From: CK Hu <ck.hu@mediatek.com>
To: Daniel Vetter <daniel@ffwll.ch>
Cc: Frank Wunderlich <frank-w@public-files.de>,
David Airlie <airlied@linux.ie>,
Alexander Ryabchenko <d3adme4t@gmail.com>,
"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
dri-devel <dri-devel@lists.freedesktop.org>,
Matthias Brugger <matthias.bgg@gmail.com>,
"moderated list:ARM/Mediatek SoC support"
<linux-mediatek@lists.infradead.org>,
Philipp Zabel <p.zabel@pengutronix.de>,
Linux ARM <linux-arm-kernel@lists.infradead.org>
Subject: Re: Re: [PATCH] drm/mediatek: Add MTK Framebuffer-Device (mt7623)
Date: Fri, 11 Jan 2019 11:20:09 +0800 [thread overview]
Message-ID: <1547176809.12054.11.camel@mtksdaap41> (raw)
In-Reply-To: <20190110200225.GN21184@phenom.ffwll.local>
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?
Regards,
CK
next prev parent reply other threads:[~2019-01-11 3:20 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-02 8:49 [PATCH] drm/mediatek: Add MTK Framebuffer-Device (mt7623) Frank Wunderlich
2019-01-07 10:36 ` Daniel Vetter
2019-01-08 13:40 ` Daniel Vetter
2019-01-10 19:01 ` Aw: " Frank Wunderlich
2019-01-10 20:02 ` Daniel Vetter
2019-01-11 3:20 ` CK Hu [this message]
2019-01-11 9:20 ` Daniel Vetter
2019-01-11 9:49 ` CK Hu
2019-01-11 10:25 ` Daniel Vetter
2019-01-11 16:07 ` Noralf Trønnes
2019-01-14 2:02 ` CK Hu
2019-01-11 18:23 ` Aw: Re: " Frank Wunderlich
2019-01-11 1:31 ` Aw: " CK Hu
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