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>,
"Noralf Trønnes" <noralf@tronnes.org>,
"moderated list:ARM/Mediatek SoC support"
<linux-mediatek@lists.infradead.org>,
"Philipp Zabel" <p.zabel@pengutronix.de>,
"Matthias Brugger" <matthias.bgg@gmail.com>,
"Linux ARM" <linux-arm-kernel@lists.infradead.org>
Subject: Re: Re: [PATCH] drm/mediatek: Add MTK Framebuffer-Device (mt7623)
Date: Fri, 11 Jan 2019 17:49:15 +0800 [thread overview]
Message-ID: <1547200155.4209.4.camel@mtksdaap41> (raw)
In-Reply-To: <20190111092042.GP21184@phenom.ffwll.local>
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
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2019-01-11 9:49 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20190102084917.4049-1-frank-w@public-files.de>
2019-01-07 10:36 ` [PATCH] drm/mediatek: Add MTK Framebuffer-Device (mt7623) 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
2019-01-11 9:20 ` Daniel Vetter
2019-01-11 9:49 ` CK Hu [this message]
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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1547200155.4209.4.camel@mtksdaap41 \
--to=ck.hu@mediatek.com \
--cc=airlied@linux.ie \
--cc=d3adme4t@gmail.com \
--cc=daniel@ffwll.ch \
--cc=dri-devel@lists.freedesktop.org \
--cc=frank-w@public-files.de \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mediatek@lists.infradead.org \
--cc=matthias.bgg@gmail.com \
--cc=noralf@tronnes.org \
--cc=p.zabel@pengutronix.de \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).