter update */
> -			| AT_XDMAC_MBR_UBC_NSEN				/* next descriptor src parameter update */
> -			| (i == sg_len - 1 ? 0 : AT_XDMAC_MBR_UBC_NDE)	/* descriptor fetch */
> -			| len / (1 << at_xdmac_get_dwidth(cfg));	/* microblock length */
> +		desc->lld.mbr_ubc = AT_XDMAC_MBR_UBC_NDV1			/* next descriptor view */
> +			| AT_XDMAC_MBR_UBC_NDEN					/* next descriptor dst parameter update */
> +			| AT_XDMAC_MBR_UBC_NSEN					/* next descriptor src parameter update */
> +			| (i == sg_len - 1 ? 0 : AT_XDMAC_MBR_UBC_NDE)		/* descriptor fetch */
> +			| len / (1 << at_xdmac_get_dwidth(desc->lld.mbr_cfg));	/* microblock length */
>  		dev_dbg(chan2dev(chan),
>  			 "%s: lld: mbr_sa=%pad, mbr_da=%pad, mbr_ubc=0x%08x\n",
>  			 __func__, &desc->lld.mbr_sa, &desc->lld.mbr_da, desc->lld.mbr_ubc);
> @@ -889,7 +882,7 @@ at_xdmac_tx_status(struct dma_chan *chan, dma_cookie_t cookie,
>  	enum dma_status		ret;
>  	int			residue;
>  	u32			cur_nda, mask, value;
> -	u8			dwidth = at_xdmac_get_dwidth(atchan->cfg[AT_XDMAC_CUR_CFG]);
> +	u8			dwidth = 0;
>  
>  	ret = dma_cookie_status(chan, cookie, txstate);
>  	if (ret == DMA_COMPLETE)
> @@ -933,6 +926,7 @@ at_xdmac_tx_status(struct dma_chan *chan, dma_cookie_t cookie,
>  	 */
>  	descs_list = &desc->descs_list;
>  	list_for_each_entry_safe(desc, _desc, descs_list, desc_node) {
> +		dwidth = at_xdmac_get_dwidth(desc->lld.mbr_cfg);
>  		residue -= (desc->lld.mbr_ubc & 0xffffff) << dwidth;
>  		if ((desc->lld.mbr_nda & 0xfffffffc) == cur_nda)
>  			break;
> @@ -1276,6 +1270,7 @@ static int atmel_xdmac_suspend(struct device *dev)
>  	list_for_each_entry_safe(chan, _chan, &atxdmac->dma.channels, device_node) {
>  		struct at_xdmac_chan	*atchan = to_at_xdmac_chan(chan);
>  
> +		atchan->save_cc = at_xdmac_chan_read(atchan, AT_XDMAC_CC);
okay finally we end us using the new field, the code before that seems to
use existing lld.mbr_cfg, shouldnt this be another change explaining the
changes...

>  		if (at_xdmac_chan_is_cyclic(atchan)) {
>  			if (!at_xdmac_chan_is_paused(atchan))
>  				at_xdmac_device_pause(chan);
> @@ -1298,7 +1293,6 @@ static int atmel_xdmac_resume(struct device *dev)
>  	struct at_xdmac_chan	*atchan;
>  	struct dma_chan		*chan, *_chan;
>  	int			i;
> -	u32			cfg;
>  
>  	clk_prepare_enable(atxdmac->clk);
>  
> @@ -1313,8 +1307,7 @@ static int atmel_xdmac_resume(struct device *dev)
>  	at_xdmac_write(atxdmac, AT_XDMAC_GE, atxdmac->save_gs);
>  	list_for_each_entry_safe(chan, _chan, &atxdmac->dma.channels, device_node) {
>  		atchan = to_at_xdmac_chan(chan);
> -		cfg = atchan->cfg[AT_XDMAC_CUR_CFG];
> -		at_xdmac_chan_write(atchan, AT_XDMAC_CC, cfg);
> +		at_xdmac_chan_write(atchan, AT_XDMAC_CC, atchan->save_cc);
only thing here wer are saving and restoring from save_cc. How does that
impact rest of the code above?

-- 
~Vinod

>  		if (at_xdmac_chan_is_cyclic(atchan)) {
>  			at_xdmac_chan_write(atchan, AT_XDMAC_CNDA, atchan->save_cnda);
>  			at_xdmac_chan_write(atchan, AT_XDMAC_CNDC, atchan->save_cndc);
> -- 
> 2.0.3
> 

--