Re: [PATCH 3/3] [FBDEV]: Hardware State Notification

[Benjamin Herrenschmidt <benh@kernel.crashing.org>]

On Mon, 2004-06-21 at 17:39, Antonino A. Daplas wrote:
> Hi,
> 
> **This patch is more of an RFC.  BenH probably has similar code.
> 
> This patch adds a method (con_notify) that will notify console drivers of 
> impending console switches, passing them with the about-to-be-old (last)
> vc structure and about-to-be-new (wanted) vc structure.  The console 
> drivers can then elect to pass selected information to low-level drivers.
> 
> This is important to fbcon so it can detect a switch from a graphics console to a
> text console and vice versa. This will give underlying drivers a chance to update
> its hardware state. This is added via the  method fbcon_state_switch(). Fbcon
> will, however, do a set_par if the _state_switch method is not availabe and if
> switching from a KD_GRAPHICS console.
> 
> Also updated rivafb to take advantage of this method.  With this, switching
> to/from X with XFree86/Org nv driver works.  Usually it hangs without the
> option usefbdev, or gets a Sig11 if with option usefbdev.
> 
> (Unfortunately it doesn't work for nVidia's binary nvidia driver, switching to 
> the console is possible, switching back to X will hang the machine).

You don't need that. A method for that was _ALREADY_ added to the kernel,
it's based on the fact that the blank() callback is called on switches
between KD_TEXT and KD_GRAPHICS. After discussing the issue with Linus,
we decided to add a parameter to it indicating the nature of the
switch. You should be able to rely on that. Actually, if you look at
the code, I'm forcing a set_par in this case. If this doesn't work, then
I may have missed a code path, and that should be fixed but there is no
need at this point to change the infrastructure.

Ben.




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