Hi, Daniel: On Fri, 2019-01-11 at 10:20 +0100, Daniel Vetter wrote: > On Fri, Jan 11, 2019 at 11:20:09AM +0800, CK Hu wrote: > > Hi, Daniel: > > > > On Thu, 2019-01-10 at 21:02 +0100, Daniel Vetter wrote: > > > On Thu, Jan 10, 2019 at 08:01:37PM +0100, Frank Wunderlich wrote: > > > > Hi Daniel, > > > > > > > > > > Would be good to use the new generic fbdev emulation code here, for even > > > > > > less code. Or at least know why this isn't possible to use for mtk (and > > > > > > maybe address that in the core code). Hand-rolling fbdev code shouldn't be > > > > > > needed anymore. > > > > > > > > > > Back on the mailing list, no private replies please: > > > > > > > > i don't wanted to spam all people with dumb questions ;) > > > > > > There's no dumb questions, only insufficient documentation :-) > > > > > > > > For examples please grep for drm_fbdev_generic_setup(). There's also a > > > > > still in-flight series from Gerd Hoffmann to convert over bochs. That, > > > > > plus all the kerneldoc linked from there should get you started. > > > > > -Daniel > > > > > > > > this is one of google best founds if i search for drm_fbdev_generic_setup: > > > > > > > > https://lkml.org/lkml/2018/12/19/305 > > > > > > > > not very helpful... > > > > > > > > so i tried kernel-doc > > > > > > > > https://www.kernel.org/doc/html/latest/gpu/drm-kms-helpers.html?highlight=drm_fbdev_generic_setup#c.drm_fbdev_generic_setup > > > > > > > > which is nice function-reference but i've found no generic workflow > > > > > > > > as the posted driver is "only" a driver ported from kernel 4.4 by Alexander, i don't know if this new framework can be used and which parts need to be changed. I only try to bring his code Mainline.... > > > > Maybe CK Hu can help here because driver is originally from him and he knows internals. Or maybe you can help here? > > > > > > > > i personally make my first steps as spare-time kernel-developer :) > > > > > > There's a ton of in-kernel users of that function already, I meant you can > > > use those to serve as examples ... If those + the kerneldoc aren't > > > good enough, then we need to improve them. > > > -Daniel > > > > I've tried with drm_fbdev_generic_setup() and it works fine with simple > > modification. The patch is > > > > --- a/drivers/gpu/drm/mediatek/mtk_drm_drv.c > > +++ b/drivers/gpu/drm/mediatek/mtk_drm_drv.c > > @@ -16,6 +16,7 @@ > > #include <drm/drm_atomic.h> > > #include <drm/drm_atomic_helper.h> > > #include <drm/drm_crtc_helper.h> > > +#include <drm/drm_fb_helper.h> > > #include <drm/drm_gem.h> > > #include <drm/drm_gem_cma_helper.h> > > #include <drm/drm_of.h> > > @@ -379,6 +380,7 @@ static void mtk_drm_kms_deinit(struct drm_device > > *drm) > > .gem_prime_get_sg_table = mtk_gem_prime_get_sg_table, > > .gem_prime_import_sg_table = mtk_gem_prime_import_sg_table, > > .gem_prime_mmap = mtk_drm_gem_mmap_buf, > > + .gem_prime_vmap = mtk_drm_gem_prime_vmap, > > .ioctls = mtk_ioctls, > > .num_ioctls = ARRAY_SIZE(mtk_ioctls), > > .fops = &mtk_drm_fops, > > @@ -416,6 +418,8 @@ static int mtk_drm_bind(struct device *dev) > > if (ret < 0) > > goto err_deinit; > > > > + drm_fbdev_generic_setup(drm, 32); > > + > > return 0; > > > > > > But I implement .gem_prime_vmap with a workaround, > > > > > > --- a/drivers/gpu/drm/mediatek/mtk_drm_gem.c > > +++ b/drivers/gpu/drm/mediatek/mtk_drm_gem.c > > @@ -280,3 +280,8 @@ int mtk_gem_create_ioctl(struct drm_device *dev, > > void *data, > > mtk_drm_gem_free_object(&mtk_gem->base); > > return ret; > > } > > + > > +void *mtk_drm_gem_prime_vmap(struct drm_gem_object *obj) > > +{ > > + return (void *)1; > > +} > > > > Current drm_fb_helper depends on drm_client to create fbdev. When > > drm_client create drm_client_buffer, it need to vmap to get kernel > > vaddr. But I think for fbdev, the vaddr is useless. Do you agree that I > > temporarily implement .gem_prime_vmap in such way? > > The vmap is used by fbcon, without that fbdev won't really work I think. > So I'm rather confused on what you tested ... > > Adding Noralf, he's the expert here. > -Daniel I test with fb_test [1], it is a user space program just open /dev/fb0 and mmap it to user space. I does not turn on fbcon so everything looks well. If support fbcon is essential, I would implement vmap correctly. If it's not essential, I think I could return 0 when CONFIG_FRAMBUFFER_CONSOLE is defined. Regards, CK [1] https://android.googlesource.com/platform/system/extras/+/master/tests/framebuffer/fb_test.c _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
