Hi
Am 26.03.19 um 17:03 schrieb Adam Jackson:
> On Tue, 2019-03-26 at 10:17 +0100, Thomas Zimmermann wrote:
>
>> +static bool is_generic_driver(const struct fb_info *fb_info)
>> +{
>> + /* DRM porting note: We don't want to bind to vga16fb, vesafb, or any
>> + * other generic fbdev driver. Usually, these drivers have limited
>> + * capabilitis. We only continue if the fix structure indicates a
>> + * hardware-specific drivers . This test will also sort out drivers
>> + * registered via DRM's fbdev emulation. If you're porting an fbdev
>> + * driver to DRM, you can remove this test. The module's PCI device
>> + * ids will contain this information.
>> + */
>> + return !fb_info->fix.accel &&
>> + !!strcmp(fb_info->fix.id, "S3 Virge/DX");
>> +}
>
> This seems odd. s3fb sets fix.accel to NULL unconditionally AFAICT, not
> sure why you're testing for that explicitly.
If accel is 0, it might be a generic driver. Hence, fbdevdrm ignored
s3fb, so I added the exception.
> I do have a question though: why _not_ support generic fbdev drivers?
> If I had that, and the ability to disable creation of /dev/fb*, I could
> expose a consistent video device enumeration to userspace. As it stands
> I have no reasonable way of knowing which fbdev and drm devices are
> pointed at the same hardware. If there were only drm devices...
Ignoring generic drivers seemed like the safe bet for now. I found that
vga16fb, vesafb, etc bind to hardware and later get replaced by
HW-specific drivers; DRM drivers with FB emulation should not be handled
by fbdevdrm. So for now, fbdevdrm ignores all this.
This all comes from using the event-reporting mechanism to hook into the
fbdev module. Daniel suggested to copy over some of the fbdev drivers
for porting, which would solve the problem.
Best regards
Thomas
>
> - ajax
>
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Linux GmbH, Maxfeldstrasse 5, 90409 Nuernberg, Germany
GF: Felix Imendörffer, Mary Higgins, Sri Rasiah
HRB 21284 (AG Nürnberg)
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