Re: [PATCH v6 1/3] drm/lsdc: add drm driver for loongson display controller

[Daniel Stone]

On Wed, 16 Feb 2022 at 14:13, Sui Jingfeng <15330273260@xxxxxx> wrote:
> On 2022/2/16 21:46, Daniel Stone wrote:
> > Other systems have this limitation, and Mesa's 'kmsro' concept makes
> > this work transparently, as long as your driver can export dmabufs
> > when running in 'VRAM' mode.
>
> When using vram helper based driver, the framebuffer  is locate at video
> ram. the backing memory fb is manage by TTM.
>
> while bo of etnaviv is locate at system ram. Currently i can't figure
> out how does the buffer going to be shared.

kmsro will allocate from the KMS device (usually using dumb buffers),
export that BO as a dmabuf, then import into etnaviv. etnaviv already
uses this for imx-drm.

Cheers,
Daniel