Re: [PATCH/RFT] fbdev driver for HP Visualize FX cards

[Sven Schnelle <svens@stackframe.org>]

Thomas Zimmermann <tzimmermann@suse.de> writes:

> Hi
>
> Am 01.11.21 um 09:54 schrieb Sven Schnelle:
>> Hi Thomas,
>> Thomas Zimmermann <tzimmermann@suse.de> writes:
>> Thanks, i wasn't aware as i normally don't do any graphics related
>> development. I take a look at dri and port the driver, which is
>> hopefully not too hard.
>
> Sounds good.
>
> The one big difference when converting is that DRM really wants
> drivers to support 32-bit XRGB colors. It's not a DRM limitation per
> se, but a requirement of today's userspace programs. AFAICS your fbdev
> driver uses a 256-color palette format. So the DRM driver would have
> to convert
> XRGB8888 to 8-bit RGB332 and install a corresponding palette. Don't
> worry, it's easy. Take a look at the cirrus driver for a simple DRM
> driver. [1]

I have converted the driver, but am using FORMAT_C8 because i haven't
figured out yet how to switch the card to XRGB8888. That's still on the
TODO list.

One question about hw blitting: with the old fbdev framework one could
replace the fb_imageblit function. For normal console text, this
function gets called with a monochrome bitmap, and an fg/bg color value.
This makes it easy to use HW accelerated blitting for text. In the
gpu/drm drivers i think i found only one driver (nouveau) doing this and
that was via the drm fbdev layer.

Is that still the way to go, or is there a better way to do HW accelerated
text blitting?

Thanks
Sven