Re: [U-Boot] Add video support for mx51evk

2010-11-02 Thread Wolfgang Denk
Dear Stefano Babic,

In message 4ccfb244.2000...@denx.de you wrote:

 Consider this, I do not think the actual computation in lcd_setmem() is
 correct. We need to compute the maximum amount of memory to be reserved
 to the framebuffer, not the value requested by the current display
 interface. We could add a CONFIG_SYS_VIDEO_SIZE that contains the
 maximum amount of memory needed, because the value is strictly
 board-dependent, and change lcd_setmem to use it. Anatolij, what do you
 think about this ?

Why cannot you determine the exact amount needed at runtime?

Best regards,

Wolfgang Denk

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Re: [U-Boot] Add video support for mx51evk

2010-11-02 Thread Stefano Babic
On 11/02/2010 09:35 AM, Wolfgang Denk wrote:
 Dear Stefano Babic,
 
 In message 4ccfb244.2000...@denx.de you wrote:

 Consider this, I do not think the actual computation in lcd_setmem() is
 correct. We need to compute the maximum amount of memory to be reserved
 to the framebuffer, not the value requested by the current display
 interface. We could add a CONFIG_SYS_VIDEO_SIZE that contains the
 maximum amount of memory needed, because the value is strictly
 board-dependent, and change lcd_setmem to use it. Anatolij, what do you
 think about this ?
 
 Why cannot you determine the exact amount needed at runtime?

Agree, we can do it, and it is better - I do not think we need really to
change dinamically (I mean, in the same u-boot session) the LCD
connected to the framebuffer, reason that requires to reserve the
maximum amount of memory.

We could introduce a weak function, that a board maintainer can decide
to implement or not. This maintains the compatibility with the most
drivers where vpanel is static initialized.

Stefano

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Re: [U-Boot] Add video support for mx51evk

2010-11-02 Thread Anatolij Gustschin
Hi,

On Tue, 02 Nov 2010 07:40:04 +0100
Stefano Babic sba...@denx.de wrote:
...
  There is also a second issue where I would like to know your thoughts. Very
  early on system initialization, when LCD is enabled, there is a call to
  lcd_setmem from board.c. By that time, the video variables,
  panel_info, are
  not set yet. Thus U-Boot doesn't reserve the appropriate amount of
  memory for
  the display. I was going to set panel_info variable on mx51evk.c, but
  I would like to know how you solved it for vision2 first. 
 
 Thanks for pointing out, I have already seen the point, but at the end I
 forget to fix it ;-). Probably because there is no side-effects on this
 board, but this does not mean that the issue should not fixed for
 vision2, too.
 
 The problem arises from the fact that the setup of the display
 parameters was static and everything was solved at compile time. With
 the framebuffer for the MX51, I needed the possibility to change
 dinamically the parameters, because the board can have different LCD
 displays.
 
 Consider this, I do not think the actual computation in lcd_setmem() is
 correct. We need to compute the maximum amount of memory to be reserved
 to the framebuffer, not the value requested by the current display
 interface. We could add a CONFIG_SYS_VIDEO_SIZE that contains the
 maximum amount of memory needed, because the value is strictly
 board-dependent, and change lcd_setmem to use it. Anatolij, what do you
 think about this ?

We should reserve the amount of memory we actually need for the
used display configuration, I think. Reserving the maximum amount
would be needed if we have to support switching the display
resolution at runtime, but I don't think that this is needed in
your case. Therefore I prefer the solution that reserves the
actually needed amount of memory.

Best regards,
Anatolij
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Re: [U-Boot] Add video support for mx51evk

2010-11-02 Thread Wolfgang Denk
Dear Stefano Babic,

In message 4ccfd2fb.6060...@denx.de you wrote:

  Why cannot you determine the exact amount needed at runtime?
 
 Agree, we can do it, and it is better - I do not think we need really to
 change dinamically (I mean, in the same u-boot session) the LCD
 connected to the framebuffer, reason that requires to reserve the
 maximum amount of memory.

Right. If we keep in mind the possibility to share the frame buffer
with Linux (to allow for a flicker-free display of a splash screen
loaded very early in U-Boot) we should stick with the memory map we
have: pRAM on top, frame buffer below, U-Boot code below, etc.  That
means that size changes for the frame buffer (like for pRAM) take only
effect after a reset.

 We could introduce a weak function, that a board maintainer can decide
 to implement or not. This maintains the compatibility with the most
 drivers where vpanel is static initialized.

In which way is this board dependent?

Best regards,

Wolfgang Denk

-- 
DENX Software Engineering GmbH, MD: Wolfgang Denk  Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: w...@denx.de
Philosophy:  A route of many roads leading from nowhere to nothing.
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Re: [U-Boot] Add video support for mx51evk

2010-11-02 Thread Stefano Babic
On 11/02/2010 10:42 AM, Wolfgang Denk wrote:
 Dear Stefano Babic,
 

Hi Wolfgang,

 We could introduce a weak function, that a board maintainer can decide
 to implement or not. This maintains the compatibility with the most
 drivers where vpanel is static initialized.
 
 In which way is this board dependent?

Because each board uses a different LCD with a different resolution, and
this requires a different amount of memory. This is not different as we
see in Linux, because the framebuffer properties are set in the board
file before to be passed to the framebuffer driver.

Best regards,
Stefano

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Re: [U-Boot] Add video support for mx51evk

2010-11-02 Thread Wolfgang Denk
Dear Stefano Babic,

In message 4ccfdeba.2070...@denx.de you wrote:

  We could introduce a weak function, that a board maintainer can decide
  to implement or not. This maintains the compatibility with the most
  drivers where vpanel is static initialized.
  
  In which way is this board dependent?
 
 Because each board uses a different LCD with a different resolution, and
 this requires a different amount of memory. This is not different as we
 see in Linux, because the framebuffer properties are set in the board
 file before to be passed to the framebuffer driver.

Well, if _that_ was what we are using, the memory requirements were
fixed, and we could use compile-time constants.

But what you discussed before was the option to _switch_ resolutions,
so there has to be a way to select the cosen resolution (in an
environment variable?), and then this setting is used for the memory
calculations.

And then the calculation depends only on the current setting - which
is _not_ board dependent.

Boards would start with a (board dependent) default setting, though.

Best regards,

Wolfgang Denk

-- 
DENX Software Engineering GmbH, MD: Wolfgang Denk  Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: w...@denx.de
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Re: [U-Boot] Add video support for mx51evk

2010-11-02 Thread Stefano Babic
On 11/02/2010 02:34 PM, Wolfgang Denk wrote:

 Because each board uses a different LCD with a different resolution, and
 this requires a different amount of memory. This is not different as we
 see in Linux, because the framebuffer properties are set in the board
 file before to be passed to the framebuffer driver.
 
 Well, if _that_ was what we are using, the memory requirements were
 fixed, and we could use compile-time constants.

I was not complete: a single board can be connected to several LCDs, of
course not at the same type. The decision which LCD must be used should
be taken baing on an environment variable.

 
 But what you discussed before was the option to _switch_ resolutions,
 so there has to be a way to select the cosen resolution (in an
 environment variable?),

Yes, this is what I meant

 and then this setting is used for the memory
 calculations.

Correct.

 
 And then the calculation depends only on the current setting - which
 is _not_ board dependent.

Yes, calculation is not board dependent and must remain in lcd_setmem().
What I meant as board dependent is really the LCD settings, in terms
of display resolution and bits x pixel. The proposed wek function can
set the panel_info structure, that lcd_setmem() uses for computation.

 
 Boards would start with a (board dependent) default setting, though.

Yes. What we need is a way to get the board default setting to allow
lcd_setmem() to compute the required memory.

Best regards,
Stefano Babic

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Re: [U-Boot] Add video support for mx51evk

2010-11-02 Thread Wolfgang Denk
Dear Stefano Babic,

In message 4cd035f7.9070...@denx.de you wrote:
 
  And then the calculation depends only on the current setting - which
  is _not_ board dependent.
 
 Yes, calculation is not board dependent and must remain in lcd_setmem().
 What I meant as board dependent is really the LCD settings, in terms
 of display resolution and bits x pixel. The proposed wek function can
 set the panel_info structure, that lcd_setmem() uses for computation.

Why do we need a board dependent function for that? We can adjust the
setings by storing their value in an environment variable, say some-
thing like 800x600...@60hz or copying what Linux does with the video-
mode= boot argument (we already have drivers/video/videomodes.c).
That should be precise enough, and is completely bosrd-independent.


  Boards would start with a (board dependent) default setting, though.
 
 Yes. What we need is a way to get the board default setting to allow
 lcd_setmem() to compute the required memory.

Let's re-use existing interfaces (especially if we then can pass the
very same variable as boot argument to Linux).

Best regards,

Wolfgang Denk

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HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: w...@denx.de
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Re: [U-Boot] Add video support for mx51evk

2010-11-02 Thread Renato Frias
Hello Stefano Babic,

On Tue, Nov 2, 2010 at 4:40 AM, Stefano Babic sba...@denx.de wrote:

 However, it is really better to make the modification for the vision2
 inside the same patchset. This guarantees that both boards work when
 your patches go to mainline.

Ok! Should I send the patch for vision2, also?

 Thanks for pointing out, I have already seen the point, but at the end I
 forget to fix it ;-). Probably because there is no side-effects on this
 board, but this does not mean that the issue should not fixed for
 vision2, too.

This issue affects the video mx51evk, at least for the patch I sent.
If I don't edit lcd.c the board resets when writing to the
framebuffer, upon boot.

Best Regards,
Renato
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