Date:	Mon, 09 Jan 2012 16:41:33 +0530
From:	Ravi Kumar V <kumarrav@...eaurora.org>
To:	Daniel Walker <dwalker@...o99.com>
CC:	vinod.koul@...el.com, dan.j.williams@...el.com, arnd@...db.de,
	linux-arch@...r.kernel.org, davidb@...eaurora.org,
	bryanh@...eaurora.org, linux@....linux.org.uk, tsoni@...lcomm.com,
	johlstei@...lcomm.com, linux-kernel@...r.kernel.org,
	linux-arm-msm@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v2 2/2] msm: DMAEngine: Add DMAEngine driver based on
 old MSM DMA APIs

On 1/7/2012 7:29 AM, Daniel Walker wrote:
> On Fri, 2012-01-06 at 18:17 +0530, Ravi Kumar V wrote:
>> Add DMAEngine based driver using the old MSM DMA APIs internally.
>> The benefit of this approach is that not all the drivers
>> have to get converted to DMAEngine APIs simultaneosly while
>> both the drivers can stay enabled in the kernel. The client
>> drivers using the old MSM APIs directly can now convert to
>> DMAEngine one by one.
>>
>> Change-Id: I3647ed7b8c73b3078dfa8877a3560db3cb0a2373
>> Signed-off-by: Ravi Kumar V<kumarrav@...eaurora.org>
>> ---
>>   arch/arm/mach-msm/include/mach/dma.h |   33 ++
>>   drivers/dma/Kconfig                  |   12 +
>>   drivers/dma/Makefile                 |    1 +
>>   drivers/dma/msm-dma.c                |  764 ++++++++++++++++++++++++++++++++++
>>   4 files changed, 810 insertions(+), 0 deletions(-)
>>   create mode 100644 drivers/dma/msm-dma.c
>>
>> diff --git a/arch/arm/mach-msm/include/mach/dma.h b/arch/arm/mach-msm/include/mach/dma.h
>> index 05583f5..34f4dac 100644
>> --- a/arch/arm/mach-msm/include/mach/dma.h
>> +++ b/arch/arm/mach-msm/include/mach/dma.h
>> @@ -18,6 +18,39 @@
>>   #include<linux/list.h>
>>   #include<mach/msm_iomap.h>
>>
>> +#define msm_dma_set_crci(sg, crci)	(((sg)->private_data) = \
>> +					(((sg)->private_data)&  ~(0x7F8)) | \
>> +					crci)
>> +#define msm_dma_set_endian(sg, en)	(((sg)->private_data) = \
>> +					(((sg)->private_data)&  ~(0x1F800)) | \
>> +					en)
>> +#define msm_dma_set_tcb(sg, tcb)	(((sg)->private_data) = \
>> +					(((sg)->private_data)&  ~(0x80000)) | \
>> +					tcb)
>> +#define sg_dma_offset(sg)               ((sg)->offset)
>> +#define sg_dma_private_data(sg)         ((sg)->private_data)
>> +#define box_dma_row_address(box)        ((box)->dma_row_address)
>> +#define box_dma_row_len(box)            ((box)->dma_row_len)
>> +#define box_dma_row_num(box)            ((box)->dma_row_num)
>> +#define box_dma_row_offset(box)         ((box)->dma_row_offset)
>> +#define box_dma_private_data(box)       ((box)->private_data)
>> +
>> +#define MSM_DMA_CMD_MASK		0x9FFF8
>> +#define MSM_DMA_CMD_SHIFT		0
>> +#define MSM_BOX_SRC_RLEN_MASK		0xFFFF
>> +#define MSM_BOX_SRC_RLEN_SHIFT		16
>> +#define MSM_BOX_SRC_RNUM_MASK		0xFFFF
>> +#define MSM_BOX_SRC_RNUM_SHIFT		16
>> +#define MSM_BOX_SRC_ROFFSET_MASK	0xFFFF
>> +#define MSM_BOX_SRC_ROFFSET_SHIFT	16
>> +#define MSM_BOX_DST_RLEN_MASK		0xFFFF
>> +#define MSM_BOX_DST_RNUM_MASK		0xFFFF
>> +#define MSM_BOX_DST_ROFFSET_MASK	0xFFFF
>> +#define MSM_BOX_MODE_CMD		0x3
>> +
>> +#define FORCED_FLUSH		0
>> +#define GRACEFUL_FLUSH          1
>
> Could be an enum ..
>
>>   struct msm_dmov_errdata {
>>   	uint32_t flush[6];
>>   };
>> diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig
>> index ab8f469..3e69f42 100644
>> --- a/drivers/dma/Kconfig
>> +++ b/drivers/dma/Kconfig
>> @@ -245,6 +245,18 @@ config EP93XX_DMA
>>   	help
>>   	  Enable support for the Cirrus Logic EP93xx M2P/M2M DMA controller.
>>
>> +config MSM_DMA
>> +	tristate "Qualcomm MSM DMA support"
>> +	depends on ARCH_MSM
>> +	select DMA_ENGINE
>> +	help
>> +	  Support the Qualcomm DMA engine. This engine is integrated into
>> +	  Qualcomm chips.
>> +
>> +	  Say Y here if you have such a chipset.
>> +
>> +	  If unsure, say N.
>> +
>>   config DMA_ENGINE
>>   	bool
>>
>> diff --git a/drivers/dma/Makefile b/drivers/dma/Makefile
>> index 30cf3b1..56593f0 100644
>> --- a/drivers/dma/Makefile
>> +++ b/drivers/dma/Makefile
>> @@ -19,6 +19,7 @@ obj-$(CONFIG_COH901318) += coh901318.o coh901318_lli.o
>>   obj-$(CONFIG_AMCC_PPC440SPE_ADMA) += ppc4xx/
>>   obj-$(CONFIG_IMX_SDMA) += imx-sdma.o
>>   obj-$(CONFIG_IMX_DMA) += imx-dma.o
>> +obj-$(CONFIG_MSM_DMA) += msm-dma.o
>>   obj-$(CONFIG_MXS_DMA) += mxs-dma.o
>>   obj-$(CONFIG_TIMB_DMA) += timb_dma.o
>>   obj-$(CONFIG_STE_DMA40) += ste_dma40.o ste_dma40_ll.o
>> diff --git a/drivers/dma/msm-dma.c b/drivers/dma/msm-dma.c
>> new file mode 100644
>> index 0000000..51d9a2b
>> --- /dev/null
>> +++ b/drivers/dma/msm-dma.c
>> @@ -0,0 +1,764 @@
>> +/* Copyright (c) 2011, Code Aurora Forum. All rights reserved.
>> + *
>> + * This program is free software; you can redistribute it and/or modify
>> + * it under the terms of the GNU General Public License version 2 and
>> + * only version 2 as published by the Free Software Foundation.
>> + *
>> + * This program is distributed in the hope that it will be useful,
>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
>> + * GNU General Public License for more details.
>> + */
>> +#include<linux/init.h>
>> +#include<linux/slab.h>
>> +#include<linux/clk.h>
>> +#include<linux/err.h>
>> +#include<linux/io.h>
>> +#include<linux/interrupt.h>
>> +#include<linux/module.h>
>> +#include<linux/platform_device.h>
>> +#include<linux/spinlock.h>
>> +#include<linux/dmapool.h>
>> +#include<linux/dmaengine.h>
>> +#include<linux/dma-mapping.h>
>> +
>> +#include<mach/dma.h>
>> +
>> +#define SD3_CHAN_START			0
>> +#define MSM_DMOV_CRCI_COUNT		16
>> +#define MSM_DMA_MAX_CHANS_PER_DEVICE	16
>> +#define MAX_TRANSFER_LENGTH		65535
>> +#define NO_ERR_CHAN_STATUS		0x80000002
>> +#define to_msm_chan(chan) container_of(chan, struct msm_dma_chan, channel)
>> +
>> +struct msm_dma_chan {
>> +	int chan_id;
>> +	dma_cookie_t completed_cookie;
>> +	dma_cookie_t error_cookie;
>> +	spinlock_t lock;
>> +	struct list_head active_list;
>> +	struct list_head pending_list;
>> +	struct dma_chan channel;
>> +	struct dma_pool *desc_pool;
>> +	struct device *dev;
>> +	int max_len;
>> +	int err;
>> +	struct tasklet_struct tasklet;
>> +};
>> +
>> +struct msm_dma_device {
>> +	void __iomem *base;
>> +	struct device *dev;
>> +	struct dma_device common;
>> +	struct msm_dma_chan *chan[MSM_DMA_MAX_CHANS_PER_DEVICE];
>> +};
>> +
>> +struct msm_dma_desc_hw {
>> +	unsigned int cmd_list_ptr;
>> +} __aligned(8);
>> +
>> +/* Single Item Mode */
>> +struct adm_cmd_t {
>> +	unsigned int cmd_cntrl;
>> +	unsigned int src;
>> +	unsigned int dst;
>> +	unsigned int len;
>> +};
>> +
>> +struct adm_box_cmd_t {
>> +	uint32_t cmd_cntrl;
>> +	uint32_t src_row_addr;
>> +	uint32_t dst_row_addr;
>> +	uint32_t src_dst_len;
>> +	uint32_t num_rows;
>> +	uint32_t row_offset;
>> +};
>> +
>> +struct msm_dma_desc_sw {
>> +	struct msm_dma_desc_hw hw;
>> +	struct adm_cmd_t *vaddr_cmd;
>> +	struct adm_box_cmd_t *vaddr_box_cmd;
>> +	size_t coherent_size;
>> +	dma_addr_t paddr_cmd_list;
>> +	struct list_head node;
>> +	struct msm_dmov_cmd dmov_cmd;
>> +	struct dma_async_tx_descriptor async_tx;
>> +} __aligned(8);
>> +
>> +static int msm_dma_alloc_chan_resources(struct dma_chan *dchan)
>> +{
>> +	struct msm_dma_chan *chan = to_msm_chan(dchan);
>> +
>> +	/* Has this channel already been allocated? */
>> +	if (chan->desc_pool)
>> +		return 1;
>> +
>> +	/*
>> +	 * We need the descriptor to be aligned to 8bytes
>> +	 * for meeting ADM specification requirement.
>> +	 */
>> +	chan->desc_pool = dma_pool_create("msm_dma_desc_pool",
>> +					chan->dev,
>> +					sizeof(struct msm_dma_desc_sw),
>> +				__alignof__(struct msm_dma_desc_sw), 0);
>> +	if (!chan->desc_pool) {
>> +		dev_err(chan->dev, "unable to allocate channel %d "
>> +				"descriptor pool\n", chan->chan_id);
>> +		return -ENOMEM;
>> +	}
>> +
>> +	chan->completed_cookie = 1;
>> +	dchan->cookie = 1;
>> +
>> +	/* there is at least one descriptor free to be allocated */
>> +	return 1;
>> +}
>> +
>> +static void msm_dma_free_desc_list(struct msm_dma_chan *chan,
>> +						struct list_head *list)
>> +{
>> +	struct msm_dma_desc_sw *desc, *_desc;
>> +
>> +	list_for_each_entry_safe(desc, _desc, list, node) {
>> +		list_del(&desc->node);
>> +		dma_pool_free(chan->desc_pool, desc, desc->async_tx.phys);
>> +	}
>> +}
>> +
>> +static void msm_dma_free_chan_resources(struct dma_chan *dchan)
>> +{
>> +	struct msm_dma_chan *chan = to_msm_chan(dchan);
>> +	unsigned long flags;
>> +
>> +	dev_dbg(chan->dev, "Free all channel resources.\n");
>> +	spin_lock_irqsave(&chan->lock, flags);
>> +	msm_dma_free_desc_list(chan,&chan->active_list);
>> +	msm_dma_free_desc_list(chan,&chan->pending_list);
>> +	spin_unlock_irqrestore(&chan->lock, flags);
>> +
>> +	dma_pool_destroy(chan->desc_pool);
>> +	chan->desc_pool = NULL;
>> +}
>> +
>> +static enum dma_status msm_dma_desc_status(struct msm_dma_chan *chan,
>> +					struct msm_dma_desc_sw *desc)
>> +{
>> +	return dma_async_is_complete(desc->async_tx.cookie,
>> +					chan->completed_cookie,
>> +					chan->channel.cookie);
>> +}
>> +
>> +static void msm_chan_desc_cleanup(struct msm_dma_chan *chan)
>> +{
>> +	struct msm_dma_desc_sw *desc, *_desc;
>> +	unsigned long flags;
>> +
>> +	dev_dbg(chan->dev, "Cleaning completed descriptor of channel %d\n",
>> +							chan->chan_id);
>> +	spin_lock_irqsave(&chan->lock, flags);
>> +
>> +	list_for_each_entry_safe(desc, _desc,&chan->active_list, node) {
>> +		dma_async_tx_callback callback;
>> +		void *callback_param;
>> +
>> +		if (msm_dma_desc_status(chan, desc) == DMA_IN_PROGRESS)
>> +			break;
>> +
>> +		/* Remove from the list of running transactions */
>> +		list_del(&desc->node);
>> +
>> +		/* Run the link descriptor callback function */
>> +		callback = desc->async_tx.callback;
>> +		callback_param = desc->async_tx.callback_param;
>> +		if (callback) {
>> +			spin_unlock_irqrestore(&chan->lock, flags);
>> +			callback(callback_param);
>
> Are you sure unlocking here is safe? at_hdmac.c holds the lock the
> entire time, and fsldma.c deletes the entire list, then runs the
> operations.
>
>> +			spin_lock_irqsave(&chan->lock, flags);
>> +		}
>> +
>> +		/* Run any dependencies, then free the descriptor */
>> +		dma_run_dependencies(&desc->async_tx);
>> +		spin_unlock_irqrestore(&chan->lock, flags);
>> +
>> +		if (desc->vaddr_cmd) {
>> +			dma_free_coherent(chan->dev, desc->coherent_size,
>> +						(void *)desc->vaddr_cmd,
>> +							desc->paddr_cmd_list);
>> +		} else {
>> +			dma_free_coherent(chan->dev, desc->coherent_size,
>> +						(void *)desc->vaddr_box_cmd,
>> +							desc->paddr_cmd_list);
>> +		}
>> +		spin_lock_irqsave(&chan->lock, flags);
>> +		dma_pool_free(chan->desc_pool, desc, desc->async_tx.phys);
>> +	}
>> +
>> +	spin_unlock_irqrestore(&chan->lock, flags);
>> +}
>> +
>> +static void dma_do_tasklet(unsigned long data)
>> +{
>> +	struct msm_dma_chan *chan = (struct msm_dma_chan *)data;
>> +	msm_chan_desc_cleanup(chan);
>> +}
>> +
>> +static void
>> +msm_dma_complete_func(struct msm_dmov_cmd *cmd,
>> +				unsigned int result,
>> +				struct msm_dmov_errdata *err)
>> +{
>> +	unsigned long flags;
>> +	struct msm_dma_desc_sw *desch = container_of(cmd,
>> +				struct msm_dma_desc_sw, dmov_cmd);
>> +	struct msm_dma_chan *chan = to_msm_chan(desch->async_tx.chan);
>> +
>> +	spin_lock_irqsave(&chan->lock, flags);
>> +
>> +	if ((result != NO_ERR_CHAN_STATUS)&&  err)
>> +		chan->error_cookie = desch->async_tx.cookie;
>> +	chan->completed_cookie = desch->async_tx.cookie;
>> +
>> +	tasklet_schedule(&chan->tasklet);
>> +
>> +	spin_unlock_irqrestore(&chan->lock, flags);
>> +}
>> +
>> +/*
>> + *  Passes transfer descriptors to DMA hardware.
>> + */
>> +static void msm_dma_issue_pending(struct dma_chan *dchan)
>> +{
>> +	struct msm_dma_chan *chan = to_msm_chan(dchan);
>> +	struct msm_dma_desc_sw *desch;
>> +	unsigned long flags;
>> +
>> +	if (chan->err)
>> +		return;
>> +
>> +	spin_lock_irqsave(&chan->lock, flags);
>> +
>> +	if (list_empty(&chan->pending_list))
>> +		goto out_unlock;
>> +
>> +	desch = list_first_entry(&chan->pending_list, struct msm_dma_desc_sw,
>> +									node);
>> +	list_del(&desch->node);
>> +	desch->dmov_cmd.complete_func = msm_dma_complete_func;
>> +	desch->dmov_cmd.execute_func = NULL;
>> +	desch->dmov_cmd.cmdptr = DMOV_CMD_ADDR(desch->async_tx.phys);
>> +	list_add_tail(&desch->node,&chan->active_list);
>> +	mb();
>> +	msm_dmov_enqueue_cmd(chan->chan_id,&desch->dmov_cmd);
>> +out_unlock:
>> +	spin_unlock_irqrestore(&chan->lock, flags);
>> +}
>> +
>> +/*
>> + *  Assignes cookie for each transfer descriptor passed.
>> + *  Returns
>> + *	Assigend cookie for success.
>> + *	Error value for failure.
>> + */
>> +static dma_cookie_t msm_dma_tx_submit(struct dma_async_tx_descriptor *tx)
>> +{
>> +	struct msm_dma_chan *chan = to_msm_chan(tx->chan);
>> +	struct msm_dma_desc_sw *desc = container_of(tx,
>> +	struct msm_dma_desc_sw, async_tx);
>> +	unsigned long flags;
>> +	dma_cookie_t cookie = -EBUSY;
>> +
>> +	if (chan->err)
>> +		return cookie;
>> +
>> +	spin_lock_irqsave(&chan->lock, flags);
>> +
>> +	/*
>> +	 * assign cookies to all of the software descriptors
>> +	 * that make up this transaction
>> +	 */
>> +	cookie = chan->channel.cookie;
>> +	cookie++;
>> +	if (cookie<  0)
>> +		cookie = DMA_MIN_COOKIE;
>> +
>> +	desc->async_tx.cookie = cookie;
>> +	chan->channel.cookie = cookie;
>> +
>> +	/* put this transaction onto the tail of the pending queue */
>> +	list_add_tail(&desc->node,&chan->pending_list);
>> +
>> +	spin_unlock_irqrestore(&chan->lock, flags);
>> +
>> +	return cookie;
>> +}
>> +
>> +/*
>> + *  Returns the DMA transfer status of a particular cookie
>> + */
>> +static enum dma_status msm_tx_status(struct dma_chan *dchan,
>> +					dma_cookie_t cookie,
>> +				struct dma_tx_state *txstate)
>> +{
>> +	struct msm_dma_chan *chan = to_msm_chan(dchan);
>> +	dma_cookie_t last_used;
>> +	dma_cookie_t last_complete;
>> +	enum dma_status status;
>> +
>> +	last_used = dchan->cookie;
>> +	last_complete = chan->completed_cookie;
>> +
>> +	dma_set_tx_state(txstate, last_complete, last_used, 0);
>> +
>> +	status = dma_async_is_complete(cookie, last_complete, last_used);
>> +
>> +	if (status != DMA_IN_PROGRESS)
>> +		if (chan->error_cookie == cookie)
>> +			status = DMA_ERROR;
>> +
>> +	return status;
>> +}
>> +
>> +static struct msm_dma_desc_sw *msm_dma_alloc_descriptor(
>> +				struct msm_dma_chan *chan,
>> +				int cmd_cnt,
>> +				int mask)
>> +{
>> +	struct msm_dma_desc_sw *desc;
>> +	dma_addr_t pdesc_addr;
>> +	dma_addr_t paddr_cmd_list;
>> +	void *err = NULL;
>> +
>> +	desc = dma_pool_alloc(chan->desc_pool, GFP_ATOMIC,&pdesc_addr);
>> +	if (!desc) {
>> +		dev_dbg(chan->dev, "out of memory for desc\n");
>> +		return ERR_CAST(desc);
>> +	}
>> +
>> +	memset(desc, 0, sizeof(*desc));
>> +	desc->async_tx.phys = pdesc_addr;
>> +
>> +	if (mask == DMA_BOX) {
>> +		desc->coherent_size = sizeof(struct adm_box_cmd_t);
>> +		desc->vaddr_box_cmd = dma_alloc_coherent(chan->dev,
>> +				sizeof(struct adm_box_cmd_t),
>> +				&paddr_cmd_list, GFP_ATOMIC);
>> +		if (!desc->vaddr_box_cmd) {
>> +			dev_dbg(chan->dev, "out of memory for desc\n");
>> +			err = desc->vaddr_box_cmd;
>> +			goto fail;
>> +		}
>> +	} else {
>> +		desc->coherent_size = sizeof(struct adm_cmd_t)*cmd_cnt;
>> +
>> +		desc->vaddr_cmd = dma_alloc_coherent(chan->dev,
>> +				sizeof(struct adm_cmd_t)*cmd_cnt,
>> +				&paddr_cmd_list, GFP_ATOMIC);
>> +
>> +		if (!desc->vaddr_cmd) {
>> +			dev_dbg(chan->dev, "out of memory for desc\n");
>> +			err = desc->vaddr_cmd;
>> +			goto fail;
>> +		}
>> +	}
>> +
>> +	dma_async_tx_descriptor_init(&desc->async_tx,&chan->channel);
>> +	desc->async_tx.tx_submit = msm_dma_tx_submit;
>> +	desc->paddr_cmd_list = paddr_cmd_list;
>> +	desc->hw.cmd_list_ptr = (paddr_cmd_list>>  3) | CMD_PTR_LP;
>> +	return desc;
>> +fail:
>> +	dma_pool_free(chan->desc_pool, desc, desc->async_tx.phys);
>> +	return ERR_CAST(err);
>> +}
>> +
>> +/*
>> + *  Prepares the transfer descriptors for SG transaction.
>> + *  Returns
>> + *	address of dma_async_tx_descriptor for success.
>> + *	Pointer of error value for failure.
>> + */
>> +static struct dma_async_tx_descriptor *msm_dma_prep_sg(
>> +		struct dma_chan *dchan,
>> +		struct scatterlist *dst_sg, unsigned int dst_nents,
>> +		struct scatterlist *src_sg, unsigned int src_nents,
>> +		unsigned long flags)
>> +{
>> +
>> +	struct msm_dma_chan *chan;
>> +	struct msm_dma_desc_sw *new;
>> +	size_t copy, len;
>> +	int cmd_cnt = 0;
>> +	int first = 0;
>> +	int i;
>> +	dma_addr_t src;
>> +	dma_addr_t dst;
>> +	struct adm_cmd_t *cmdlist_vaddr;
>> +	struct scatterlist *sg;
>> +
>> +	if (!dchan)
>> +		return ERR_PTR(-EINVAL);
>> +
>> +	if (dst_nents == 0 || src_nents == 0)
>> +		return ERR_PTR(-EINVAL);
>> +	if (!dst_sg || !src_sg)
>> +		return ERR_PTR(-EINVAL);
>> +
>> +	if (dst_nents != src_nents)
>> +		return ERR_PTR(-EINVAL);
>> +
>> +	chan = to_msm_chan(dchan);
>> +
>> +	cmd_cnt = src_nents;
>> +
>> +	for (i = 0; i<  src_nents; i++) {
>> +		len = sg_dma_len(src_sg + i);
>> +		if (len != MAX_TRANSFER_LENGTH)
>> +			cmd_cnt += len/MAX_TRANSFER_LENGTH;
>> +	}
>> +
>> +	new = msm_dma_alloc_descriptor(chan, cmd_cnt, DMA_SG);
>> +
>> +	if (!new) {
>> +		dev_err(chan->dev,
>> +			"No free memory for link descriptor\n");
>> +		return ERR_PTR(-ENOMEM);
>> +	}
>> +
>> +	cmdlist_vaddr = new->vaddr_cmd;
>> +
>> +	for_each_sg(src_sg, sg, src_nents, i) {
>> +		len = sg_dma_len(sg);
>> +		src = sg_dma_address(sg);
>> +		do {
>> +			copy = (len>= MAX_TRANSFER_LENGTH) ?
>> +						MAX_TRANSFER_LENGTH : len;
>> +			cmdlist_vaddr->src = src;
>> +			cmdlist_vaddr->len = copy;
>> +			cmdlist_vaddr->cmd_cntrl =
>> +			(sg_dma_private_data(sg)&  MSM_DMA_CMD_MASK);
>> +			if (first == 0) {
>> +				if (cmd_cnt == 1)
>> +					cmdlist_vaddr->cmd_cntrl = CMD_LC |
>> +							CMD_OCB | CMD_OCU;
>> +				else
>> +					cmdlist_vaddr->cmd_cntrl = CMD_OCB;
>> +				first = 1;
>> +			}
>> +			cmdlist_vaddr++;
>> +			len -= copy;
>> +			src += copy;
>> +		} while (len);
>> +	}
>> +	if (cmd_cnt>  1) {
>> +		cmdlist_vaddr--;
>> +		cmdlist_vaddr->cmd_cntrl |= CMD_LC | CMD_OCU;
>> +	}
>> +
>> +	cmdlist_vaddr = new->vaddr_cmd;
>> +
>> +	for_each_sg(dst_sg, sg, src_nents, i) {
>> +		len = sg_dma_len(sg);
>> +		dst = sg_dma_address(sg);
>> +		do {
>> +			copy = (len>= MAX_TRANSFER_LENGTH) ?
>> +					MAX_TRANSFER_LENGTH : len;
>> +			cmdlist_vaddr->dst = dst;
>> +			cmdlist_vaddr++;
>> +			len -= copy;
>> +			dst += copy;
>> +		} while (len);
>> +
>> +	}
>> +
>> +#ifdef DEBUG
>> +	cmdlist_vaddr = new->vaddr_cmd;
>> +	i = 0;
>> +	do {
>> +		dev_dbg(chan->dev, "cmd %d src 0x%x dst 0x%x len 0x%x "
>> +						"cntrl 0x%x\n",
>> +				i, cmdlist_vaddr->src, cmdlist_vaddr->dst,
>
> Doesn't look like "i" has a log of meaning here.
>
> If it were me I'd make the two #ifdef DEBUG blocks into helper
> functions, then you could combine them into a single block. Would look
> cleaner too I think.
>
>> +				cmdlist_vaddr->len, cmdlist_vaddr->cmd_cntrl);
>> +			cmdlist_vaddr++;
>> +	} while (!((cmdlist_vaddr-1)->cmd_cntrl&  CMD_LC));
>> +#endif
>
>> +	new->async_tx.flags = flags;
>> +	new->async_tx.cookie = -EBUSY;
>> +
>> +	return&new->async_tx;
>> +}
>> +
>> +/*
>> + *  Prepares the transfer descriptors for BOX transaction.
>> + *  Returns
>> + *      address of dma_async_tx_descriptor for success.
>> + *      Pointer of error value for failure.
>> + */
>> +static struct dma_async_tx_descriptor *msm_dma_prep_box(
>> +		struct dma_chan *dchan,
>> +		struct dma_box_list *dst_box, struct dma_box_list *src_box,
>> +		unsigned int num_list,	unsigned long flags)
>> +{
>> +	struct msm_dma_chan *chan;
>> +	struct msm_dma_desc_sw *new;
>> +	int cmd_cnt = 0;
>> +	int first = 0;
>> +	int i;
>> +	struct adm_box_cmd_t *box_cmd_vaddr;
>> +
>> +	if (!dchan)
>> +		return ERR_PTR(-EINVAL);
>> +
>> +	if (num_list == 0)
>> +		return ERR_PTR(-EINVAL);
>> +	if (!dst_box || !src_box)
>> +		return ERR_PTR(-EINVAL);
>> +
>> +	chan = to_msm_chan(dchan);
>> +
>> +	cmd_cnt = num_list;
>> +
>> +	new = msm_dma_alloc_descriptor(chan, cmd_cnt, DMA_BOX);
>> +
>> +	if (!new) {
>> +		dev_err(chan->dev,
>> +			"No free memory for link descriptor\n");
>> +		return ERR_PTR(-ENOMEM);
>> +	}
>> +	box_cmd_vaddr = new->vaddr_box_cmd;
>> +
>> +	for (i = 0; i<  num_list; i++) {
>> +
>> +		box_cmd_vaddr->src_row_addr =
>> +				box_dma_row_address(src_box + i);
>> +		box_cmd_vaddr->src_dst_len =
>> +				(box_dma_row_len(src_box + i)&
>> +				MSM_BOX_SRC_RLEN_MASK)<<
>> +				MSM_BOX_SRC_RLEN_SHIFT;
>> +		box_cmd_vaddr->cmd_cntrl =
>> +				(box_dma_private_data(src_box + i)&
>> +				MSM_DMA_CMD_MASK) | MSM_BOX_MODE_CMD;
>> +
>> +		box_cmd_vaddr->num_rows = (box_dma_row_num(src_box + i)&
>> +				MSM_BOX_SRC_RNUM_MASK)<<
>> +				MSM_BOX_SRC_RNUM_SHIFT;
>> +
>> +		box_cmd_vaddr->row_offset = (box_dma_row_offset(src_box + i)&
>> +				MSM_BOX_SRC_ROFFSET_MASK)<<
>> +				MSM_BOX_SRC_ROFFSET_SHIFT;
>> +
>> +		if (first == 0) {
>> +			if (cmd_cnt == 1)
>> +				box_cmd_vaddr->cmd_cntrl |=
>> +				CMD_LC | CMD_OCB | CMD_OCU;
>> +			else
>> +				box_cmd_vaddr->cmd_cntrl |=
>> +						CMD_OCB;
>> +			first = 1;
>> +		}
>> +		box_cmd_vaddr++;
>> +	}
>> +
>> +	if (cmd_cnt>  1) {
>> +		box_cmd_vaddr--;
>> +		box_cmd_vaddr->cmd_cntrl |= CMD_LC | CMD_OCU;
>> +	}
>> +
>> +	box_cmd_vaddr = new->vaddr_box_cmd;
>> +
>> +	for (i = 0; i<  num_list; i++) {
>> +
>> +		box_cmd_vaddr->dst_row_addr = box_dma_row_address(dst_box + i);
>> +		box_cmd_vaddr->src_dst_len |=
>> +			(box_dma_row_len(dst_box + i)&  MSM_BOX_DST_RLEN_MASK);
>> +		box_cmd_vaddr->num_rows |=
>> +				(box_dma_row_num(dst_box + i)&
>> +			MSM_BOX_DST_RNUM_MASK);
>> +
>> +		box_cmd_vaddr->row_offset |=
>> +				(box_dma_row_offset(dst_box + i)&
>> +					MSM_BOX_DST_ROFFSET_MASK);
>> +		box_cmd_vaddr++;
>> +	}
>> +#ifdef DEBUG
>> +	i = 0;
>> +	box_cmd_vaddr = new->vaddr_box_cmd;
>> +	do {
>> +		dev_dbg(chan->dev, "cmd %d src 0x%x dst 0x%x len 0x%x "
>> +		"cntrl 0x%x row_offset 0x%x num_rows 0x%x\n",
>> +			i, box_cmd_vaddr->src_row_addr,
>> +			box_cmd_vaddr->dst_row_addr,
>> +			box_cmd_vaddr->src_dst_len,
>> +			box_cmd_vaddr->cmd_cntrl,
>> +			box_cmd_vaddr->row_offset,
>> +			box_cmd_vaddr->num_rows);
>> +			box_cmd_vaddr++;
>> +			i++;
>> +	} while (!((box_cmd_vaddr-1)->cmd_cntrl&  CMD_LC));
>> +#endif
>> +	new->async_tx.flags = flags;
>> +	new->async_tx.cookie = -EBUSY;
>> +
>> +	return&new->async_tx;
>> +}
>> +
>> +/*
>> + *  Controlling the hardware channel like stopping, flushing.
>> + */
>> +static int msm_dma_chan_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd,
>> +							unsigned long arg)
>> +{
>> +	int cmd_type = (int) arg;
>
> Why do you need to cast here? Both the flush macro's are positive.
>
>> +
>> +	if (cmd == DMA_TERMINATE_ALL) {
>> +		switch (cmd_type) {
>> +		case GRACEFUL_FLUSH:
>> +				msm_dmov_stop_cmd(chan->chan_id, NULL, 1);
>> +			break;
>> +		case FORCED_FLUSH:
>> +			/*
>> +			 * We treate default as forced flush
>> +			 * so we fall through
>> +			 */
>> +		default:
>> +				msm_dmov_stop_cmd(chan->chan_id, NULL, 0);
>> +			break;
>> +		}
>> +	}
>> +	return 0;
>> +}
>> +
>
>

I will address the comments in next patch release, i will wait for 
sometime for vinod comments and release new patch v3.

Ravi
-- 
Sent by a consultant of the Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum.
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