[PATCH 17/17] drm/cirrus: Use VGA macro constants to unblank

[Thomas Zimmermann]

Hi

Am 16.02.23 um 13:52 schrieb Ville Syrjälä:
> On Thu, Feb 16, 2023 at 01:03:02PM +0100, Thomas Zimmermann wrote:
>> Hi,
>>
>> thanks for taking a look at the patches.
>>
>> Am 16.02.23 um 12:33 schrieb Gerd Hoffmann:
>>> On Wed, Feb 15, 2023 at 05:15:17PM +0100, Thomas Zimmermann wrote:
>>>> Set the VGA bit for unblanking with macro constants instead of magic
>>>> values. No functional changes.
>>>
>>> blank/unblank should work simliar to bochs (see commit 250e743915d4),
>>> that is maybe a nice thing to add of you modernize the driver anyway.
>> Yeah, it's the VGA PAS field. [1] But is it really called blanking? PAS
>> controls palette access, but blanking is sounds more like DPMS.
> 
> Why aren't people just using the normal way of flipping the
> screen off bit in sequencer register 01?

Setting the SD bit in SR01 isn't a bad idea. We can do this as part of 
enabling/disabling the plane.

But for PAS, we don't have a choice. It's one of the bazillion obscure 
VGA settings and (according to a comment in the source code) we need to 
update it for compatibility.

Best regards
Thomas

> 
> 
>>
>> The PAS setting is actually part of the primary plane, so it's current
>> location in the CRTC code is misleading. I didn't want to change the
>> driver logic too much, but I guess I'll fix that in the next iteration.
>>
>> Best regards
>> Thomas
>>
>> [1]
>> https://web.stanford.edu/class/cs140/projects/pintos/specs/freevga/vga/attrreg.htm#3C0
>>
>>>
>>> take care,
>>>     Gerd
>>>
>>
>> -- 
>> Thomas Zimmermann
>> Graphics Driver Developer
>> SUSE Software Solutions Germany GmbH
>> Maxfeldstr. 5, 90409 Nürnberg, Germany
>> (HRB 36809, AG Nürnberg)
>> Geschäftsführer: Ivo Totev
> 
> 
> 
> 

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Ivo Totev
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