linux-kernel - Re: [PATCH v12 1/3] drm: rockchip: Add basic drm driver

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Message-ID: <20141118142447.GC25711@phenom.ffwll.local>
Date:	Tue, 18 Nov 2014 15:24:47 +0100
From:	Daniel Vetter <daniel@...ll.ch>
To:	Boris Brezillon <boris.brezillon@...e-electrons.com>
Cc:	Daniel Vetter <daniel@...ll.ch>,
	Mark Yao <mark.yao@...k-chips.com>, heiko@...ech.de,
	David Airlie <airlied@...il.com>,
	Rob Clark <robdclark@...il.com>,
	Rob Herring <robh+dt@...nel.org>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	Randy Dunlap <rdunlap@...radead.org>,
	Grant Likely <grant.likely@...aro.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	John Stultz <john.stultz@...aro.org>,
	Rom Lemarchand <romlem@...gle.com>, devicetree@...r.kernel.org,
	linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
	dri-devel@...ts.freedesktop.org, linux-api@...r.kernel.org,
	linux-rockchip@...ts.infradead.org, dianders@...omium.org,
	marcheu@...omium.org, dbehr@...omium.org, olof@...om.net,
	djkurtz@...omium.org, cf@...k-chips.com, xxm@...k-chips.com,
	huangtao@...k-chips.com, kever.yang@...k-chips.com,
	yxj@...k-chips.com, xw@...k-chips.com
Subject: Re: [PATCH v12 1/3] drm: rockchip: Add basic drm driver

On Tue, Nov 18, 2014 at 02:21:30PM +0100, Boris Brezillon wrote:
> Hi Daniel,
> 
> On Tue, 18 Nov 2014 09:32:34 +0100
> Daniel Vetter <daniel@...ll.ch> wrote:
> 
> > On Tue, Nov 18, 2014 at 04:00:29PM +0800, Mark Yao wrote:
> > > From: Mark yao <mark.yao@...k-chips.com>
> > > 
> > > This patch adds the basic structure of a DRM Driver for Rockchip Socs.
> > > 
> > > Signed-off-by: Mark Yao <mark.yao@...k-chips.com>
> > > Signed-off-by: Daniel Kurtz <djkurtz@...omium.org>
> > > Acked-by: Daniel Vetter <daniel@...ll.ch>
> > > Reviewed-by: Rob Clark <robdclark@...il.com>
> > > ---
> > > Changes in v2:
> > > - use the component framework to defer main drm driver probe
> > >   until all VOP devices have been probed.
> > > - use dma-mapping API with ARM_DMA_USE_IOMMU, create dma mapping by
> > >   master device and each vop device can shared the drm dma mapping.
> > > - use drm_crtc_init_with_planes and drm_universal_plane_init.
> > > - remove unnecessary middle layers.
> > > - add cursor set, move funcs to rockchip drm crtc.
> > > - use vop reset at first init
> > > - reference framebuffer when used and unreference when swap out vop
> > > 
> > > Changes in v3:
> > > - change "crtc->fb" to "crtc->primary-fb"
> > > Adviced by Daniel Vetter
> > > - init cursor plane with universal api, remove unnecessary cursor set,move 
> > > 
> > > Changes in v4:
> > > Adviced by David Herrmann
> > > - remove drm_platform_*() usage, use register drm device directly.
> > 
> > Minor fixup for that part below.
> > 
> > [snip]
> > 
> > > +static int rockchip_drm_bind(struct device *dev)
> > > +{
> > > +	struct drm_device *drm;
> > > +	int ret;
> > > +
> > > +	drm = drm_dev_alloc(&rockchip_drm_driver, dev);
> > > +	if (!drm)
> > > +		return -ENOMEM;
> > > +
> > > +	ret = drm_dev_set_unique(drm, "%s", dev_name(dev));
> > > +	if (ret)
> > > +		goto err_free;
> > 
> > Please call rockchip_drm_load here directly and don't put it as the ->load
> > function into the driver vtable. The point of the alloc/register split is
> > that the driver can be completely set up _before_ we register anything.
> > But for backwards compat and historical reasons ->load is called somewhere
> > in the middle (so that you could access the minor nodes if needed, since
> > some drivers do that).
> 
> I tried to do the same in the atmel-hlcdc DRM driver, but I need the
> primary drm_minor to register the connectors (see this kernel
> backtrace [1]), which means I either initialize the connector in the
> wrong place (currently part of the drm load process), or I just can't
> call atmel_hlcdc_dc_load before registering the drm device...

Hm right, wonder who that works with rockchip tbh.

We did split up the drm_connector setup into _init and register, so if you
want to do this then you need to move the call to drm_connector_register
below the call to drm_dev_register.

We should probably have a drm_connectors_register_all helper which does
this for all connectors on the connector list. And also grabs the
appropriate lock.

I guess it's somewhat obvious that no one yet actually tried this ;-)
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch
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