Re: [PATCH 3/5] sh: fix DMA driver's descriptor chaining and cookie assignment
From: Dan Williams
Date: Mon Dec 07 2009 - 19:58:12 EST
I would like an acked-by from Nobuhiro on this one.
[ full patch quoted below ]
Thanks,
Dan
On Fri, Dec 4, 2009 at 11:44 AM, Guennadi Liakhovetski
<g.liakhovetski@xxxxxx> wrote:
> The SH DMA driver wrongly assigns negative cookies to transfer descriptors,
> also, its chaining of partial descriptors is broken. The latter problem is
> usually invisible, because maximum transfer size per chunk is 16M, but if you
> artificially set this limit lower, the driver fails. Since cookies are also
> used in chunk management, both these problems are fixed in one patch.
>
> Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@xxxxxx>
> ---
> drivers/dma/shdma.c | 246 ++++++++++++++++++++++++++++++++-------------------
> drivers/dma/shdma.h | 1 -
> 2 files changed, 153 insertions(+), 94 deletions(-)
>
> diff --git a/drivers/dma/shdma.c b/drivers/dma/shdma.c
> index f5fae12..aac8f78 100644
> --- a/drivers/dma/shdma.c
> +++ b/drivers/dma/shdma.c
> @@ -30,9 +30,12 @@
> #include "shdma.h"
>
> /* DMA descriptor control */
> -#define DESC_LAST (-1)
> -#define DESC_COMP (1)
> -#define DESC_NCOMP (0)
> +enum sh_dmae_desc_status {
> + DESC_PREPARED,
> + DESC_SUBMITTED,
> + DESC_COMPLETED, /* completed, have to call callback */
> + DESC_WAITING, /* callback called, waiting for ack / re-submit */
> +};
>
> #define NR_DESCS_PER_CHANNEL 32
> /*
> @@ -45,6 +48,8 @@
> */
> #define RS_DEFAULT (RS_DUAL)
>
> +static void sh_dmae_chan_ld_cleanup(struct sh_dmae_chan *sh_chan, bool all);
> +
> #define SH_DMAC_CHAN_BASE(id) (dma_base_addr[id])
> static void sh_dmae_writel(struct sh_dmae_chan *sh_dc, u32 data, u32 reg)
> {
> @@ -185,7 +190,7 @@ static int dmae_set_dmars(struct sh_dmae_chan *sh_chan, u16 val)
>
> static dma_cookie_t sh_dmae_tx_submit(struct dma_async_tx_descriptor *tx)
> {
> - struct sh_desc *desc = tx_to_sh_desc(tx);
> + struct sh_desc *desc = tx_to_sh_desc(tx), *chunk;
> struct sh_dmae_chan *sh_chan = to_sh_chan(tx->chan);
> dma_cookie_t cookie;
>
> @@ -196,45 +201,40 @@ static dma_cookie_t sh_dmae_tx_submit(struct dma_async_tx_descriptor *tx)
> if (cookie < 0)
> cookie = 1;
>
> - /* If desc only in the case of 1 */
> - if (desc->async_tx.cookie != -EBUSY)
> - desc->async_tx.cookie = cookie;
> - sh_chan->common.cookie = desc->async_tx.cookie;
> -
> - list_splice_init(&desc->tx_list, sh_chan->ld_queue.prev);
> + tx->cookie = cookie;
> + dev_dbg(sh_chan->dev, "submit %p #%d start %u\n",
> + tx, tx->cookie, desc->hw.sar);
> + sh_chan->common.cookie = tx->cookie;
> +
> + /* Mark all chunks of this descriptor as submitted */
> + list_for_each_entry(chunk, desc->node.prev, node) {
> + /*
> + * All chunks are on the global ld_queue, so, we have to find
> + * the end of the chain ourselves
> + */
> + if (chunk != desc && (chunk->async_tx.cookie > 0 ||
> + chunk->async_tx.cookie == -EBUSY))
> + break;
> + chunk->mark = DESC_SUBMITTED;
> + }
>
> spin_unlock_bh(&sh_chan->desc_lock);
>
> return cookie;
> }
>
> +/* Called with desc_lock held */
> static struct sh_desc *sh_dmae_get_desc(struct sh_dmae_chan *sh_chan)
> {
> - struct sh_desc *desc, *_desc, *ret = NULL;
> -
> - spin_lock_bh(&sh_chan->desc_lock);
> - list_for_each_entry_safe(desc, _desc, &sh_chan->ld_free, node) {
> - if (async_tx_test_ack(&desc->async_tx)) {
> - list_del(&desc->node);
> - ret = desc;
> - break;
> - }
> - }
> - spin_unlock_bh(&sh_chan->desc_lock);
> -
> - return ret;
> -}
> + struct sh_desc *desc;
>
> -static void sh_dmae_put_desc(struct sh_dmae_chan *sh_chan, struct sh_desc *desc)
> -{
> - if (desc) {
> - spin_lock_bh(&sh_chan->desc_lock);
> + if (list_empty(&sh_chan->ld_free))
> + return NULL;
>
> - list_splice_init(&desc->tx_list, &sh_chan->ld_free);
> - list_add(&desc->node, &sh_chan->ld_free);
> + desc = list_entry(sh_chan->ld_free.next, struct sh_desc, node);
> + list_del(&desc->node);
>
> - spin_unlock_bh(&sh_chan->desc_lock);
> - }
> + return desc;
> }
>
> static int sh_dmae_alloc_chan_resources(struct dma_chan *chan)
> @@ -254,10 +254,9 @@ static int sh_dmae_alloc_chan_resources(struct dma_chan *chan)
> &sh_chan->common);
> desc->async_tx.tx_submit = sh_dmae_tx_submit;
> desc->async_tx.flags = DMA_CTRL_ACK;
> - INIT_LIST_HEAD(&desc->tx_list);
> - sh_dmae_put_desc(sh_chan, desc);
>
> spin_lock_bh(&sh_chan->desc_lock);
> + list_add(&desc->node, &sh_chan->ld_free);
> sh_chan->descs_allocated++;
> }
> spin_unlock_bh(&sh_chan->desc_lock);
> @@ -274,7 +273,10 @@ static void sh_dmae_free_chan_resources(struct dma_chan *chan)
> struct sh_desc *desc, *_desc;
> LIST_HEAD(list);
>
> - BUG_ON(!list_empty(&sh_chan->ld_queue));
> + /* Prepared and not submitted descriptors can still be on the queue */
> + if (!list_empty(&sh_chan->ld_queue))
> + sh_dmae_chan_ld_cleanup(sh_chan, true);
> +
> spin_lock_bh(&sh_chan->desc_lock);
>
> list_splice_init(&sh_chan->ld_free, &list);
> @@ -293,6 +295,7 @@ static struct dma_async_tx_descriptor *sh_dmae_prep_memcpy(
> struct sh_dmae_chan *sh_chan;
> struct sh_desc *first = NULL, *prev = NULL, *new;
> size_t copy_size;
> + LIST_HEAD(tx_list);
>
> if (!chan)
> return NULL;
> @@ -302,43 +305,70 @@ static struct dma_async_tx_descriptor *sh_dmae_prep_memcpy(
>
> sh_chan = to_sh_chan(chan);
>
> + /* Have to lock the whole loop to protect against concurrent release */
> + spin_lock_bh(&sh_chan->desc_lock);
> +
> + /*
> + * Chaining:
> + * first descriptor is what user is dealing with in all API calls, its
> + * cookie is at first set to -EBUSY, at tx-submit to a positive
> + * number
> + * if more than one chunk is needed further chunks have cookie = -EINVAL
> + * the last chunk, if not equal to the first, has cookie = -ENOSPC
> + * all chunks are linked onto the tx_list head with their .node heads
> + * only during this function, then they are immediately spliced
> + * onto the queue
> + */
> do {
> /* Allocate the link descriptor from DMA pool */
> new = sh_dmae_get_desc(sh_chan);
> if (!new) {
> dev_err(sh_chan->dev,
> "No free memory for link descriptor\n");
> - goto err_get_desc;
> + list_splice(&tx_list, &sh_chan->ld_free);
> + spin_unlock_bh(&sh_chan->desc_lock);
> + return NULL;
> }
>
> - copy_size = min(len, (size_t)SH_DMA_TCR_MAX);
> + copy_size = min(len, (size_t)SH_DMA_TCR_MAX + 1);
>
> new->hw.sar = dma_src;
> new->hw.dar = dma_dest;
> new->hw.tcr = copy_size;
> - if (!first)
> + if (!first) {
> + /* First desc */
> + new->async_tx.cookie = -EBUSY;
> first = new;
> + } else {
> + /* Other desc - invisible to the user */
> + new->async_tx.cookie = -EINVAL;
> + }
> +
> + dev_dbg(sh_chan->dev,
> + "chaining %u of %u with %p, start %u, cookie %d\n",
> + copy_size, len, &new->async_tx, dma_src,
> + new->async_tx.cookie);
>
> - new->mark = DESC_NCOMP;
> - async_tx_ack(&new->async_tx);
> + new->mark = DESC_PREPARED;
> + new->async_tx.flags = flags;
>
> prev = new;
> len -= copy_size;
> dma_src += copy_size;
> dma_dest += copy_size;
> /* Insert the link descriptor to the LD ring */
> - list_add_tail(&new->node, &first->tx_list);
> + list_add_tail(&new->node, &tx_list);
> } while (len);
>
> - new->async_tx.flags = flags; /* client is in control of this ack */
> - new->async_tx.cookie = -EBUSY; /* Last desc */
> + if (new != first)
> + new->async_tx.cookie = -ENOSPC;
>
> - return &first->async_tx;
> + /* Put them immediately on the queue, so, they don't get lost */
> + list_splice_tail(&tx_list, sh_chan->ld_queue.prev);
>
> -err_get_desc:
> - sh_dmae_put_desc(sh_chan, first);
> - return NULL;
> + spin_unlock_bh(&sh_chan->desc_lock);
>
> + return &first->async_tx;
> }
>
> /*
> @@ -346,64 +376,87 @@ err_get_desc:
> *
> * This function clean up the ld_queue of DMA channel.
> */
> -static void sh_dmae_chan_ld_cleanup(struct sh_dmae_chan *sh_chan)
> +static void sh_dmae_chan_ld_cleanup(struct sh_dmae_chan *sh_chan, bool all)
> {
> struct sh_desc *desc, *_desc;
>
> spin_lock_bh(&sh_chan->desc_lock);
> list_for_each_entry_safe(desc, _desc, &sh_chan->ld_queue, node) {
> - dma_async_tx_callback callback;
> - void *callback_param;
> + struct dma_async_tx_descriptor *tx = &desc->async_tx;
>
> - /* non send data */
> - if (desc->mark == DESC_NCOMP)
> + /* unsent data */
> + if (desc->mark == DESC_SUBMITTED && !all)
> break;
>
> - /* send data sesc */
> - callback = desc->async_tx.callback;
> - callback_param = desc->async_tx.callback_param;
> + if (desc->mark == DESC_PREPARED && !all)
> + continue;
> +
> + /* Call callback on the "exposed" descriptor (cookie > 0) */
> + if (tx->cookie > 0 && (desc->mark == DESC_COMPLETED ||
> + desc->mark == DESC_WAITING)) {
> + struct sh_desc *chunk;
> + bool head_acked = async_tx_test_ack(tx);
> + /* sent data desc */
> + dma_async_tx_callback callback = tx->callback;
> +
> + /* Run the link descriptor callback function */
> + if (callback && desc->mark == DESC_COMPLETED) {
> + spin_unlock_bh(&sh_chan->desc_lock);
> + dev_dbg(sh_chan->dev,
> + "descriptor %p callback\n", tx);
> + callback(tx->callback_param);
> + spin_lock_bh(&sh_chan->desc_lock);
> + }
>
> - /* Remove from ld_queue list */
> - list_splice_init(&desc->tx_list, &sh_chan->ld_free);
> + list_for_each_entry(chunk, desc->node.prev, node) {
> + /*
> + * All chunks are on the global ld_queue, so, we
> + * have to find the end of the chain ourselves
> + */
> + if (chunk != desc &&
> + (chunk->async_tx.cookie > 0 ||
> + chunk->async_tx.cookie == -EBUSY))
> + break;
> +
> + if (head_acked)
> + async_tx_ack(&chunk->async_tx);
> + else
> + chunk->mark = DESC_WAITING;
> + }
> + }
>
> - dev_dbg(sh_chan->dev, "link descriptor %p will be recycle.\n",
> - desc);
> + dev_dbg(sh_chan->dev, "descriptor %p #%d completed.\n",
> + tx, tx->cookie);
>
> - list_move(&desc->node, &sh_chan->ld_free);
> - /* Run the link descriptor callback function */
> - if (callback) {
> - spin_unlock_bh(&sh_chan->desc_lock);
> - dev_dbg(sh_chan->dev, "link descriptor %p callback\n",
> - desc);
> - callback(callback_param);
> - spin_lock_bh(&sh_chan->desc_lock);
> - }
> + if (((desc->mark == DESC_COMPLETED ||
> + desc->mark == DESC_WAITING) &&
> + async_tx_test_ack(&desc->async_tx)) || all)
> + /* Remove from ld_queue list */
> + list_move(&desc->node, &sh_chan->ld_free);
> }
> spin_unlock_bh(&sh_chan->desc_lock);
> }
>
> static void sh_chan_xfer_ld_queue(struct sh_dmae_chan *sh_chan)
> {
> - struct list_head *ld_node;
> struct sh_dmae_regs hw;
> + struct sh_desc *sd;
>
> /* DMA work check */
> if (dmae_is_idle(sh_chan))
> return;
>
> + spin_lock_bh(&sh_chan->desc_lock);
> /* Find the first un-transfer desciptor */
> - for (ld_node = sh_chan->ld_queue.next;
> - (ld_node != &sh_chan->ld_queue)
> - && (to_sh_desc(ld_node)->mark == DESC_COMP);
> - ld_node = ld_node->next)
> - cpu_relax();
> -
> - if (ld_node != &sh_chan->ld_queue) {
> - /* Get the ld start address from ld_queue */
> - hw = to_sh_desc(ld_node)->hw;
> - dmae_set_reg(sh_chan, hw);
> - dmae_start(sh_chan);
> - }
> + list_for_each_entry(sd, &sh_chan->ld_queue, node)
> + if (sd->mark == DESC_SUBMITTED) {
> + /* Get the ld start address from ld_queue */
> + hw = sd->hw;
> + dmae_set_reg(sh_chan, hw);
> + dmae_start(sh_chan);
> + break;
> + }
> + spin_unlock_bh(&sh_chan->desc_lock);
> }
>
> static void sh_dmae_memcpy_issue_pending(struct dma_chan *chan)
> @@ -421,12 +474,11 @@ static enum dma_status sh_dmae_is_complete(struct dma_chan *chan,
> dma_cookie_t last_used;
> dma_cookie_t last_complete;
>
> - sh_dmae_chan_ld_cleanup(sh_chan);
> + sh_dmae_chan_ld_cleanup(sh_chan, false);
>
> last_used = chan->cookie;
> last_complete = sh_chan->completed_cookie;
> - if (last_complete == -EBUSY)
> - last_complete = last_used;
> + BUG_ON(last_complete < 0);
>
> if (done)
> *done = last_complete;
> @@ -481,11 +533,13 @@ static irqreturn_t sh_dmae_err(int irq, void *data)
> err = sh_dmae_rst(0);
> if (err)
> return err;
> +#ifdef SH_DMAC_BASE1
> if (shdev->pdata.mode & SHDMA_DMAOR1) {
> err = sh_dmae_rst(1);
> if (err)
> return err;
> }
> +#endif
> disable_irq(irq);
> return IRQ_HANDLED;
> }
> @@ -499,30 +553,36 @@ static void dmae_do_tasklet(unsigned long data)
> u32 sar_buf = sh_dmae_readl(sh_chan, SAR);
> list_for_each_entry_safe(desc, _desc,
> &sh_chan->ld_queue, node) {
> - if ((desc->hw.sar + desc->hw.tcr) == sar_buf) {
> + if ((desc->hw.sar + desc->hw.tcr) == sar_buf &&
> + desc->mark == DESC_SUBMITTED) {
> cur_desc = desc;
> break;
> }
> }
>
> if (cur_desc) {
> + dev_dbg(sh_chan->dev, "done %p #%d start %u\n",
> + &cur_desc->async_tx, cur_desc->async_tx.cookie,
> + cur_desc->hw.sar);
> +
> switch (cur_desc->async_tx.cookie) {
> - case 0: /* other desc data */
> + case -EINVAL:
> + case -ENOSPC:
> + /* other desc data */
> break;
> - case -EBUSY: /* last desc */
> - sh_chan->completed_cookie =
> - cur_desc->async_tx.cookie;
> + case -EBUSY: /* Cannot be */
> + BUG_ON(1);
> break;
> - default: /* first desc ( 0 < )*/
> + default: /* first desc: cookie > 0 */
> sh_chan->completed_cookie =
> - cur_desc->async_tx.cookie - 1;
> + cur_desc->async_tx.cookie;
> break;
> }
> - cur_desc->mark = DESC_COMP;
> + cur_desc->mark = DESC_COMPLETED;
> }
> /* Next desc */
> sh_chan_xfer_ld_queue(sh_chan);
> - sh_dmae_chan_ld_cleanup(sh_chan);
> + sh_dmae_chan_ld_cleanup(sh_chan, false);
> }
>
> static unsigned int get_dmae_irq(unsigned int id)
> diff --git a/drivers/dma/shdma.h b/drivers/dma/shdma.h
> index 2b4bc15..c93555c 100644
> --- a/drivers/dma/shdma.h
> +++ b/drivers/dma/shdma.h
> @@ -26,7 +26,6 @@ struct sh_dmae_regs {
> };
>
> struct sh_desc {
> - struct list_head tx_list;
> struct sh_dmae_regs hw;
> struct list_head node;
> struct dma_async_tx_descriptor async_tx;
> --
> 1.6.2.4
>
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