Re: [PATCH v2 1/6] SoC Camera: add driver for OMAP1 camera interface
On Wed, 22 Sep 2010, Janusz Krzysztofik wrote:
Wednesday 22 September 2010 01:23:22 Guennadi Liakhovetski napisał(a):
On Sat, 11 Sep 2010, Janusz Krzysztofik wrote:
+
+ vb = buf-vb;
+ if (waitqueue_active(vb-done)) {
+ if (!pcdev-ready result != VIDEOBUF_ERROR)
+ /*
+ * No next buffer has been entered into the DMA
+ * programming register set on time, so best we can do
+ * is stopping the capture before last DMA block,
+ * whether our CONTIG mode whole buffer or its last
+ * sgbuf in SG mode, gets overwritten by next frame.
+ */
Hm, why do you think it's a good idea? This specific buffer completed
successfully, but you want to fail it just because the next buffer is
missing? Any specific reason for this?
Maybe my comment is not clear enough, but the below suspend_capture() doesn't
indicate any failure on a frame just captured. It only prevents the frame
from being overwritten by the already autoreinitialized DMA engine, pointing
back to the same buffer once again.
Besides, you seem to also be
considering the possibility of your -ready == NULL, but the queue
non-empty, in which case you just take the next buffer from the queue and
continue with it. Why error out in this case?
pcdev-ready == NULL means no buffer was available when it was time to put it
into the DMA programming register set.
But how? Buffers are added onto the list in omap1_videobuf_queue() under
spin_lock_irqsave(); and there you also check -ready and fill it in. In
your completion you set -ready = NULL, but then also call
prepare_next_vb() to get the next buffer from the list - if there are any,
so, how can it be NULL with a non-empty list?
As a result, a next DMA transfer has
just been autoreinitialized with the same buffer parameters as before. To
protect the buffer from being overwriten unintentionally, we have to stop the
DMA transfer as soon as possible, hopefully before the sensor starts sending
out next frame data.
If a new buffer has been queued meanwhile, best we can do is stopping
everything, programming the DMA with the new buffer, and setting up for a new
transfer hardware auto startup on nearest frame start, be it the next one if
we are lucky enough, or one after the next if we are too slow.
And even if also the queue
is empty - still not sure, why.
I hope the above explanation clarifies why.
I'll try to rework the above comment to be more clear, OK? Any hints?
linux-2.6.36-rc3.orig/include/media/omap1_camera.h2010-09-03
22:34:02.0 +0200 +++
linux-2.6.36-rc3/include/media/omap1_camera.h 2010-09-08
23:41:12.0 +0200 @@ -0,0 +1,35 @@
+/*
+ * Header for V4L2 SoC Camera driver for OMAP1 Camera Interface
+ *
+ * Copyright (C) 2010, Janusz Krzysztofik jkrzy...@tis.icnet.pl
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#ifndef __MEDIA_OMAP1_CAMERA_H_
+#define __MEDIA_OMAP1_CAMERA_H_
+
+#include linux/bitops.h
+
+#define OMAP1_CAMERA_IOSIZE 0x1c
+
+enum omap1_cam_vb_mode {
+ CONTIG = 0,
+ SG,
+};
See above - are these needed here?
+
+#define OMAP1_CAMERA_MIN_BUF_COUNT(x)((x) == CONTIG ? 3 : 2)
ditto
I moved them both over to the header file because I was using the
OMAP1_CAMERA_MIN_BUF_COUNT(CONTIG) macro once from the platform code in order
to calculate the buffer size when calling the then NAKed
dma_preallocate_coherent_memory(). Now I could put them back into the driver
code, but if we ever get back to the concept of preallocating a contignuos
piece of memory from the platform init code, we might need them back here, so
maybe I should rather keep them, only rename the two enum values using a
distinct name space. What do you think is better for now?
Yeah, up to you, I'd say, but if you decide to keep them in the header,
please, use a namespace.
I'm satisfied with your answers to the rest of my questions / comments:)
Thanks
Guennadi
---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer
http://www.open-technology.de/
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Re: [PATCH v2 1/6] SoC Camera: add driver for OMAP1 camera interface
Thursday 23 September 2010 15:33:54 Guennadi Liakhovetski napisał(a):
On Wed, 22 Sep 2010, Janusz Krzysztofik wrote:
Wednesday 22 September 2010 01:23:22 Guennadi Liakhovetski napisał(a):
On Sat, 11 Sep 2010, Janusz Krzysztofik wrote:
+
+ vb = buf-vb;
+ if (waitqueue_active(vb-done)) {
+ if (!pcdev-ready result != VIDEOBUF_ERROR)
+ /*
+* No next buffer has been entered into the DMA
+* programming register set on time, so best we
can do
+* is stopping the capture before last DMA
block,
+* whether our CONTIG mode whole buffer or its
last
+* sgbuf in SG mode, gets overwritten by next
frame.
+*/
Hm, why do you think it's a good idea? This specific buffer completed
successfully, but you want to fail it just because the next buffer is
missing? Any specific reason for this?
Maybe my comment is not clear enough, but the below suspend_capture()
doesn't indicate any failure on a frame just captured. It only prevents
the frame from being overwritten by the already autoreinitialized DMA
engine, pointing back to the same buffer once again.
Besides, you seem to also be
considering the possibility of your -ready == NULL, but the queue
non-empty, in which case you just take the next buffer from the queue
and continue with it. Why error out in this case?
pcdev-ready == NULL means no buffer was available when it was time to
put it into the DMA programming register set.
But how? Buffers are added onto the list in omap1_videobuf_queue() under
spin_lock_irqsave(); and there you also check -ready and fill it in.
Guennadi,
Yes, but only if pcdev-active is NULL, ie. both DMA and FIFO are idle, never
if active:
+ list_add_tail(vb-queue, pcdev-capture);
+ vb-state = VIDEOBUF_QUEUED;
+
+ if (pcdev-active)
+ return;
Since the transfer of the DMA programming register set content to the DMA
working register set is done automatically by the DMA hardware, this can
pretty well happen while I keep the lock here, so I can't be sure if it's not
too late for entering new data into the programming register set. Then, I
decided that this operation should be done only just after the DMA interrupt
occured, ie. the current DMA programming register set content has just been
used and can be overwriten.
I'll emphasize the above return; with a comment.
In
your completion you set -ready = NULL, but then also call
prepare_next_vb() to get the next buffer from the list - if there are any,
so, how can it be NULL with a non-empty list?
It happens after the above mentioned prepare_next_vb() gets nothing from an
empty queue, so nothing is entered into the DMA programming register set,
only the last, just activated, buffer is processed, then
omap1_videobuf_queue() puts a new buffer into the queue while the active
buffer is still filled in, and finally the DMA ISR is called on this last
active buffer completion.
I hope this helps.
As a result, a next DMA transfer has
just been autoreinitialized with the same buffer parameters as before. To
protect the buffer from being overwriten unintentionally, we have to stop
the DMA transfer as soon as possible, hopefully before the sensor starts
sending out next frame data.
If a new buffer has been queued meanwhile, best we can do is stopping
everything, programming the DMA with the new buffer, and setting up for a
new transfer hardware auto startup on nearest frame start, be it the next
one if we are lucky enough, or one after the next if we are too slow.
And even if also the queue
is empty - still not sure, why.
I hope the above explanation clarifies why.
I'll try to rework the above comment to be more clear, OK? Any hints?
linux-2.6.36-rc3.orig/include/media/omap1_camera.h 2010-09-03
22:34:02.0 +0200 +++
linux-2.6.36-rc3/include/media/omap1_camera.h 2010-09-08
23:41:12.0 +0200 @@ -0,0 +1,35 @@
+/*
+ * Header for V4L2 SoC Camera driver for OMAP1 Camera Interface
+ *
+ * Copyright (C) 2010, Janusz Krzysztofik jkrzy...@tis.icnet.pl
+ *
+ * This program is free software; you can redistribute it and/or
modify + * it under the terms of the GNU General Public License
version 2 as + * published by the Free Software Foundation.
+ */
+
+#ifndef __MEDIA_OMAP1_CAMERA_H_
+#define __MEDIA_OMAP1_CAMERA_H_
+
+#include linux/bitops.h
+
+#define OMAP1_CAMERA_IOSIZE0x1c
+
+enum omap1_cam_vb_mode {
+ CONTIG = 0,
+ SG,
+};
See above - are these needed here?
+
+#define OMAP1_CAMERA_MIN_BUF_COUNT(x) ((x) == CONTIG ? 3 : 2)
ditto
I moved them both over to the header file
Re: [PATCH v2 1/6] SoC Camera: add driver for OMAP1 camera interface
On Thu, 23 Sep 2010, Janusz Krzysztofik wrote:
Thursday 23 September 2010 15:33:54 Guennadi Liakhovetski napisał(a):
On Wed, 22 Sep 2010, Janusz Krzysztofik wrote:
Wednesday 22 September 2010 01:23:22 Guennadi Liakhovetski napisał(a):
On Sat, 11 Sep 2010, Janusz Krzysztofik wrote:
+
+ vb = buf-vb;
+ if (waitqueue_active(vb-done)) {
+ if (!pcdev-ready result != VIDEOBUF_ERROR)
+ /*
+ * No next buffer has been entered into the DMA
+ * programming register set on time, so best we
can do
+ * is stopping the capture before last DMA
block,
+ * whether our CONTIG mode whole buffer or its
last
+ * sgbuf in SG mode, gets overwritten by next
frame.
+ */
Hm, why do you think it's a good idea? This specific buffer completed
successfully, but you want to fail it just because the next buffer is
missing? Any specific reason for this?
Maybe my comment is not clear enough, but the below suspend_capture()
doesn't indicate any failure on a frame just captured. It only prevents
the frame from being overwritten by the already autoreinitialized DMA
engine, pointing back to the same buffer once again.
Besides, you seem to also be
considering the possibility of your -ready == NULL, but the queue
non-empty, in which case you just take the next buffer from the queue
and continue with it. Why error out in this case?
pcdev-ready == NULL means no buffer was available when it was time to
put it into the DMA programming register set.
But how? Buffers are added onto the list in omap1_videobuf_queue() under
spin_lock_irqsave(); and there you also check -ready and fill it in.
Guennadi,
Yes, but only if pcdev-active is NULL, ie. both DMA and FIFO are idle, never
if active:
+ list_add_tail(vb-queue, pcdev-capture);
+ vb-state = VIDEOBUF_QUEUED;
+
+ if (pcdev-active)
+ return;
Since the transfer of the DMA programming register set content to the DMA
working register set is done automatically by the DMA hardware, this can
pretty well happen while I keep the lock here, so I can't be sure if it's not
too late for entering new data into the programming register set. Then, I
decided that this operation should be done only just after the DMA interrupt
occured, ie. the current DMA programming register set content has just been
used and can be overwriten.
I'll emphasize the above return; with a comment.
Ok
In
your completion you set -ready = NULL, but then also call
prepare_next_vb() to get the next buffer from the list - if there are any,
so, how can it be NULL with a non-empty list?
It happens after the above mentioned prepare_next_vb() gets nothing from an
empty queue, so nothing is entered into the DMA programming register set,
only the last, just activated, buffer is processed, then
omap1_videobuf_queue() puts a new buffer into the queue while the active
buffer is still filled in, and finally the DMA ISR is called on this last
active buffer completion.
I hope this helps.
Let's assume it does:) You seem to really understand how this is working
and even be willing to document the driver, thus making it possibly the
best documented soc-camera related piece of software;)
Thanks
Guennadi
---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer
http://www.open-technology.de/
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Re: [PATCH v2 1/6] SoC Camera: add driver for OMAP1 camera interface
On Wed, 22 Sep 2010, hermann pitton wrote:
Am Mittwoch, den 22.09.2010, 01:23 +0200 schrieb Guennadi Liakhovetski:
On Sat, 11 Sep 2010, Janusz Krzysztofik wrote:
This is a V4L2 driver for TI OMAP1 SoC camera interface.
[snip]
+
+ } else {
+ dev_warn(dev, %s: unhandled camera interrupt, status ==
+ 0x%0x\n, __func__, it_status);
Please, don't split strings
sorry for any OT interference.
But, are there any new rules out?
Maybe I missed them.
Either way, the above was forced during the last three years.
Not at all ?
No. Splitting print strings has always been discouraged, because it makes
tracking back kernel logs difficult. The reason for this has been the 80
character line length limit, which has now been effectively lifted. I'm
sure you can find enough links on the internet for any of these topics.
Thanks
Guennadi
---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer
http://www.open-technology.de/
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Re: [PATCH v2 1/6] SoC Camera: add driver for OMAP1 camera interface
Wednesday 22 September 2010 01:23:22 Guennadi Liakhovetski napisał(a):
On Sat, 11 Sep 2010, Janusz Krzysztofik wrote:
This is a V4L2 driver for TI OMAP1 SoC camera interface.
Both videobuf-dma versions are supported, contig and sg, selectable with
a module option. The former uses less processing power, but often fails
to allocate contignuous buffer memory. The latter is free of this
problem, but generates tens of DMA interrupts per frame. If contig memory
allocation ever fails, the driver falls back to sg automatically on next
open, but still can be switched back to contig manually. Both paths work
stable for me, even under heavy load, on my OMAP1510 based Amstrad Delta
videophone, that is the oldest, least powerfull OMAP1 implementation.
The interface generally works in pass-through mode. Since input data byte
endianess can be swapped, it provides up to two v4l2 pixel formats per
each of several soc_mbus formats that have their swapped endian
counterparts.
Boards using this driver can provide it with the followning information:
- if and what freqency clock is expected by an on-board camera sensor,
- what is the maximum pixel clock that should be accepted from the
sensor, - what is the polarity of the sensor provided pixel clock,
- if the interface GPIO line is connected to a sensor reset/powerdown
input and what is the input polarity.
Created and tested against linux-2.6.36-rc3 on Amstrad Delta.
Signed-off-by: Janusz Krzysztofik jkrzy...@tis.icnet.pl
---
Friday 30 July 2010 13:07:42 Guennadi Liakhovetski wrote:
So, I think, a very welcome improvement to the driver would be a
cleaner separation between the two cases. Don't try that much to reuse
the code as much as possible. Would be much better to have clean
separation between the two implementations - whether dynamically
switchable at runtime or at config time - would be best to separate the
two
implementations to the point, where each of them becomes understandable
and maintainable.
Guennadi,
I've tried to rearrange them spearated, as you requested, but finally
decided to keep them together, as before, only better documented and
cleaned up as much as possible. I'm rather satisfied with the result, but
if you think it is still not enough understandable and maintainable, I'll
take one more iteration and split both paths.
Well, I think, I'll move a bit towards the if it breaks - someone gets to
fix it, or it gets dropped policy, i.e., I'll give you more freedom
(don't know what's wrong with me today;))
Hi Guennadi,
Thanks!
...
+#define DMA_FRAME_SHIFT(x) (x ? DMA_FRAME_SHIFT_SG : \
+ DMA_FRAME_SHIFT_CONTIG)
Don't you want to compare (x) against CONTIG and you want to put x in
parenthesis in the DMA_FRAME_SHIFT macro.
Sure.
Besides, CONTIG and SG are not
good enough names to be defined in a header under include/... Looks like
you don't need them at all in the header? You only use them in this file,
so, just move them inside.
Please see my very last comment below.
...
+static void videobuf_done(struct omap1_cam_dev *pcdev,
+ enum videobuf_state result)
+{
+ struct omap1_cam_buf *buf = pcdev-active;
+ struct videobuf_buffer *vb;
+ struct device *dev = pcdev-icd-dev.parent;
+
+ if (WARN_ON(!buf)) {
+ suspend_capture(pcdev);
+ disable_capture(pcdev);
+ return;
+ }
+
+ if (result == VIDEOBUF_ERROR)
+ suspend_capture(pcdev);
+
+ vb = buf-vb;
+ if (waitqueue_active(vb-done)) {
+ if (!pcdev-ready result != VIDEOBUF_ERROR)
+ /*
+* No next buffer has been entered into the DMA
+* programming register set on time, so best we can do
+* is stopping the capture before last DMA block,
+* whether our CONTIG mode whole buffer or its last
+* sgbuf in SG mode, gets overwritten by next frame.
+*/
Hm, why do you think it's a good idea? This specific buffer completed
successfully, but you want to fail it just because the next buffer is
missing? Any specific reason for this?
Maybe my comment is not clear enough, but the below suspend_capture() doesn't
indicate any failure on a frame just captured. It only prevents the frame
from being overwritten by the already autoreinitialized DMA engine, pointing
back to the same buffer once again.
Besides, you seem to also be
considering the possibility of your -ready == NULL, but the queue
non-empty, in which case you just take the next buffer from the queue and
continue with it. Why error out in this case?
pcdev-ready == NULL means no buffer was available when it was time to put it
into the DMA programming register set. As a result, a next DMA transfer has
just been autoreinitialized with the same
Re: [PATCH v2 1/6] SoC Camera: add driver for OMAP1 camera interface
Am Mittwoch, den 22.09.2010, 08:08 +0200 schrieb Guennadi Liakhovetski:
On Wed, 22 Sep 2010, hermann pitton wrote:
Am Mittwoch, den 22.09.2010, 01:23 +0200 schrieb Guennadi Liakhovetski:
On Sat, 11 Sep 2010, Janusz Krzysztofik wrote:
This is a V4L2 driver for TI OMAP1 SoC camera interface.
[snip]
+
+ } else {
+ dev_warn(dev, %s: unhandled camera interrupt, status
==
+ 0x%0x\n, __func__, it_status);
Please, don't split strings
sorry for any OT interference.
But, are there any new rules out?
Maybe I missed them.
Either way, the above was forced during the last three years.
Not at all ?
No. Splitting print strings has always been discouraged, because it makes
tracking back kernel logs difficult. The reason for this has been the 80
character line length limit, which has now been effectively lifted. I'm
sure you can find enough links on the internet for any of these topics.
Thanks
Guennadi
---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer
http://www.open-technology.de/
Guennadi,
thanks for the update!
If somebody ever would like to waste time on it, lots of patches and
whole drivers have been forced into this limitations for strings too.
In fact, fixing only a few lines, including the offset, you almost
always did hit it.
I'm pleased to hear now, that this problem never did exist ;))
Cheers,
Hermann
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Re: [PATCH v2 1/6] SoC Camera: add driver for OMAP1 camera interface
Hi,
Am Mittwoch, den 22.09.2010, 01:23 +0200 schrieb Guennadi Liakhovetski:
On Sat, 11 Sep 2010, Janusz Krzysztofik wrote:
This is a V4L2 driver for TI OMAP1 SoC camera interface.
[snip]
+
+ } else {
+ dev_warn(dev, %s: unhandled camera interrupt, status ==
+ 0x%0x\n, __func__, it_status);
Please, don't split strings
sorry for any OT interference.
But, are there any new rules out?
Maybe I missed them.
Either way, the above was forced during the last three years.
Not at all ?
Cheers,
Hermann
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