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Message-ID: <576BE16F.6060406@globallogic.com>
Date: Thu, 23 Jun 2016 16:17:35 +0300
From: "ivan.khoronzhuk" <ivan.khoronzhuk@...aro.org>
To: Grygorii Strashko <grygorii.strashko@...com>,
"David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org,
Mugunthan V N <mugunthanvnm@...com>
Cc: Sekhar Nori <nsekhar@...com>, linux-kernel@...r.kernel.org,
linux-omap@...r.kernel.org,
Ivan Khoronzhuk <ivan.khoronzhuk@...aro.org>
Subject: Re: [PATCH] net: ethernet: ti: cpdma: switch to use genalloc
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@...aro.org>
> Signed-off-by: Grygorii Strashko <grygorii.strashko@...com>
Tested-by: Ivan Khoronzhuk <ivan.khoronzhuk@...aro.org>
> ---
> 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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