Re: [PATCH 01/15] iio: buffer-dma: Get rid of incoming/outgoing queues
Le lun., nov. 22 2021 at 16:17:59 +0100, Lars-Peter Clausen
a écrit :
On 11/22/21 4:16 PM, Paul Cercueil wrote:
Hi Lars,
Le lun., nov. 22 2021 at 16:08:51 +0100, Lars-Peter Clausen
a écrit :
On 11/21/21 9:08 PM, Paul Cercueil wrote:
Le dim., nov. 21 2021 at 19:49:03 +0100, Lars-Peter Clausen
a écrit :
On 11/21/21 6:52 PM, Paul Cercueil wrote:
Hi Lars,
Le dim., nov. 21 2021 at 17:23:35 +0100, Lars-Peter Clausen
a écrit :
On 11/15/21 3:19 PM, Paul Cercueil wrote:
The buffer-dma code was using two queues, incoming and
outgoing, to
manage the state of the blocks in use.
While this totally works, it adds some complexity to the code,
especially since the code only manages 2 blocks. It is much
easier to
just check each block's state manually, and keep a counter for
the next
block to dequeue.
Since the new DMABUF based API wouldn't use these incoming and
outgoing
queues anyway, getting rid of them now makes the upcoming
changes
simpler.
Signed-off-by: Paul Cercueil
The outgoing queue is going to be replaced by fences, but I
think we need to keep the incoming queue.
Blocks are always accessed in sequential order, so we now have a
"queue->next_dequeue" that cycles between the buffers
allocated for fileio.
[...]
@@ -442,28 +435,33 @@
EXPORT_SYMBOL_GPL(iio_dma_buffer_disable);
static void iio_dma_buffer_enqueue(struct
iio_dma_buffer_queue *queue,
struct iio_dma_buffer_block *block)
{
-if (block->state == IIO_BLOCK_STATE_DEAD) {
+if (block->state == IIO_BLOCK_STATE_DEAD)
iio_buffer_block_put(block);
-} else if (queue->active) {
+else if (queue->active)
iio_dma_buffer_submit_block(queue, block);
-} else {
+else
block->state = IIO_BLOCK_STATE_QUEUED;
-list_add_tail(>head, >incoming);
If iio_dma_buffer_enqueue() is called with a dmabuf and the
buffer is not active, it will be marked as queued,
but we don't actually keep a reference to it
anywhere. It will never be submitted to the DMA, and
it will never be signaled as completed.
We do keep a reference to the buffers, in the
queue->fileio.blocks array. When the buffer is enabled,
all the blocks in that array that are in the "queued"
state will be submitted to the DMA.
But not when used in combination with the DMA buf changes later
in this series.
That's still the case after the DMABUF changes of the series. Or
can you point me exactly what you think is broken?
When you allocate a DMABUF with the allocate IOCTL and then submit
it with the enqueue IOCTL before the buffer is enabled it will
end up marked as queued, but not actually be queued anywhere.
Ok, it works for me because I never enqueue blocks before enabling
the buffer. I can add a requirement that blocks must be enqueued
only after the buffer is enabled.
I don't think that is a good idea. This way you are going to
potentially drop data at the begining of your stream when the DMA
isn't ready yet.
You wouldn't drop data, but it could cause an underrun, yes. Is it such
a big deal, knowing that the buffer was just enabled? I don't think you
can disable then enable the buffer without causing a discontinuity in
the stream.
-Paul
Re: [PATCH 01/15] iio: buffer-dma: Get rid of incoming/outgoing queues
On 11/22/21 4:16 PM, Paul Cercueil wrote:
Hi Lars,
Le lun., nov. 22 2021 at 16:08:51 +0100, Lars-Peter Clausen
a écrit :
On 11/21/21 9:08 PM, Paul Cercueil wrote:
Le dim., nov. 21 2021 at 19:49:03 +0100, Lars-Peter Clausen
a écrit :
On 11/21/21 6:52 PM, Paul Cercueil wrote:
Hi Lars,
Le dim., nov. 21 2021 at 17:23:35 +0100, Lars-Peter Clausen
a écrit :
On 11/15/21 3:19 PM, Paul Cercueil wrote:
The buffer-dma code was using two queues, incoming and outgoing, to
manage the state of the blocks in use.
While this totally works, it adds some complexity to the code,
especially since the code only manages 2 blocks. It is much
easier to
just check each block's state manually, and keep a counter for
the next
block to dequeue.
Since the new DMABUF based API wouldn't use these incoming and
outgoing
queues anyway, getting rid of them now makes the upcoming changes
simpler.
Signed-off-by: Paul Cercueil
The outgoing queue is going to be replaced by fences, but I think
we need to keep the incoming queue.
Blocks are always accessed in sequential order, so we now have a
"queue->next_dequeue" that cycles between the buffers
allocated for fileio.
[...]
@@ -442,28 +435,33 @@ EXPORT_SYMBOL_GPL(iio_dma_buffer_disable);
static void iio_dma_buffer_enqueue(struct iio_dma_buffer_queue
*queue,
struct iio_dma_buffer_block *block)
{
- if (block->state == IIO_BLOCK_STATE_DEAD) {
+ if (block->state == IIO_BLOCK_STATE_DEAD)
iio_buffer_block_put(block);
- } else if (queue->active) {
+ else if (queue->active)
iio_dma_buffer_submit_block(queue, block);
- } else {
+ else
block->state = IIO_BLOCK_STATE_QUEUED;
- list_add_tail(>head, >incoming);
If iio_dma_buffer_enqueue() is called with a dmabuf and the
buffer is not active, it will be marked as queued, but we
don't actually keep a reference to it anywhere. It will
never be submitted to the DMA, and it will never be
signaled as completed.
We do keep a reference to the buffers, in the queue->fileio.blocks
array. When the buffer is enabled, all the blocks in that
array that are in the "queued" state will be submitted to the
DMA.
But not when used in combination with the DMA buf changes later in
this series.
That's still the case after the DMABUF changes of the series. Or can
you point me exactly what you think is broken?
When you allocate a DMABUF with the allocate IOCTL and then submit it
with the enqueue IOCTL before the buffer is enabled it will end up
marked as queued, but not actually be queued anywhere.
Ok, it works for me because I never enqueue blocks before enabling the
buffer. I can add a requirement that blocks must be enqueued only
after the buffer is enabled.
I don't think that is a good idea. This way you are going to potentially
drop data at the begining of your stream when the DMA isn't ready yet.
Re: [PATCH 01/15] iio: buffer-dma: Get rid of incoming/outgoing queues
Hi Lars,
Le lun., nov. 22 2021 at 16:08:51 +0100, Lars-Peter Clausen
a écrit :
On 11/21/21 9:08 PM, Paul Cercueil wrote:
Le dim., nov. 21 2021 at 19:49:03 +0100, Lars-Peter Clausen
a écrit :
On 11/21/21 6:52 PM, Paul Cercueil wrote:
Hi Lars,
Le dim., nov. 21 2021 at 17:23:35 +0100, Lars-Peter Clausen
a écrit :
On 11/15/21 3:19 PM, Paul Cercueil wrote:
The buffer-dma code was using two queues, incoming and outgoing,
to
manage the state of the blocks in use.
While this totally works, it adds some complexity to the code,
especially since the code only manages 2 blocks. It is much
easier to
just check each block's state manually, and keep a counter for
the next
block to dequeue.
Since the new DMABUF based API wouldn't use these incoming and
outgoing
queues anyway, getting rid of them now makes the upcoming changes
simpler.
Signed-off-by: Paul Cercueil
The outgoing queue is going to be replaced by fences, but I think
we need to keep the incoming queue.
Blocks are always accessed in sequential order, so we now have a
"queue->next_dequeue" that cycles between the buffers
allocated for fileio.
[...]
@@ -442,28 +435,33 @@ EXPORT_SYMBOL_GPL(iio_dma_buffer_disable);
static void iio_dma_buffer_enqueue(struct iio_dma_buffer_queue
*queue,
struct iio_dma_buffer_block *block)
{
-if (block->state == IIO_BLOCK_STATE_DEAD) {
+if (block->state == IIO_BLOCK_STATE_DEAD)
iio_buffer_block_put(block);
-} else if (queue->active) {
+else if (queue->active)
iio_dma_buffer_submit_block(queue, block);
-} else {
+else
block->state = IIO_BLOCK_STATE_QUEUED;
-list_add_tail(>head, >incoming);
If iio_dma_buffer_enqueue() is called with a dmabuf and the
buffer is not active, it will be marked as queued, but we
don't actually keep a reference to it anywhere. It will
never be submitted to the DMA, and it will never be
signaled as completed.
We do keep a reference to the buffers, in the queue->fileio.blocks
array. When the buffer is enabled, all the blocks in that
array that are in the "queued" state will be submitted to the
DMA.
But not when used in combination with the DMA buf changes later in
this series.
That's still the case after the DMABUF changes of the series. Or can
you point me exactly what you think is broken?
When you allocate a DMABUF with the allocate IOCTL and then submit it
with the enqueue IOCTL before the buffer is enabled it will end up
marked as queued, but not actually be queued anywhere.
Ok, it works for me because I never enqueue blocks before enabling the
buffer. I can add a requirement that blocks must be enqueued only after
the buffer is enabled.
Cheers,
-Paul
Re: [PATCH 01/15] iio: buffer-dma: Get rid of incoming/outgoing queues
On 11/21/21 9:08 PM, Paul Cercueil wrote:
Le dim., nov. 21 2021 at 19:49:03 +0100, Lars-Peter Clausen
a écrit :
On 11/21/21 6:52 PM, Paul Cercueil wrote:
Hi Lars,
Le dim., nov. 21 2021 at 17:23:35 +0100, Lars-Peter Clausen
a écrit :
On 11/15/21 3:19 PM, Paul Cercueil wrote:
The buffer-dma code was using two queues, incoming and outgoing, to
manage the state of the blocks in use.
While this totally works, it adds some complexity to the code,
especially since the code only manages 2 blocks. It is much easier to
just check each block's state manually, and keep a counter for the
next
block to dequeue.
Since the new DMABUF based API wouldn't use these incoming and
outgoing
queues anyway, getting rid of them now makes the upcoming changes
simpler.
Signed-off-by: Paul Cercueil
The outgoing queue is going to be replaced by fences, but I think
we need to keep the incoming queue.
Blocks are always accessed in sequential order, so we now have a
"queue->next_dequeue" that cycles between the buffers allocated for
fileio.
[...]
@@ -442,28 +435,33 @@ EXPORT_SYMBOL_GPL(iio_dma_buffer_disable);
static void iio_dma_buffer_enqueue(struct iio_dma_buffer_queue
*queue,
struct iio_dma_buffer_block *block)
{
- if (block->state == IIO_BLOCK_STATE_DEAD) {
+ if (block->state == IIO_BLOCK_STATE_DEAD)
iio_buffer_block_put(block);
- } else if (queue->active) {
+ else if (queue->active)
iio_dma_buffer_submit_block(queue, block);
- } else {
+ else
block->state = IIO_BLOCK_STATE_QUEUED;
- list_add_tail(>head, >incoming);
If iio_dma_buffer_enqueue() is called with a dmabuf and the buffer
is not active, it will be marked as queued, but we don't actually
keep a reference to it anywhere. It will never be submitted to
the DMA, and it will never be signaled as completed.
We do keep a reference to the buffers, in the queue->fileio.blocks
array. When the buffer is enabled, all the blocks in that array
that are in the "queued" state will be submitted to the DMA.
But not when used in combination with the DMA buf changes later in
this series.
That's still the case after the DMABUF changes of the series. Or can
you point me exactly what you think is broken?
When you allocate a DMABUF with the allocate IOCTL and then submit it
with the enqueue IOCTL before the buffer is enabled it will end up
marked as queued, but not actually be queued anywhere.
Re: [PATCH 01/15] iio: buffer-dma: Get rid of incoming/outgoing queues
Le dim., nov. 21 2021 at 19:49:03 +0100, Lars-Peter Clausen
a écrit :
On 11/21/21 6:52 PM, Paul Cercueil wrote:
Hi Lars,
Le dim., nov. 21 2021 at 17:23:35 +0100, Lars-Peter Clausen
a écrit :
On 11/15/21 3:19 PM, Paul Cercueil wrote:
The buffer-dma code was using two queues, incoming and outgoing, to
manage the state of the blocks in use.
While this totally works, it adds some complexity to the code,
especially since the code only manages 2 blocks. It is much easier
to
just check each block's state manually, and keep a counter for the
next
block to dequeue.
Since the new DMABUF based API wouldn't use these incoming and
outgoing
queues anyway, getting rid of them now makes the upcoming changes
simpler.
Signed-off-by: Paul Cercueil
The outgoing queue is going to be replaced by fences, but I think
we need to keep the incoming queue.
Blocks are always accessed in sequential order, so we now have a
"queue->next_dequeue" that cycles between the buffers allocated for
fileio.
[...]
@@ -442,28 +435,33 @@ EXPORT_SYMBOL_GPL(iio_dma_buffer_disable);
static void iio_dma_buffer_enqueue(struct iio_dma_buffer_queue
*queue,
struct iio_dma_buffer_block *block)
{
-if (block->state == IIO_BLOCK_STATE_DEAD) {
+if (block->state == IIO_BLOCK_STATE_DEAD)
iio_buffer_block_put(block);
-} else if (queue->active) {
+else if (queue->active)
iio_dma_buffer_submit_block(queue, block);
-} else {
+else
block->state = IIO_BLOCK_STATE_QUEUED;
-list_add_tail(>head, >incoming);
If iio_dma_buffer_enqueue() is called with a dmabuf and the buffer
is not active, it will be marked as queued, but we don't actually
keep a reference to it anywhere. It will never be submitted to
the DMA, and it will never be signaled as completed.
We do keep a reference to the buffers, in the queue->fileio.blocks
array. When the buffer is enabled, all the blocks in that array
that are in the "queued" state will be submitted to the DMA.
But not when used in combination with the DMA buf changes later in
this series.
That's still the case after the DMABUF changes of the series. Or can
you point me exactly what you think is broken?
-Paul
Re: [PATCH 01/15] iio: buffer-dma: Get rid of incoming/outgoing queues
On 11/21/21 6:52 PM, Paul Cercueil wrote:
Hi Lars,
Le dim., nov. 21 2021 at 17:23:35 +0100, Lars-Peter Clausen
a écrit :
On 11/15/21 3:19 PM, Paul Cercueil wrote:
The buffer-dma code was using two queues, incoming and outgoing, to
manage the state of the blocks in use.
While this totally works, it adds some complexity to the code,
especially since the code only manages 2 blocks. It is much easier to
just check each block's state manually, and keep a counter for the next
block to dequeue.
Since the new DMABUF based API wouldn't use these incoming and outgoing
queues anyway, getting rid of them now makes the upcoming changes
simpler.
Signed-off-by: Paul Cercueil
The outgoing queue is going to be replaced by fences, but I think we
need to keep the incoming queue.
Blocks are always accessed in sequential order, so we now have a
"queue->next_dequeue" that cycles between the buffers allocated for
fileio.
[...]
@@ -442,28 +435,33 @@ EXPORT_SYMBOL_GPL(iio_dma_buffer_disable);
static void iio_dma_buffer_enqueue(struct iio_dma_buffer_queue
*queue,
struct iio_dma_buffer_block *block)
{
- if (block->state == IIO_BLOCK_STATE_DEAD) {
+ if (block->state == IIO_BLOCK_STATE_DEAD)
iio_buffer_block_put(block);
- } else if (queue->active) {
+ else if (queue->active)
iio_dma_buffer_submit_block(queue, block);
- } else {
+ else
block->state = IIO_BLOCK_STATE_QUEUED;
- list_add_tail(>head, >incoming);
If iio_dma_buffer_enqueue() is called with a dmabuf and the buffer is
not active, it will be marked as queued, but we don't actually keep a
reference to it anywhere. It will never be submitted to the DMA, and
it will never be signaled as completed.
We do keep a reference to the buffers, in the queue->fileio.blocks
array. When the buffer is enabled, all the blocks in that array that
are in the "queued" state will be submitted to the DMA.
But not when used in combination with the DMA buf changes later in this
series.
Re: [PATCH 01/15] iio: buffer-dma: Get rid of incoming/outgoing queues
Hi Lars,
Le dim., nov. 21 2021 at 17:23:35 +0100, Lars-Peter Clausen
a écrit :
On 11/15/21 3:19 PM, Paul Cercueil wrote:
The buffer-dma code was using two queues, incoming and outgoing, to
manage the state of the blocks in use.
While this totally works, it adds some complexity to the code,
especially since the code only manages 2 blocks. It is much easier to
just check each block's state manually, and keep a counter for the
next
block to dequeue.
Since the new DMABUF based API wouldn't use these incoming and
outgoing
queues anyway, getting rid of them now makes the upcoming changes
simpler.
Signed-off-by: Paul Cercueil
The outgoing queue is going to be replaced by fences, but I think we
need to keep the incoming queue.
Blocks are always accessed in sequential order, so we now have a
"queue->next_dequeue" that cycles between the buffers allocated for
fileio.
[...]
@@ -442,28 +435,33 @@ EXPORT_SYMBOL_GPL(iio_dma_buffer_disable);
static void iio_dma_buffer_enqueue(struct iio_dma_buffer_queue
*queue,
struct iio_dma_buffer_block *block)
{
- if (block->state == IIO_BLOCK_STATE_DEAD) {
+ if (block->state == IIO_BLOCK_STATE_DEAD)
iio_buffer_block_put(block);
- } else if (queue->active) {
+ else if (queue->active)
iio_dma_buffer_submit_block(queue, block);
- } else {
+ else
block->state = IIO_BLOCK_STATE_QUEUED;
- list_add_tail(>head, >incoming);
If iio_dma_buffer_enqueue() is called with a dmabuf and the buffer is
not active, it will be marked as queued, but we don't actually keep a
reference to it anywhere. It will never be submitted to the DMA, and
it will never be signaled as completed.
We do keep a reference to the buffers, in the queue->fileio.blocks
array. When the buffer is enabled, all the blocks in that array that
are in the "queued" state will be submitted to the DMA.
Cheers,
-Paul
Re: [PATCH 01/15] iio: buffer-dma: Get rid of incoming/outgoing queues
On 11/15/21 3:19 PM, Paul Cercueil wrote:
The buffer-dma code was using two queues, incoming and outgoing, to
manage the state of the blocks in use.
While this totally works, it adds some complexity to the code,
especially since the code only manages 2 blocks. It is much easier to
just check each block's state manually, and keep a counter for the next
block to dequeue.
Since the new DMABUF based API wouldn't use these incoming and outgoing
queues anyway, getting rid of them now makes the upcoming changes
simpler.
Signed-off-by: Paul Cercueil
The outgoing queue is going to be replaced by fences, but I think we
need to keep the incoming queue.
[...]
@@ -442,28 +435,33 @@ EXPORT_SYMBOL_GPL(iio_dma_buffer_disable);
static void iio_dma_buffer_enqueue(struct iio_dma_buffer_queue *queue,
struct iio_dma_buffer_block *block)
{
- if (block->state == IIO_BLOCK_STATE_DEAD) {
+ if (block->state == IIO_BLOCK_STATE_DEAD)
iio_buffer_block_put(block);
- } else if (queue->active) {
+ else if (queue->active)
iio_dma_buffer_submit_block(queue, block);
- } else {
+ else
block->state = IIO_BLOCK_STATE_QUEUED;
- list_add_tail(>head, >incoming);
If iio_dma_buffer_enqueue() is called with a dmabuf and the buffer is
not active, it will be marked as queued, but we don't actually keep a
reference to it anywhere. It will never be submitted to the DMA, and it
will never be signaled as completed.
Re: [PATCH 01/15] iio: buffer-dma: Get rid of incoming/outgoing queues
On Mon, 15 Nov 2021 14:19:11 +
Paul Cercueil wrote:
> The buffer-dma code was using two queues, incoming and outgoing, to
> manage the state of the blocks in use.
>
> While this totally works, it adds some complexity to the code,
> especially since the code only manages 2 blocks. It is much easier to
> just check each block's state manually, and keep a counter for the next
> block to dequeue.
>
> Since the new DMABUF based API wouldn't use these incoming and outgoing
> queues anyway, getting rid of them now makes the upcoming changes
> simpler.
>
> Signed-off-by: Paul Cercueil
This looks to be a nice little cleanup on it's own.
Let me know if you'd like me to pick this up before the main discussion
comes to any conclusion.
Jonathan
> ---
> drivers/iio/buffer/industrialio-buffer-dma.c | 68 ++--
> include/linux/iio/buffer-dma.h | 7 +-
> 2 files changed, 37 insertions(+), 38 deletions(-)
>
> diff --git a/drivers/iio/buffer/industrialio-buffer-dma.c
> b/drivers/iio/buffer/industrialio-buffer-dma.c
> index d348af8b9705..abac88f20104 100644
> --- a/drivers/iio/buffer/industrialio-buffer-dma.c
> +++ b/drivers/iio/buffer/industrialio-buffer-dma.c
> @@ -191,16 +191,8 @@ static struct iio_dma_buffer_block
> *iio_dma_buffer_alloc_block(
>
> static void _iio_dma_buffer_block_done(struct iio_dma_buffer_block *block)
> {
> - struct iio_dma_buffer_queue *queue = block->queue;
> -
> - /*
> - * The buffer has already been freed by the application, just drop the
> - * reference.
> - */
> - if (block->state != IIO_BLOCK_STATE_DEAD) {
> + if (block->state != IIO_BLOCK_STATE_DEAD)
> block->state = IIO_BLOCK_STATE_DONE;
> - list_add_tail(>head, >outgoing);
> - }
> }
>
> /**
> @@ -317,11 +309,8 @@ int iio_dma_buffer_request_update(struct iio_buffer
> *buffer)
>* dead. This means we can reset the lists without having to fear
>* corrution.
>*/
> - INIT_LIST_HEAD(>outgoing);
> spin_unlock_irq(>list_lock);
>
> - INIT_LIST_HEAD(>incoming);
> -
> for (i = 0; i < ARRAY_SIZE(queue->fileio.blocks); i++) {
> if (queue->fileio.blocks[i]) {
> block = queue->fileio.blocks[i];
> @@ -346,7 +335,6 @@ int iio_dma_buffer_request_update(struct iio_buffer
> *buffer)
> }
>
> block->state = IIO_BLOCK_STATE_QUEUED;
> - list_add_tail(>head, >incoming);
> }
>
> out_unlock:
> @@ -401,13 +389,18 @@ int iio_dma_buffer_enable(struct iio_buffer *buffer,
> struct iio_dev *indio_dev)
> {
> struct iio_dma_buffer_queue *queue = iio_buffer_to_queue(buffer);
> - struct iio_dma_buffer_block *block, *_block;
> + struct iio_dma_buffer_block *block;
> + unsigned int i;
>
> mutex_lock(>lock);
> queue->active = true;
> - list_for_each_entry_safe(block, _block, >incoming, head) {
> - list_del(>head);
> - iio_dma_buffer_submit_block(queue, block);
> + queue->fileio.next_dequeue = 0;
> +
> + for (i = 0; i < ARRAY_SIZE(queue->fileio.blocks); i++) {
> + block = queue->fileio.blocks[i];
> +
> + if (block->state == IIO_BLOCK_STATE_QUEUED)
> + iio_dma_buffer_submit_block(queue, block);
> }
> mutex_unlock(>lock);
>
> @@ -442,28 +435,33 @@ EXPORT_SYMBOL_GPL(iio_dma_buffer_disable);
> static void iio_dma_buffer_enqueue(struct iio_dma_buffer_queue *queue,
> struct iio_dma_buffer_block *block)
> {
> - if (block->state == IIO_BLOCK_STATE_DEAD) {
> + if (block->state == IIO_BLOCK_STATE_DEAD)
> iio_buffer_block_put(block);
> - } else if (queue->active) {
> + else if (queue->active)
> iio_dma_buffer_submit_block(queue, block);
> - } else {
> + else
> block->state = IIO_BLOCK_STATE_QUEUED;
> - list_add_tail(>head, >incoming);
> - }
> }
>
> static struct iio_dma_buffer_block *iio_dma_buffer_dequeue(
> struct iio_dma_buffer_queue *queue)
> {
> struct iio_dma_buffer_block *block;
> + unsigned int idx;
>
> spin_lock_irq(>list_lock);
> - block = list_first_entry_or_null(>outgoing, struct
> - iio_dma_buffer_block, head);
> - if (block != NULL) {
> - list_del(>head);
> +
> + idx = queue->fileio.next_dequeue;
> + block = queue->fileio.blocks[idx];
> +
> + if (block->state == IIO_BLOCK_STATE_DONE) {
> block->state = IIO_BLOCK_STATE_DEQUEUED;
> + idx = (idx + 1) % ARRAY_SIZE(queue->fileio.blocks);
> + queue->fileio.next_dequeue = idx;
> + } else {
> + block = NULL;
> }
> +
> spin_unlock_irq(>list_lock);
>
> return block;
> @@ -539,6 +537,7 @@ size_t iio_dma_buffer_data_available(struct iio_buffer
> *buf)
> struct iio_dma_buffer_queue *queue = iio_buffer_to_queue(buf);
>
Re: [PATCH 01/15] iio: buffer-dma: Get rid of incoming/outgoing queues
On Mon, Nov 15, 2021 at 4:19 PM Paul Cercueil wrote:
>
> The buffer-dma code was using two queues, incoming and outgoing, to
> manage the state of the blocks in use.
>
> While this totally works, it adds some complexity to the code,
> especially since the code only manages 2 blocks. It is much easier to
> just check each block's state manually, and keep a counter for the next
> block to dequeue.
>
> Since the new DMABUF based API wouldn't use these incoming and outgoing
> queues anyway, getting rid of them now makes the upcoming changes
> simpler.
>
Reviewed-by: Alexandru Ardelean
> Signed-off-by: Paul Cercueil
> ---
> drivers/iio/buffer/industrialio-buffer-dma.c | 68 ++--
> include/linux/iio/buffer-dma.h | 7 +-
> 2 files changed, 37 insertions(+), 38 deletions(-)
>
> diff --git a/drivers/iio/buffer/industrialio-buffer-dma.c
> b/drivers/iio/buffer/industrialio-buffer-dma.c
> index d348af8b9705..abac88f20104 100644
> --- a/drivers/iio/buffer/industrialio-buffer-dma.c
> +++ b/drivers/iio/buffer/industrialio-buffer-dma.c
> @@ -191,16 +191,8 @@ static struct iio_dma_buffer_block
> *iio_dma_buffer_alloc_block(
>
> static void _iio_dma_buffer_block_done(struct iio_dma_buffer_block *block)
> {
> - struct iio_dma_buffer_queue *queue = block->queue;
> -
> - /*
> -* The buffer has already been freed by the application, just drop the
> -* reference.
> -*/
> - if (block->state != IIO_BLOCK_STATE_DEAD) {
> + if (block->state != IIO_BLOCK_STATE_DEAD)
> block->state = IIO_BLOCK_STATE_DONE;
> - list_add_tail(>head, >outgoing);
> - }
> }
>
> /**
> @@ -317,11 +309,8 @@ int iio_dma_buffer_request_update(struct iio_buffer
> *buffer)
> * dead. This means we can reset the lists without having to fear
> * corrution.
> */
> - INIT_LIST_HEAD(>outgoing);
> spin_unlock_irq(>list_lock);
>
> - INIT_LIST_HEAD(>incoming);
> -
> for (i = 0; i < ARRAY_SIZE(queue->fileio.blocks); i++) {
> if (queue->fileio.blocks[i]) {
> block = queue->fileio.blocks[i];
> @@ -346,7 +335,6 @@ int iio_dma_buffer_request_update(struct iio_buffer
> *buffer)
> }
>
> block->state = IIO_BLOCK_STATE_QUEUED;
> - list_add_tail(>head, >incoming);
> }
>
> out_unlock:
> @@ -401,13 +389,18 @@ int iio_dma_buffer_enable(struct iio_buffer *buffer,
> struct iio_dev *indio_dev)
> {
> struct iio_dma_buffer_queue *queue = iio_buffer_to_queue(buffer);
> - struct iio_dma_buffer_block *block, *_block;
> + struct iio_dma_buffer_block *block;
> + unsigned int i;
>
> mutex_lock(>lock);
> queue->active = true;
> - list_for_each_entry_safe(block, _block, >incoming, head) {
> - list_del(>head);
> - iio_dma_buffer_submit_block(queue, block);
> + queue->fileio.next_dequeue = 0;
> +
> + for (i = 0; i < ARRAY_SIZE(queue->fileio.blocks); i++) {
> + block = queue->fileio.blocks[i];
> +
> + if (block->state == IIO_BLOCK_STATE_QUEUED)
> + iio_dma_buffer_submit_block(queue, block);
> }
> mutex_unlock(>lock);
>
> @@ -442,28 +435,33 @@ EXPORT_SYMBOL_GPL(iio_dma_buffer_disable);
> static void iio_dma_buffer_enqueue(struct iio_dma_buffer_queue *queue,
> struct iio_dma_buffer_block *block)
> {
> - if (block->state == IIO_BLOCK_STATE_DEAD) {
> + if (block->state == IIO_BLOCK_STATE_DEAD)
> iio_buffer_block_put(block);
> - } else if (queue->active) {
> + else if (queue->active)
> iio_dma_buffer_submit_block(queue, block);
> - } else {
> + else
> block->state = IIO_BLOCK_STATE_QUEUED;
> - list_add_tail(>head, >incoming);
> - }
> }
>
> static struct iio_dma_buffer_block *iio_dma_buffer_dequeue(
> struct iio_dma_buffer_queue *queue)
> {
> struct iio_dma_buffer_block *block;
> + unsigned int idx;
>
> spin_lock_irq(>list_lock);
> - block = list_first_entry_or_null(>outgoing, struct
> - iio_dma_buffer_block, head);
> - if (block != NULL) {
> - list_del(>head);
> +
> + idx = queue->fileio.next_dequeue;
> + block = queue->fileio.blocks[idx];
> +
> + if (block->state == IIO_BLOCK_STATE_DONE) {
> block->state = IIO_BLOCK_STATE_DEQUEUED;
> + idx = (idx + 1) % ARRAY_SIZE(queue->fileio.blocks);
> + queue->fileio.next_dequeue = idx;
> + } else {
> + block = NULL;
> }
> +
> spin_unlock_irq(>list_lock);
>
> return block;
> @@ -539,6 +537,7 @@ size_t iio_dma_buffer_data_available(struct iio_buffer
> *buf)
> struct iio_dma_buffer_queue *queue = iio_buffer_to_queue(buf);
> struct
[PATCH 01/15] iio: buffer-dma: Get rid of incoming/outgoing queues
The buffer-dma code was using two queues, incoming and outgoing, to
manage the state of the blocks in use.
While this totally works, it adds some complexity to the code,
especially since the code only manages 2 blocks. It is much easier to
just check each block's state manually, and keep a counter for the next
block to dequeue.
Since the new DMABUF based API wouldn't use these incoming and outgoing
queues anyway, getting rid of them now makes the upcoming changes
simpler.
Signed-off-by: Paul Cercueil
---
drivers/iio/buffer/industrialio-buffer-dma.c | 68 ++--
include/linux/iio/buffer-dma.h | 7 +-
2 files changed, 37 insertions(+), 38 deletions(-)
diff --git a/drivers/iio/buffer/industrialio-buffer-dma.c
b/drivers/iio/buffer/industrialio-buffer-dma.c
index d348af8b9705..abac88f20104 100644
--- a/drivers/iio/buffer/industrialio-buffer-dma.c
+++ b/drivers/iio/buffer/industrialio-buffer-dma.c
@@ -191,16 +191,8 @@ static struct iio_dma_buffer_block
*iio_dma_buffer_alloc_block(
static void _iio_dma_buffer_block_done(struct iio_dma_buffer_block *block)
{
- struct iio_dma_buffer_queue *queue = block->queue;
-
- /*
-* The buffer has already been freed by the application, just drop the
-* reference.
-*/
- if (block->state != IIO_BLOCK_STATE_DEAD) {
+ if (block->state != IIO_BLOCK_STATE_DEAD)
block->state = IIO_BLOCK_STATE_DONE;
- list_add_tail(>head, >outgoing);
- }
}
/**
@@ -317,11 +309,8 @@ int iio_dma_buffer_request_update(struct iio_buffer
*buffer)
* dead. This means we can reset the lists without having to fear
* corrution.
*/
- INIT_LIST_HEAD(>outgoing);
spin_unlock_irq(>list_lock);
- INIT_LIST_HEAD(>incoming);
-
for (i = 0; i < ARRAY_SIZE(queue->fileio.blocks); i++) {
if (queue->fileio.blocks[i]) {
block = queue->fileio.blocks[i];
@@ -346,7 +335,6 @@ int iio_dma_buffer_request_update(struct iio_buffer *buffer)
}
block->state = IIO_BLOCK_STATE_QUEUED;
- list_add_tail(>head, >incoming);
}
out_unlock:
@@ -401,13 +389,18 @@ int iio_dma_buffer_enable(struct iio_buffer *buffer,
struct iio_dev *indio_dev)
{
struct iio_dma_buffer_queue *queue = iio_buffer_to_queue(buffer);
- struct iio_dma_buffer_block *block, *_block;
+ struct iio_dma_buffer_block *block;
+ unsigned int i;
mutex_lock(>lock);
queue->active = true;
- list_for_each_entry_safe(block, _block, >incoming, head) {
- list_del(>head);
- iio_dma_buffer_submit_block(queue, block);
+ queue->fileio.next_dequeue = 0;
+
+ for (i = 0; i < ARRAY_SIZE(queue->fileio.blocks); i++) {
+ block = queue->fileio.blocks[i];
+
+ if (block->state == IIO_BLOCK_STATE_QUEUED)
+ iio_dma_buffer_submit_block(queue, block);
}
mutex_unlock(>lock);
@@ -442,28 +435,33 @@ EXPORT_SYMBOL_GPL(iio_dma_buffer_disable);
static void iio_dma_buffer_enqueue(struct iio_dma_buffer_queue *queue,
struct iio_dma_buffer_block *block)
{
- if (block->state == IIO_BLOCK_STATE_DEAD) {
+ if (block->state == IIO_BLOCK_STATE_DEAD)
iio_buffer_block_put(block);
- } else if (queue->active) {
+ else if (queue->active)
iio_dma_buffer_submit_block(queue, block);
- } else {
+ else
block->state = IIO_BLOCK_STATE_QUEUED;
- list_add_tail(>head, >incoming);
- }
}
static struct iio_dma_buffer_block *iio_dma_buffer_dequeue(
struct iio_dma_buffer_queue *queue)
{
struct iio_dma_buffer_block *block;
+ unsigned int idx;
spin_lock_irq(>list_lock);
- block = list_first_entry_or_null(>outgoing, struct
- iio_dma_buffer_block, head);
- if (block != NULL) {
- list_del(>head);
+
+ idx = queue->fileio.next_dequeue;
+ block = queue->fileio.blocks[idx];
+
+ if (block->state == IIO_BLOCK_STATE_DONE) {
block->state = IIO_BLOCK_STATE_DEQUEUED;
+ idx = (idx + 1) % ARRAY_SIZE(queue->fileio.blocks);
+ queue->fileio.next_dequeue = idx;
+ } else {
+ block = NULL;
}
+
spin_unlock_irq(>list_lock);
return block;
@@ -539,6 +537,7 @@ size_t iio_dma_buffer_data_available(struct iio_buffer *buf)
struct iio_dma_buffer_queue *queue = iio_buffer_to_queue(buf);
struct iio_dma_buffer_block *block;
size_t data_available = 0;
+ unsigned int i;
/*
* For counting the available bytes we'll use the size of the block not
@@ -552,8 +551,15 @@ size_t iio_dma_buffer_data_available(struct iio_buffer
*buf)
data_available += queue->fileio.active_block->size;
