Re: [PATCH v4] DRM: add drm gem CMA helper

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Lars,

On Wednesday 08 August 2012 18:25:30 Lars-Peter Clausen wrote:
> On 08/08/2012 04:44 PM, Laurent Pinchart wrote:
> > On Wednesday 27 June 2012 15:30:18 Sascha Hauer wrote:
> >> Many embedded drm devices do not have a IOMMU and no dedicated
> >> memory for graphics. These devices use CMA (Contiguous Memory
> >> Allocator) backed graphics memory. This patch provides helper
> >> functions to be able to share the code. The code technically does
> >> not depend on CMA as the backend allocator, the name has been chosen
> >> because cma makes for a nice, short but still descriptive function
> >> prefix.
> >> 
> >> Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
> >> ---
> >> 
> >> changes since v3:
> >> - *really* use DIV_ROUND_UP(args->width * args->bpp, 8) to calculate the
> >> pitch changes since v2:
> >> - make drm_gem_cma_create_with_handle static
> >> - use DIV_ROUND_UP(args->width * args->bpp, 8) to calculate the pitch
> >> - make drm_gem_cma_vm_ops const
> >> - add missing #include <linux/export.h>
> >> changes since v1:
> >> - map whole buffer at mmap time, not page by page at fault time
> >> - several cleanups as suggested by Lars-Peter Clausen and Laurent
> >> Pinchart
> >> 
> >>  drivers/gpu/drm/Kconfig              |    6 +
> >>  drivers/gpu/drm/Makefile             |    1 +
> >>  drivers/gpu/drm/drm_gem_cma_helper.c |  251
> >>  +++++++++++++++++++++++++++++++
> >>  include/drm/drm_gem_cma_helper.h     |   44 ++++++
> >>  4 files changed, 302 insertions(+)
> >>  create mode 100644 drivers/gpu/drm/drm_gem_cma_helper.c
> >>  create mode 100644 include/drm/drm_gem_cma_helper.h
> >> 
> >> diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
> >> index dc5df12..8f362ec 100644
> >> --- a/drivers/gpu/drm/Kconfig
> >> +++ b/drivers/gpu/drm/Kconfig
> >> @@ -53,6 +53,12 @@ config DRM_TTM
> >> 
> >>  	  GPU memory types. Will be enabled automatically if a device driver
> >>  	  uses it.
> >> 
> >> +config DRM_GEM_CMA_HELPER
> >> +	tristate
> >> +	depends on DRM
> >> +	help
> >> +	  Choose this if you need the GEM CMA helper functions
> >> +
> >> 
> >>  config DRM_TDFX
> >>  
> >>  	tristate "3dfx Banshee/Voodoo3+"
> >>  	depends on DRM && PCI
> >> 
> >> diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile
> >> index 0487ff6..8759cda 100644
> >> --- a/drivers/gpu/drm/Makefile
> >> +++ b/drivers/gpu/drm/Makefile
> >> @@ -15,6 +15,7 @@ drm-y       :=	drm_auth.o drm_buffer.o drm_bufs.o
> >> drm_cache.o \ drm_trace_points.o drm_global.o drm_prime.o
> >> 
> >>  drm-$(CONFIG_COMPAT) += drm_ioc32.o
> >> 
> >> +drm-$(CONFIG_DRM_GEM_CMA_HELPER) += drm_gem_cma_helper.o
> > 
> > This results in a built failure for me with
> > 
> > CONFIG_DRM=y
> > CONFIG_DRM_KMS_HELPER=m
> > # CONFIG_DRM_LOAD_EDID_FIRMWARE is not set
> > CONFIG_DRM_GEM_CMA_HELPER=m
> > CONFIG_DRM_KMS_CMA_HELPER=m
> > 
> > drm_gem_cma_helper.o isn't compiled at all. Can you reproduce the problem
> > ?
> 
> The Kconfig entry needs to be bool instead of tristate.

That's my preferred solution as well. I'll modify the patch in my tree, unless 
Sascha wants to submit a v5.

-- 
Regards,

Laurent Pinchart