Re: [PATCH 0/6] drm/msm: fbdev: Use client buffers

Thomas Zimmermann
2026-04-23T08:04:58Z

Hi

Am 22.04.26 um 02:14 schrieb Dmitry Baryshkov:
> On Tue, Apr 21, 2026 at 07:08:31PM +0300, Dmitry Baryshkov wrote:
>> On Tue, Apr 21, 2026 at 02:51:13PM +0200, Thomas Zimmermann wrote:
>>> A client buffer holds the DRM framebuffer for an in-kernel DRM
>>> client. Until now, msm created an internal ad-hoc framebuffer for
>>> its fbdev emulation, while by-passing the regular interfaces used by
>>> user-space compositors.
>> I assume this was somewhat because we supported using the stolen memory
>> for FB. Support for it has been dropped when we moved to GPUVM.
>>
>> Rob, would it be possible to get it back at some point?
>>
>> Thomas, would the series prevent us from using the stolen memory for FB?
> And answering my question, no, we still can continue using stolen memory
> for the FB.

Indeed. The idea here is to keep the GEM buffer allocation as it is;
including stolen memory.   Once all driver's fbdev emulation uses the
client-buffer interfaces, we might be able to create the framebuffer in
the shared fbdev helpers.

As I mentioned in my reply to patch 4, the GEM buffer object is
something like fbdev framebuffer memory (i.e., video ram). In a later
change, we could allocate all of the stolen memory unconditionally.

Best regards
Thomas

>

--
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Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com
GF: Jochen Jaser, Andrew McDonald, Werner Knoblich, (HRB 36809, AG Nürnberg)