On 17 September 2015 at 19:52, Rob Clark robdclark@gmail.com wrote:
On Wed, Sep 16, 2015 at 5:48 AM, Xinliang Liu xinliang.liu@linaro.org wrote:
On 16 September 2015 at 02:25, Rob Herring robh@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=%28hwcompo... 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@linaro.org Signed-off-by: Xinwei Kong kong.kongxinwei@hisilicon.com Signed-off-by: Andy Green andy.green@linaro.org Signed-off-by: Jiwen Qi qijiwen@hisilicon.com Signed-off-by: Yu Gong gongyu@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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