[PATCH RFC 6/8] drm: hisilicon: Add support for fbdev

[Xinliang Liu]

On 17 September 2015 at 19:52, Rob Clark <robdclark at gmail.com> wrote:

> On Wed, Sep 16, 2015 at 5:48 AM, Xinliang Liu <xinliang.liu at linaro.org>
> wrote:
> >
> >
> > On 16 September 2015 at 02:25, Rob Herring <robh at kernel.org> wrote:
> > Hi Rob, thanks a lot for reply:-)
> >
> >> On 09/15/2015 04:37 AM, Xinwei Kong wrote:
> >> > If you config DRM_HISI_FBDEV optional, this patch will only support
> >> > fbdev
> >> > mode while also supporting double buffer.
> >>
> >> This is a lot of duplicated code from CMA fbdev. Is double buffering the
> >> only reason why CMA fbdev can't be used or are there some other
> >> constraints?
> >
> > Yes, double buffering is the main reason we rewrite our own fbdev.
> > CMA fbdev only create one buffer. But we need at least  double buffer for
> > running Android with fbdev.
> >
> >> Double buffering in fbdev has always been a hack, so I'm
> >> guessing that is not a feature that should be added here.
> >>
> > If so, I think it is hard to be accepted for my cma fbdev patch to
> support
> > multi buffer.
> > This early week, I have sent a cma fbdev patch for supporting this. The
> > subject is
> > "[PATCH] drm/cma-helper: Add multi buffer support for cma fbdev".
> > We do have a strong will to support this feature. I described the reason
> in
> > the patch. Please take a look for me. Thank you very much.
>
> fwiw, drm_gralloc has support for kms.

We do have a plan to replace fbdev with kms. But it take time.


> Currently it is expected to be
> paired w/ a mesa gpu driver, which might not work for everyone, but I
> suppose the display part of it could be extracted out for a
> gralloc.kms.so for pure sw rendering.. that might be a better
> approach.
>

Yes, I also think kms should be handle in hwc rather than in gralloc.
IMO, gralloc should just handle dma buffer alloc and free.
We have a reference hwc implementation. which will handle kms inside it.
wiki:
https://wiki.linaro.org/BenjaminGaignard/HWComposer_DRM?highlight=%28hwcomposer%2
source code: git://git.linaro.org/people/benjamin.gaignard/hwcomposer.git

Cheers,
-Xinliang


> http://git.android-x86.org/?p=platform/hardware/drm_gralloc.git
>
> BR,
> -R
>
> > -Xinliang
> >
> >> Rob
> >>
> >> > Signed-off-by: Xinliang Liu <xinliang.liu at linaro.org>
> >> > Signed-off-by: Xinwei Kong <kong.kongxinwei at hisilicon.com>
> >> > Signed-off-by: Andy Green <andy.green at linaro.org>
> >> > Signed-off-by: Jiwen Qi <qijiwen at hisilicon.com>
> >> > Signed-off-by: Yu Gong <gongyu at hisilicon.com>
> >> > ---
> >> >  drivers/gpu/drm/hisilicon/Kconfig              |  13 +
> >> >  drivers/gpu/drm/hisilicon/Makefile             |   3 +-
> >> >  drivers/gpu/drm/hisilicon/hisi_drm_connector.c |   4 +
> >> >  drivers/gpu/drm/hisilicon/hisi_drm_drv.c       |   9 +
> >> >  drivers/gpu/drm/hisilicon/hisi_drm_dsi.c       |  15 +
> >> >  drivers/gpu/drm/hisilicon/hisi_drm_fb.h        |   5 +
> >> >  drivers/gpu/drm/hisilicon/hisi_drm_fbdev.c     | 395
> >> > +++++++++++++++++++++++++
> >> >  drivers/gpu/drm/hisilicon/hisi_drm_fbdev.h     |  24 ++
> >> >  8 files changed, 467 insertions(+), 1 deletion(-)
> >> >  create mode 100644 drivers/gpu/drm/hisilicon/hisi_drm_fbdev.c
> >> >  create mode 100644 drivers/gpu/drm/hisilicon/hisi_drm_fbdev.h
> >>
> >
> >
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> > http://lists.freedesktop.org/mailman/listinfo/dri-devel
> >
>
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