Re: [PATCH] net: ethernet: ti: cpdma: switch to use genalloc

["ivan.khoronzhuk" <ivan.khoronzhuk@xxxxxxxxxx>]

On 23.06.16 15:36, Grygorii Strashko wrote:
> TI CPDMA currently uses a bitmap for tracking descriptors alloactions
> allocations, but The genalloc already handles the same and can be used
> as with special memory (SRAM) as with DMA cherent memory chank
> (dma_alloc_coherent()). Hence, switch to using genalloc and add
> desc_num property for each channel for limitation of max number of
> allowed descriptors for each CPDMA channel. This patch do not affect
> on net throuput.
>
> Cc: Ivan Khoronzhuk <ivan.khoronzhuk@xxxxxxxxxx>
> Signed-off-by: Grygorii Strashko <grygorii.strashko@xxxxxx>

Tested-by: Ivan Khoronzhuk <ivan.khoronzhuk@xxxxxxxxxx>

> ---
> Testing
> TCP window: 256K, bandwidth in Mbits/sec:
>   host: iperf -s
>   device: iperf -c  172.22.39.17 -t600 -i5 -d -w128K
>
> AM437x-idk, 1Gbps link
>   before: : 341.60, after: 232+123=355
> am57xx-beagle-x15, 1Gbps link
>   before: : 1112.80, after: 814+321=1135
> am335x-boneblack, 100Mbps link
>   before: : 162.40, after: 72+93=165
>
>   drivers/net/ethernet/ti/davinci_cpdma.c | 136 +++++++++++++++-----------------
>   1 file changed, 62 insertions(+), 74 deletions(-)
>
> diff --git a/drivers/net/ethernet/ti/davinci_cpdma.c b/drivers/net/ethernet/ti/davinci_cpdma.c
> index 18bf3a8..03b9882 100644
> --- a/drivers/net/ethernet/ti/davinci_cpdma.c
> +++ b/drivers/net/ethernet/ti/davinci_cpdma.c
> @@ -21,7 +21,7 @@
>   #include <linux/dma-mapping.h>
>   #include <linux/io.h>
>   #include <linux/delay.h>
> -
> +#include <linux/genalloc.h>
>   #include "davinci_cpdma.h"
>
>   /* DMA Registers */
> @@ -87,9 +87,8 @@ struct cpdma_desc_pool {
>   	void			*cpumap;	/* dma_alloc map */
>   	int			desc_size, mem_size;
>   	int			num_desc, used_desc;
> -	unsigned long		*bitmap;
>   	struct device		*dev;
> -	spinlock_t		lock;
> +	struct gen_pool		*gen_pool;
>   };
>
>   enum cpdma_state {
> @@ -117,6 +116,7 @@ struct cpdma_chan {
>   	int				chan_num;
>   	spinlock_t			lock;
>   	int				count;
> +	u32				desc_num;
>   	u32				mask;
>   	cpdma_handler_fn		handler;
>   	enum dma_data_direction		dir;
> @@ -145,6 +145,20 @@ struct cpdma_chan {
>   				 (directed << CPDMA_TO_PORT_SHIFT));	\
>   	} while (0)
>
> +static void cpdma_desc_pool_destroy(struct cpdma_desc_pool *pool)
> +{
> +	if (!pool)
> +		return;
> +
> +	WARN_ON(pool->used_desc);
> +	if (pool->cpumap) {
> +		dma_free_coherent(pool->dev, pool->mem_size, pool->cpumap,
> +				  pool->phys);
> +	} else {
> +		iounmap(pool->iomap);
> +	}
> +}
> +
>   /*
>    * Utility constructs for a cpdma descriptor pool.  Some devices (e.g. davinci
>    * emac) have dedicated on-chip memory for these descriptors.  Some other
> @@ -155,24 +169,25 @@ static struct cpdma_desc_pool *
>   cpdma_desc_pool_create(struct device *dev, u32 phys, dma_addr_t hw_addr,
>   				int size, int align)
>   {
> -	int bitmap_size;
>   	struct cpdma_desc_pool *pool;
> +	int ret;
>
>   	pool = devm_kzalloc(dev, sizeof(*pool), GFP_KERNEL);
>   	if (!pool)
> -		goto fail;
> -
> -	spin_lock_init(&pool->lock);
> +		goto gen_pool_create_fail;
>
>   	pool->dev	= dev;
>   	pool->mem_size	= size;
>   	pool->desc_size	= ALIGN(sizeof(struct cpdma_desc), align);
>   	pool->num_desc	= size / pool->desc_size;
>
> -	bitmap_size  = (pool->num_desc / BITS_PER_LONG) * sizeof(long);
> -	pool->bitmap = devm_kzalloc(dev, bitmap_size, GFP_KERNEL);
> -	if (!pool->bitmap)
> -		goto fail;
> +	pool->gen_pool = devm_gen_pool_create(dev, ilog2(pool->desc_size), -1,
> +					      "cpdma");
> +	if (IS_ERR(pool->gen_pool)) {
> +		dev_err(dev, "pool create failed %ld\n",
> +			PTR_ERR(pool->gen_pool));
> +		goto gen_pool_create_fail;
> +	}
>
>   	if (phys) {
>   		pool->phys  = phys;
> @@ -185,24 +200,22 @@ cpdma_desc_pool_create(struct device *dev, u32 phys, dma_addr_t hw_addr,
>   		pool->phys = pool->hw_addr; /* assumes no IOMMU, don't use this value */
>   	}
>
> -	if (pool->iomap)
> -		return pool;
> -fail:
> -	return NULL;
> -}
> -
> -static void cpdma_desc_pool_destroy(struct cpdma_desc_pool *pool)
> -{
> -	if (!pool)
> -		return;
> +	if (!pool->iomap)
> +		goto gen_pool_create_fail;
>
> -	WARN_ON(pool->used_desc);
> -	if (pool->cpumap) {
> -		dma_free_coherent(pool->dev, pool->mem_size, pool->cpumap,
> -				  pool->phys);
> -	} else {
> -		iounmap(pool->iomap);
> +	ret = gen_pool_add_virt(pool->gen_pool, (unsigned long)pool->iomap,
> +				pool->phys, pool->mem_size, -1);
> +	if (ret < 0) {
> +		dev_err(dev, "pool add failed %d\n", ret);
> +		goto gen_pool_add_virt_fail;
>   	}
> +
> +	return pool;
> +
> +gen_pool_add_virt_fail:
> +	cpdma_desc_pool_destroy(pool);
> +gen_pool_create_fail:
> +	return NULL;
>   }
>
>   static inline dma_addr_t desc_phys(struct cpdma_desc_pool *pool,
> @@ -210,7 +223,7 @@ static inline dma_addr_t desc_phys(struct cpdma_desc_pool *pool,
>   {
>   	if (!desc)
>   		return 0;
> -	return pool->hw_addr + (__force long)desc - (__force long)pool->iomap;
> +	return gen_pool_virt_to_phys(pool->gen_pool, (unsigned long)desc);
>   }
>
>   static inline struct cpdma_desc __iomem *
> @@ -220,47 +233,23 @@ desc_from_phys(struct cpdma_desc_pool *pool, dma_addr_t dma)
>   }
>
>   static struct cpdma_desc __iomem *
> -cpdma_desc_alloc(struct cpdma_desc_pool *pool, int num_desc, bool is_rx)
> +cpdma_desc_alloc(struct cpdma_desc_pool *pool)
>   {
> -	unsigned long flags;
> -	int index;
> -	int desc_start;
> -	int desc_end;
>   	struct cpdma_desc __iomem *desc = NULL;
>
> -	spin_lock_irqsave(&pool->lock, flags);
> -
> -	if (is_rx) {
> -		desc_start = 0;
> -		desc_end = pool->num_desc/2;
> -	 } else {
> -		desc_start = pool->num_desc/2;
> -		desc_end = pool->num_desc;
> -	}
> -
> -	index = bitmap_find_next_zero_area(pool->bitmap,
> -				desc_end, desc_start, num_desc, 0);
> -	if (index < desc_end) {
> -		bitmap_set(pool->bitmap, index, num_desc);
> -		desc = pool->iomap + pool->desc_size * index;
> +	desc = (struct cpdma_desc __iomem *)gen_pool_alloc(pool->gen_pool,
> +							   pool->desc_size);
> +	if (desc)
>   		pool->used_desc++;
> -	}
>
> -	spin_unlock_irqrestore(&pool->lock, flags);
>   	return desc;
>   }
>
>   static void cpdma_desc_free(struct cpdma_desc_pool *pool,
>   			    struct cpdma_desc __iomem *desc, int num_desc)
>   {
> -	unsigned long flags, index;
> -
> -	index = ((unsigned long)desc - (unsigned long)pool->iomap) /
> -		pool->desc_size;
> -	spin_lock_irqsave(&pool->lock, flags);
> -	bitmap_clear(pool->bitmap, index, num_desc);
> +	gen_pool_free(pool->gen_pool, (unsigned long)desc, pool->desc_size);
>   	pool->used_desc--;
> -	spin_unlock_irqrestore(&pool->lock, flags);
>   }
>
>   struct cpdma_ctlr *cpdma_ctlr_create(struct cpdma_params *params)
> @@ -516,6 +505,7 @@ struct cpdma_chan *cpdma_chan_create(struct cpdma_ctlr *ctlr, int chan_num,
>   	chan->state	= CPDMA_STATE_IDLE;
>   	chan->chan_num	= chan_num;
>   	chan->handler	= handler;
> +	chan->desc_num = ctlr->pool->num_desc / 2;
>
>   	if (is_rx_chan(chan)) {
>   		chan->hdp	= ctlr->params.rxhdp + offset;
> @@ -675,7 +665,13 @@ int cpdma_chan_submit(struct cpdma_chan *chan, void *token, void *data,
>   		goto unlock_ret;
>   	}
>
> -	desc = cpdma_desc_alloc(ctlr->pool, 1, is_rx_chan(chan));
> +	if (chan->count >= chan->desc_num)	{
> +		chan->stats.desc_alloc_fail++;
> +		ret = -ENOMEM;
> +		goto unlock_ret;
> +	}
> +
> +	desc = cpdma_desc_alloc(ctlr->pool);
>   	if (!desc) {
>   		chan->stats.desc_alloc_fail++;
>   		ret = -ENOMEM;
> @@ -721,24 +717,16 @@ EXPORT_SYMBOL_GPL(cpdma_chan_submit);
>
>   bool cpdma_check_free_tx_desc(struct cpdma_chan *chan)
>   {
> -	unsigned long flags;
> -	int index;
> -	bool ret;
>   	struct cpdma_ctlr	*ctlr = chan->ctlr;
>   	struct cpdma_desc_pool	*pool = ctlr->pool;
> +	unsigned long flags;
> +	bool	free_tx_desc;
>
> -	spin_lock_irqsave(&pool->lock, flags);
> -
> -	index = bitmap_find_next_zero_area(pool->bitmap,
> -				pool->num_desc, pool->num_desc/2, 1, 0);
> -
> -	if (index < pool->num_desc)
> -		ret = true;
> -	else
> -		ret = false;
> -
> -	spin_unlock_irqrestore(&pool->lock, flags);
> -	return ret;
> +	spin_lock_irqsave(&chan->lock, flags);
> +	free_tx_desc = (chan->count < chan->desc_num) &&
> +			 gen_pool_avail(pool->gen_pool);
> +	spin_unlock_irqrestore(&chan->lock, flags);
> +	return free_tx_desc;
>   }
>   EXPORT_SYMBOL_GPL(cpdma_check_free_tx_desc);
>
> @@ -772,7 +760,6 @@ static int __cpdma_chan_process(struct cpdma_chan *chan)
>   	unsigned long			flags;
>
>   	spin_lock_irqsave(&chan->lock, flags);
> -
>   	desc = chan->head;
>   	if (!desc) {
>   		chan->stats.empty_dequeue++;
> @@ -796,6 +783,7 @@ static int __cpdma_chan_process(struct cpdma_chan *chan)
>   			    CPDMA_DESC_PORT_MASK);
>
>   	chan->head = desc_from_phys(pool, desc_read(desc, hw_next));
> +
>   	chan_write(chan, cp, desc_dma);
>   	chan->count--;
>   	chan->stats.good_dequeue++;
--
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