Hi Daniel, On Thu, Feb 09, 2017 at 06:04:38PM +0100, Daniel Vetter wrote: > On Thu, Feb 02, 2017 at 11:31:56AM +0100, Maxime Ripard wrote: > > From: Xinliang Liu <xinliang.liu@xxxxxxxxxx> > > > > This patch add a config to support to create multi buffer for cma fbdev. > > Such as double buffer and triple buffer. > > > > Cma fbdev is convient to add a legency fbdev. And still many Android > > devices use fbdev now and at least double buffer is needed for these > > Android devices, so that a buffer flip can be operated. It will need > > some time for Android device vendors to abondon legency fbdev. So multi > > buffer for fbdev is needed. > > > > Signed-off-by: Xinliang Liu <xinliang.liu@xxxxxxxxxx> > > [s.christ@xxxxxxxxx: Picking patch from > > https://lkml.org/lkml/2015/9/14/188] > > Signed-off-by: Stefan Christ <s.christ@xxxxxxxxx> > > Signed-off-by: Maxime Ripard <maxime.ripard@xxxxxxxxxxxxxxxxxx> > > --- > > drivers/gpu/drm/Kconfig | 8 ++++++++ > > drivers/gpu/drm/drm_fb_cma_helper.c | 8 +++++++- > > 2 files changed, 15 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig > > index ebfe8404c25f..2ca9bb26a4e4 100644 > > --- a/drivers/gpu/drm/Kconfig > > +++ b/drivers/gpu/drm/Kconfig > > @@ -121,6 +121,14 @@ config DRM_KMS_CMA_HELPER > > help > > Choose this if you need the KMS CMA helper functions > > > > +config DRM_CMA_FBDEV_BUFFER_NUM > > + int "Cma Fbdev Buffer Number" > > + depends on DRM_KMS_CMA_HELPER > > + default 1 > > + help > > + Defines the buffer number of cma fbdev. Default is one buffer. > > + For double buffer please set to 2 and 3 for triple buffer. > > + > > source "drivers/gpu/drm/i2c/Kconfig" > > > > source "drivers/gpu/drm/arm/Kconfig" > > diff --git a/drivers/gpu/drm/drm_fb_cma_helper.c b/drivers/gpu/drm/drm_fb_cma_helper.c > > index 81b3558302b5..e3f8b9e720a0 100644 > > --- a/drivers/gpu/drm/drm_fb_cma_helper.c > > +++ b/drivers/gpu/drm/drm_fb_cma_helper.c > > @@ -411,6 +411,12 @@ static void drm_fbdev_cma_defio_fini(struct fb_info *fbi) > > kfree(fbi->fbops); > > } > > > > +static int fbdev_num_buffers = CONFIG_DRM_CMA_FBDEV_BUFFER_NUM; > > +module_param(fbdev_num_buffers, int, 0444); > > +MODULE_PARM_DESC(fbdev_num_buffers, > > + "Number of frame buffers to allocate [default=" > > + __MODULE_STRING(CONFIG_DRM_CMA_FBDEV_BUFFER_NUM) "]"); > > Pure bikshed: Should this be an overallocation %? 200 for > double-buffering, 100 as the default? I'm not against it, but would it make sense to allocate something like 120% of a buffer? > Slightly less bikesheddy: Can't we do this in the core helpers somehow? I guess that would move it to drm_fb_helper_single_fb_probe then? It makes sense. > I'd be nice if this is not cma specific. If it's not possible, I'd at > least move the symbol to drm_fb_helper.c, and add some kernel-doc around > it. That allows any other non-cma driver to at least implement support for > this. That also has the benefit of featuring it more prominently, in our > docs. I'll move it and add the kerneldoc. Thanks! Maxime -- Maxime Ripard, Free Electrons Embedded Linux and Kernel engineering http://free-electrons.com
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