nanogui: Thread: Shaky display

Hi Greg ..

There is a concern regarding microwindow for which we have already talked 
and now i have come up with more details so that we could find a solution 
to it. 

Let me explain you the problem in detail :-

1. It happens to be sometimes (1 in 20-30 times) that whenever i try to 
wtite a text to lcd display or fill a bar the text is written horizontaly 
about some percentage (say 50 %) and then again writes the same text the 
remaining percentage makeing the display as if one text is written twice 
half and half one over the other .

Similarly when we are dispalying the a horizontal bar the bar gers 
displayed two times one over the other horizontaly. 

Just to mention that this happens rarely and not always. 

Is there any thing we could see into the microwindow ???

Please do share your experience and knowledge regarding this concern .


 Thanks & Regards,
 Misbah
_____________________________________
  EmSyS Division,
  Larsen & Toubro Limited,
  KIADB indusrial area, Hebbal,Hootagalli.
  Mysore, 
  India 570018
  Phone: 08212405398  Extn: 5172
_____________________________________

This mail is classified as :
(  ) L&T EmSyS Proprietary 
(X) L&T EmSyS Confidential
(  ) L&T EmSyS Internal Use 
(  ) L&T EmSyS General Business



"Greg Haerr" ####@####.#### 
05/06/2008 08:51 PM
Please respond to
"Greg Haerr" ####@####.####


To
"Misbahullah Khan" ####@####.####
cc

Subject
Re: GrFillRect operation






You might discuss this on the list.  I would think this is very likely
a hardware issue.  Either writing to the display memory, or
something that the processor is doing may be causing this.
I am unaware of anything within microwindows that would cause this.
 
Does it only happen during text update, or the does display sometimes
just get shaky?
 
Regards,
 
Greg
----- Original Message ----- 
From: Misbahullah Khan 
To: Greg Haerr 
Sent: Tuesday, May 06, 2008 3:00 AM
Subject: Re: GrFillRect operation


Hi Greg ... 

Thanks for your reply . 

There is an issue i am facing with my project in which we have used 
microwindow for LCD GUI. The issue is this :- 

When we are displaying a string on LCD and sometimes highlighting the 
string it happens to be sometimes that the displayed string becomes shaky 
for a moment and then regains and becomes proper, it doesent hapens always 
and only sometimes. 

We need to know the probable cause of this problem and how to rectify it. 

Please do share your openion/experience in this regard 

Hoping for a reply soon 

 Thanks & Regards,
Misbah
_____________________________________
 EmSyS Division,
 Larsen & Toubro Limited,
 KIADB indusrial area, Hebbal,Hootagalli.
 Mysore, 
 India 570018
 Phone: 08212405398  Extn: 5172
_____________________________________

This mail is classified as :
(  ) L&T EmSyS Proprietary 
(X) L&T EmSyS Confidential
(  ) L&T EmSyS Internal Use 
(  ) L&T EmSyS General Business 


Greg Haerr ####@####.#### 
05/02/2008 07:11 PM 


To
Misbahullah Khan ####@####.#### 
cc

Subject
Re: GrFillRect operation








Look at the GrFillRect implementation in srvfunc.c to see the answer to 
your questions. You are looking at the client/server xfer code, below. 

Greg

Sent from my iPhone 

On Apr 29, 2008, at 4:27 AM, Misbahullah Khan <
####@####.#### wrote:


Hi Greg, 

void 
GrFillRect(GR_DRAW_ID id, GR_GC_ID gc, GR_COORD x, GR_COORD y, 
       GR_SIZE width, GR_SIZE height) 
{ 
       nxFillRectReq *req; 

       LOCK(&nxGlobalLock); 
       req = AllocReq(FillRect); 
       req->drawid = id; 
       req->gcid = gc; 
       req->x = x; 
       req->y = y; 
       req->width = width; 
       req->height = height; 
       UNLOCK(&nxGlobalLock); 
} 

I need to know the following implementation detail of GrFillRect() :- 

1. How and which driver is called by this Gr function? 
2. which low level driver / function is called accordingly ? 
3. which Global data/variable is updated by this (If any) ? 



Thanks & Regards,
Misbah
_____________________________________
EmSyS Division,
Larsen & Toubro Limited,
KIADB indusrial area, Hebbal,Hootagalli.
Mysore, 
India 570018
Phone: 08212405398  Extn: 5172
_____________________________________

This mail is classified as :
( ) L&T EmSyS Proprietary 
(X) L&T EmSyS Confidential
( ) L&T EmSyS Internal Use 
( ) L&T EmSyS General Business 

Hi Misbah, I can share my experience on this matter, too, as I had your 
same symptoms. Forgive me for top-posting.

My embedded system (arm-linux) includes a framebuffer driver which polls 
over /dev/fb0 a certain amount of times per second (about 30), so the 
time lag between a nano-x API call and the on-display effect is not a 
driver's fault. I noticed such time lag (some hundreds of second, 
partial refreshes, etc.) if the userspace process calls a nano-x API and 
goes immediately to sleep.  Otherwise, if the process, after the nano-x 
API call has to handle a message, a signal, a serial input, etc. the 
on-screen refresh is immediate and total. So I managed my process not to 
go to sleep immediately and the problem was solved.
By the way, I use statically linked nano-x lib, with 
LINK_APP_INTO_SERVER = Y into config file.

Hope this helps,

-- 
Carlo Zinato
Viscount International S.p.A.
R&D Labs, Ancona, Italy
Tel. & fax 0039 071 2905127/2905142
####@####.####

Misbahullah Khan ha scritto:
> Hi Greg ..
> 
> There is a concern regarding microwindow for which we have already talked 
> and now i have come up with more details so that we could find a solution 
> to it. 
> 
> Let me explain you the problem in detail :-
> 
> 1. It happens to be sometimes (1 in 20-30 times) that whenever i try to 
> wtite a text to lcd display or fill a bar the text is written horizontaly 
> about some percentage (say 50 %) and then again writes the same text the 
> remaining percentage makeing the display as if one text is written twice 
> half and half one over the other .
> 
> Similarly when we are dispalying the a horizontal bar the bar gers 
> displayed two times one over the other horizontaly. 
> 
> Just to mention that this happens rarely and not always. 
> 
> Is there any thing we could see into the microwindow ???
> 
> Please do share your experience and knowledge regarding this concern .
> 
> 
>  Thanks & Regards,
>  Misbah

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Carlo Zinato ha scritto:
> Hi Misbah, I can share my experience on this matter, too, as I had your 
> same symptoms. Forgive me for top-posting.

Obviously I meant HUNDREDTHS on seconds :)

-- 
Carlo Zinato
Viscount International S.p.A.
R&D Labs, Ancona, Italy
Tel. & fax 0039 071 2905127/2905142
####@####.####

No virus found in this outgoing message.
Checked by AVG. 
Version: 8.0.100 / Virus Database: 270.2.0/1493 - Release Date: 09/06/2008 17.25

Carlo Zinato ha scritto:
> Carlo Zinato ha scritto:
>> Hi Misbah, I can share my experience on this matter, too, as I had 
>> your same symptoms. Forgive me for top-posting.
> 
> Obviously I meant HUNDREDTHS on seconds :)

ARGH! need some caffeine...
I meant HUNDREDS OF MILLISECONDS!

-- 
Carlo Zinato
Viscount International S.p.A.
R&D Labs, Ancona, Italy
Tel. & fax 0039 071 2905127/2905142
####@####.####

No virus found in this outgoing message.
Checked by AVG. 
Version: 8.0.100 / Virus Database: 270.2.0/1493 - Release Date: 09/06/2008 17.25

: 1. It happens to be sometimes (1 in 20-30 times) that whenever i try to
: wtite a text to lcd display or fill a bar the text is written horizontaly
: about some percentage (say 50 %) and then again writes the same text the
: remaining percentage makeing the display as if one text is written twice
: half and half one over the other .
:
: Similarly when we are dispalying the a horizontal bar the bar gers
: displayed two times one over the other horizontaly.

I'm still confused as to whether you're describing a hardware
jitter or suggesting that perhaps the software is drawing
multiple times to appear "jittery."  I don't think there
are any known bugs regarding the latter.  I assume
you are running a straight framebuffer driver.  If not,
then there are additional drawing issues.

: Is there any thing we could see into the microwindow ???
:
: Please do share your experience and knowledge regarding this concern .

Carlo's response regarding the OS framebuffer driver sounds
like something that can definitely be related to visual strangeness.
Notice this also applies to a system where there isn't really
a memory-mapped framebuffer, but some other mechanism
for drawing.

Regards,

Greg 

This looks like an interlaced scan issue or something like that...
Could it be you need to draw the screen memory only during certain
times, e.g. when the screen is not physically refreshing?

Perhaps you need to wait for a vertical sync?

Regards,

Greg
  ----- Original Message ----- 
  From: Misbahullah Khan 
  To: Greg Haerr 
  Cc: ####@####.#### ; ####@####.#### ; Sanjeev GT 
  Sent: Wednesday, June 11, 2008 6:33 AM
  Subject: Re: [nanogui] Shaky display



  Hi Greg , 

  To give you a better idea of the exact display issue, i am enclosing the snapshot of the display. 

  >I assume
  >you are running a straight framebuffer driver.  If not,
  >then there are additional drawing issues.

  We have not enabled the framebuffer driver in the kernel.The screen driver in the 
  microwindow directly calls the lcd driver and also we are statically building the 
  nano-X lib. 

  As you have mentioned there could be some other drawing issue we would like to 
  know that. 




   Thanks & Regards,
  Misbah
  _____________________________________
   EmSyS Division,
   Larsen & Toubro Limited,
   KIADB indusrial area, Hebbal,Hootagalli.
   Mysore, 
   India 570018
   Phone: 08212405398  Extn: 5172
  _____________________________________

  This mail is classified as :
  (  ) L&T EmSyS Proprietary 
  (  ) L&T EmSyS Confidential
  (  ) L&T EmSyS Internal Use 
  (  ) L&T EmSyS General Business 


        "Greg Haerr" ####@####.#### 
        06/11/2008 05:03 AM Please respond to
              "Greg Haerr" ####@####.#### 


       To "Misbahullah Khan" ####@####.####  
              cc ####@####.####  
              Subject Re: [nanogui] Shaky display 

              

       



  : 1. It happens to be sometimes (1 in 20-30 times) that whenever i try to
  : wtite a text to lcd display or fill a bar the text is written horizontaly
  : about some percentage (say 50 %) and then again writes the same text the
  : remaining percentage makeing the display as if one text is written twice
  : half and half one over the other .
  :
  : Similarly when we are dispalying the a horizontal bar the bar gers
  : displayed two times one over the other horizontaly.

  I'm still confused as to whether you're describing a hardware
  jitter or suggesting that perhaps the software is drawing
  multiple times to appear "jittery."  I don't think there
  are any known bugs regarding the latter.  I assume
  you are running a straight framebuffer driver.  If not,
  then there are additional drawing issues.

  : Is there any thing we could see into the microwindow ???
  :
  : Please do share your experience and knowledge regarding this concern .

  Carlo's response regarding the OS framebuffer driver sounds
  like something that can definitely be related to visual strangeness.
  Notice this also applies to a system where there isn't really
  a memory-mapped framebuffer, but some other mechanism
  for drawing.

  Regards,

  Greg 


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  To unsubscribe, e-mail: ####@####.####
  For additional commands, e-mail: ####@####.####

Hi Greg ,

Even if i am accesseing the data RAM asynchronously there should not be 
any flickering at the display 
this is what the data sheet ( SPLC501C )says. Hence i assume that even i 
do access asynchronously 
the controller should refresh  and hence flickering should never happen.

>This looks like an interlaced scan issue or something like that...

>when the screen is not physically refreshing?

Screen should be refreshed by the controller always. when do you think 
that the 
screen should not be refreshing??

 Thanks & Regards,
 Misbah
_____________________________________
  EmSyS Division,
  Larsen & Toubro Limited,
  KIADB indusrial area, Hebbal,Hootagalli.
  Mysore, 
  India 570018
  Phone: 08212405398  Extn: 5172
_____________________________________

This mail is classified as :
(  ) L&T EmSyS Proprietary 
(  ) L&T EmSyS Confidential
(  ) L&T EmSyS Internal Use 
(  ) L&T EmSyS General Business



"Greg Haerr" ####@####.#### 
06/12/2008 09:17 PM
Please respond to
"Greg Haerr" ####@####.####


To
"Misbahullah Khan" ####@####.####
cc
####@####.#### ####@####.#### "Sanjeev GT" 
####@####.####
Subject
Re: [nanogui] Shaky display






This looks like an interlaced scan issue or something like that...
Could it be you need to draw the screen memory only during certain
times, e.g. when the screen is not physically refreshing?

Perhaps you need to wait for a vertical sync?

Regards,

Greg
  ----- Original Message ----- 
  From: Misbahullah Khan 
  To: Greg Haerr 
  Cc: ####@####.#### ; ####@####.#### ; Sanjeev GT 
  Sent: Wednesday, June 11, 2008 6:33 AM
  Subject: Re: [nanogui] Shaky display



  Hi Greg , 

  To give you a better idea of the exact display issue, i am enclosing the 
snapshot of the display. 

  >I assume
  >you are running a straight framebuffer driver.  If not,
  >then there are additional drawing issues.

  We have not enabled the framebuffer driver in the kernel.The screen 
driver in the 
  microwindow directly calls the lcd driver and also we are statically 
building the 
  nano-X lib. 

  As you have mentioned there could be some other drawing issue we would 
like to 
  know that. 




   Thanks & Regards,
  Misbah
  _____________________________________
   EmSyS Division,
   Larsen & Toubro Limited,
   KIADB indusrial area, Hebbal,Hootagalli.
   Mysore, 
   India 570018
   Phone: 08212405398  Extn: 5172
  _____________________________________

  This mail is classified as :
  (  ) L&T EmSyS Proprietary 
  (  ) L&T EmSyS Confidential
  (  ) L&T EmSyS Internal Use 
  (  ) L&T EmSyS General Business 


        "Greg Haerr" ####@####.#### 
        06/11/2008 05:03 AM Please respond to
              "Greg Haerr" ####@####.#### 


       To "Misbahullah Khan" ####@####.#### 
              cc ####@####.#### 
              Subject Re: [nanogui] Shaky display 

 

 



  : 1. It happens to be sometimes (1 in 20-30 times) that whenever i try 
to
  : wtite a text to lcd display or fill a bar the text is written 
horizontaly
  : about some percentage (say 50 %) and then again writes the same text 
the
  : remaining percentage makeing the display as if one text is written 
twice
  : half and half one over the other .
  :
  : Similarly when we are dispalying the a horizontal bar the bar gers
  : displayed two times one over the other horizontaly.

  I'm still confused as to whether you're describing a hardware
  jitter or suggesting that perhaps the software is drawing
  multiple times to appear "jittery."  I don't think there
  are any known bugs regarding the latter.  I assume
  you are running a straight framebuffer driver.  If not,
  then there are additional drawing issues.

  : Is there any thing we could see into the microwindow ???
  :
  : Please do share your experience and knowledge regarding this concern .

  Carlo's response regarding the OS framebuffer driver sounds
  like something that can definitely be related to visual strangeness.
  Notice this also applies to a system where there isn't really
  a memory-mapped framebuffer, but some other mechanism
  for drawing.

  Regards,

  Greg 


  ---------------------------------------------------------------------
  To unsubscribe, e-mail: ####@####.####
  For additional commands, e-mail: ####@####.####

Hi Greg ,

Even if i am accesseing the data RAM asynchronously there should not be 
any flickering at the display 
this is what the data sheet ( SPLC501C )says. Hence i assume that even i 
do access asynchronously 
the controller should refresh  and hence flickering should never happen at 
the display.

>This looks like an interlaced scan issue or something like that...

>when the screen is not physically refreshing?

Screen should be refreshed by the controller always. when do you think 
that the 
screen should not be refreshing??

Even if the data is written wrong due to inappropiate timing while 
writing, the screen should be refreshed at the next time and the user the 
should never see the data getting corrupted on the display. 

Could you please explain me how interlaced issue is related which you have 
mentioned earlier ????

 Thanks & Regards,
 Misbah
_____________________________________
  EmSyS Division,
  Larsen & Toubro Limited,
  KIADB indusrial area, Hebbal,Hootagalli.
  Mysore, 
  India 570018
  Phone: 08212405398  Extn: 5172
_____________________________________

This mail is classified as :
(  ) L&T EmSyS Proprietary 
(  ) L&T EmSyS Confidential
(  ) L&T EmSyS Internal Use 
(  ) L&T EmSyS General Business



"Greg Haerr" ####@####.#### 
06/12/2008 09:17 PM
Please respond to
"Greg Haerr" ####@####.####


To
"Misbahullah Khan" ####@####.####
cc
####@####.#### ####@####.#### "Sanjeev GT" 
####@####.####
Subject
Re: [nanogui] Shaky display






This looks like an interlaced scan issue or something like that...
Could it be you need to draw the screen memory only during certain
times, e.g. when the screen is not physically refreshing?

Perhaps you need to wait for a vertical sync?

Regards,

Greg
  ----- Original Message ----- 
  From: Misbahullah Khan 
  To: Greg Haerr 
  Cc: ####@####.#### ; ####@####.#### ; Sanjeev GT 
  Sent: Wednesday, June 11, 2008 6:33 AM
  Subject: Re: [nanogui] Shaky display



  Hi Greg , 

  To give you a better idea of the exact display issue, i am enclosing the 
snapshot of the display. 

  >I assume
  >you are running a straight framebuffer driver.  If not,
  >then there are additional drawing issues.

  We have not enabled the framebuffer driver in the kernel.The screen 
driver in the 
  microwindow directly calls the lcd driver and also we are statically 
building the 
  nano-X lib. 

  As you have mentioned there could be some other drawing issue we would 
like to 
  know that. 




   Thanks & Regards,
  Misbah
  _____________________________________
   EmSyS Division,
   Larsen & Toubro Limited,
   KIADB indusrial area, Hebbal,Hootagalli.
   Mysore, 
   India 570018
   Phone: 08212405398  Extn: 5172
  _____________________________________

  This mail is classified as :
  (  ) L&T EmSyS Proprietary 
  (  ) L&T EmSyS Confidential
  (  ) L&T EmSyS Internal Use 
  (  ) L&T EmSyS General Business 


        "Greg Haerr" ####@####.#### 
        06/11/2008 05:03 AM Please respond to
              "Greg Haerr" ####@####.#### 


       To "Misbahullah Khan" ####@####.#### 
              cc ####@####.#### 
              Subject Re: [nanogui] Shaky display 

 

 



  : 1. It happens to be sometimes (1 in 20-30 times) that whenever i try 
to
  : wtite a text to lcd display or fill a bar the text is written 
horizontaly
  : about some percentage (say 50 %) and then again writes the same text 
the
  : remaining percentage makeing the display as if one text is written 
twice
  : half and half one over the other .
  :
  : Similarly when we are dispalying the a horizontal bar the bar gers
  : displayed two times one over the other horizontaly.

  I'm still confused as to whether you're describing a hardware
  jitter or suggesting that perhaps the software is drawing
  multiple times to appear "jittery."  I don't think there
  are any known bugs regarding the latter.  I assume
  you are running a straight framebuffer driver.  If not,
  then there are additional drawing issues.

  : Is there any thing we could see into the microwindow ???
  :
  : Please do share your experience and knowledge regarding this concern .

  Carlo's response regarding the OS framebuffer driver sounds
  like something that can definitely be related to visual strangeness.
  Notice this also applies to a system where there isn't really
  a memory-mapped framebuffer, but some other mechanism
  for drawing.

  Regards,

  Greg 


  ---------------------------------------------------------------------
  To unsubscribe, e-mail: ####@####.####
  For additional commands, e-mail: ####@####.####

Greg Haerr ha scritto:
> 
> Carlo's response regarding the OS framebuffer driver sounds
> like something that can definitely be related to visual strangeness.
> Notice this also applies to a system where there isn't really
> a memory-mapped framebuffer, but some other mechanism
> for drawing.
> 
> Regards,
> 
> Greg 

Hi, Greg.
I digged a bit more on the problem of my framebuffer - lcd latency.
My embedded system has a framebuffer driver which reads /dev/fb0 and 
writes commands to the lcd controller either automatically (i.e. 
periodically) or on demand (via ioctl in user space). Writing directly 
to /dev/fb0 results into an immediate and total refresh of the lcd 
image, either with the driver working periodically and on demand.

I have several user space processes, and only one of them (let's call it 
process #1) is statically linked to and uses nano-x libs (with 
LINK_APP_INTO_SERVER = Y).

- 1st scenario: driver periodically reading /dev/fb0 and writing to the 
lcd controller, process #1 calls nano-x primitives to draw objects (e.g. 
via GrCopyArea) and goes to sleep, no other processes [R]un during and 
after process #1 is scheduled. The result is (often but not always) a 
partial lcd refresh followed by the refresh completion on the successive 
  periodic driver read/write.

- 2nd scenario: periodic driver r/w disabled, process #1 calls nano-x 
primitives, sends via ioctl to /dev/fb0 the refresh command and goes to 
sleep. No change results on the lcd. It's necessary to send another 
ioctl to see the total lcd refresh.

- 3rd scenario: periodic driver r/w disabled, process #1 calls nano-x 
primitives, calls sched_yield() to release cpu (but all other processes 
aren't waiting to be scheduled and continue to sleep), sends via ioctl 
to /dev/fb0 the refresh command and goes to sleep. No change results on 
the lcd. As above, it's necessary to send another ioctl to see the total 
lcd refresh.

- Last and resolving scenario: periodic driver r/w disabled, process #1 
calls nano-x primitives, sends a message to process #2 and calls 
sched_yield(), process #2 is scheduled, catches the message, does 
nothing more and goes to sleep, process #1 wakes up again immediately 
and sends via ioctl the refresh command and goes to sleep. The LCD 
refresh is always immediate and complete.

I didn't investigate into nano-x code deeply, but I suppose that the 
user space nano-x API calls are queued and not necessarily immediately 
executed if the scheduler doesn't deal with some kind of process 
rescheduling.

Best regards,

-- 
Carlo Zinato
Viscount International S.p.A.
R&D Labs, Ancona, Italy
Tel. & fax 0039 071 2905127/2905142
####@####.####

No virus found in this outgoing message.
Checked by AVG. 
Version: 8.0.100 / Virus Database: 270.4.1/1515 - Release Date: 23/06/2008 19.16