Re: Fb rotation 2.6.x

["Antonino A. Daplas" <adaplas@hotpop.com>]

On Tuesday 15 March 2005 16:58, Komal Shah wrote:
> Hi All,
>
> We have added the code for hardware rotation in the
> framebuffer driver for omap242x processor from TI
> [2.6.x kernel].
>
> It has been reported to work on 2.4.x.
>
> But when I had made it changed for 2.6.x follwoing
> behaviour is seen:
>
> 1. When I rotate the framebuffer ( Linux logo screen)
> by 180 degree then it shows only Linux logo image for
> a second only and then it disappears.
>
> 2. Whereas while doing in 90 degree rotation, it shows
> the black square of Linux logo size on the 270 degree
> rotation position.
>
> The reasons we found are as below:
>
> -----------------snip-----------------
> That is because in 2.4, the fb_display's var structure
> is updated by the driver - which we do consistently.
> In 2.6, on the other hand, the fb_info's var structure
> is
> updated by the driver, and all the fb_displays are
> updated by either fb_mem or fb_con - which I think is
> not done correctly. Also the set_par function is
> called so many times - I don't understand why.

Sometimes people use multiple fbdevs mapped to different consoles, so a
set_par() is called for each fb_info mapped for each console.

I guess I can add an "already_initialized" flag so fbcon doesn't do multiple
set_pars().

>
> What is happening is that, first, fb_info's var
> structure is updated, which rotates the display. But
> this var does not get passed to the current
> fb_display's var. Then when the fbcon_switch function
> is called, the current fb_display's var settings are
> affected - which 'unrotates' the display.

What fields do you use in var that is important for rotation? Is it
var->rotate? If that is the case, just add those fields in struct display in
fbcon.h, and update the functions display_to_var() and var_to_display() in
fbcon.c to also include the said fields.

Tony




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