From: Maxime Ripard <maxime.ripard@free-electrons.com>
To: Mike Turquette <mturquette@baylibre.com>,
Stephen Boyd <sboyd@codeaurora.org>,
David Airlie <airlied@linux.ie>,
Thierry Reding <thierry.reding@gmail.com>,
devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, linux-clk@vger.kernel.org,
dri-devel@lists.freedesktop.org, linux-sunxi@googlegroups.com,
Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
Chen-Yu Tsai <wens@csie.org>, Hans de Goede <hdegoede@redhat.com>,
Alexander Kaplan <alex@nextthing.co>,
Wynter Woods <wynter@nextthing.co>,
Boris Brezillon <boris.brezillon@free-electrons.com>,
Thomas Petazzoni <thomas.petazzoni@free-electrons.com>,
Rob Clark <robdclark@gmail.com>
Subject: Re: [PATCH 08/19] drm: Add Allwinner A10 Display Engine support
Date: Wed, 11 Nov 2015 14:14:12 -0800 [thread overview]
Message-ID: <20151111221412.GH6114@lukather> (raw)
In-Reply-To: <20151030144409.GZ16848@phenom.ffwll.local>
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Hi Daniel,
Thanks for your review!
On Fri, Oct 30, 2015 at 03:44:09PM +0100, Daniel Vetter wrote:
> > +static void sun4i_crtc_disable(struct drm_crtc *crtc)
> > +{
> > + struct sun4i_crtc *scrtc = drm_crtc_to_sun4i_crtc(crtc);
> > + struct sun4i_drv *drv = scrtc->drv;
> > +
> > + DRM_DEBUG_DRIVER("Disabling the CRTC\n");
> > +
> > + if (!scrtc->enabled)
> > + return;
>
> Please don't do this - the atomic state should always reflect the true hw
> state (fix that up with either hw state readout or reset in the ->reset
> callbacks), and the atomic helpers guarantee that they'll never call you
> when not needed. If you don't trust them do a WARN_ON at least, but no
> early silent returns.
>
> Personally I'd just rip it out, it's too much trouble. And for debugging
> the atomic helpers already trace it all (or at least should).
Ok. Is there a preferred way to do HW state readout, or should I just
add that to my probe?
> > +static int sun4i_drv_connector_plug_all(struct drm_device *drm)
>
> Laurent Pinchart has this as a rfc patch for drm core, please coordinate
> with him and rebase on top of his patches.
Ack, I will.
> > +static int sun4i_drv_enable_vblank(struct drm_device *drm, int pipe)
> > +{
> > + struct sun4i_drv *drv = drm->dev_private;
> > + struct sun4i_tcon *tcon = drv->tcon;
> > +
> > + DRM_DEBUG_DRIVER("Enabling VBLANK on pipe %d\n", pipe);
> > +
> > + sun4i_tcon_enable_vblank(tcon, true);
> > +
> > + return 0;
>
> atomic helpers rely on enable_vblank failing correctly when the pipe is
> off and vlbanks will never happen. You probably need a correct error code
> here that checks crtc->state->active (well not that directly but something
> derived from it, since the pointer chase would be racy).
Ok.
> I know it's a bit a mess since we don't have kms-native vblank driver
> hooks yet and really the drm core should get this right for you. It'll
> happen eventually, but drm_irq.c is a bit moldy ;-)
I can't really use drm_irq anyway, since we don't have a single
interrupt for the VBLANK, but two, that we have to use depending on
the output.
> > +static void sun4i_drv_disable_vblank(struct drm_device *drm, int pipe)
> > +{
> > + struct sun4i_drv *drv = drm->dev_private;
> > + struct sun4i_tcon *tcon = drv->tcon;
> > +
> > + DRM_DEBUG_DRIVER("Disabling VBLANK on pipe %d\n", pipe);
> > +
> > + sun4i_tcon_enable_vblank(tcon, false);
> > +}
> > +
> > +static int sun4i_drv_load(struct drm_device *drm, unsigned long flags)
>
> load/unload callbacks are depracated since fundamentally racy, and we
> can't fix that due to the pile of legacy dri1 drivers. Please use
> drm_dev_alloc/register/unregister/unref functions instead, with the
> load/unload code placed in between to avoid races with userspace seeing
> the device/driver (e.g. in sysfs) while it's in a partially defunct state.
>
> Relevant kerneldoc has the details, at least in linux-next.
Ok.
> > +static void sun4i_backend_layer_atomic_update(struct drm_plane *plane,
> > + struct drm_plane_state *old_state)
> > +{
> > + struct sun4i_layer *layer = plane_to_sun4i_layer(plane);
> > + struct sun4i_drv *drv = layer->drv;
> > + struct sun4i_backend *backend = drv->backend;
> > +
> > + sun4i_backend_update_layer_coord(backend, layer->id, plane);
> > + sun4i_backend_update_layer_formats(backend, layer->id, plane);
> > + sun4i_backend_update_layer_buffer(backend, layer->id, plane);
> > + sun4i_backend_layer_enable(backend, layer->id, true);
> > + sun4i_backend_commit(backend);
>
> Not idea how exactly your hw works, but the call to sun4i_backend_commit
> probably should be in the crtc->atomic_flush function, to make sure that
> plane updates across multiple planes are indeed atomic.
The hardware will not take the register writes into account until a
bit is set (in the _commit function), so I guess putting it in
atomic_flush makes sense.
Thanks!
Maxime
--
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
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next prev parent reply other threads:[~2015-11-11 22:14 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-30 14:20 [PATCH 00/19] drm: Add Allwinner A10 display engine support Maxime Ripard
2015-10-30 14:20 ` [PATCH 01/19] clk: sunxi: Add display clock Maxime Ripard
2015-10-30 21:29 ` Stephen Boyd
2015-11-06 23:39 ` Maxime Ripard
2015-11-12 20:31 ` Stephen Boyd
2015-11-19 15:42 ` Maxime Ripard
2015-10-31 10:28 ` Chen-Yu Tsai
2015-11-06 19:42 ` Maxime Ripard
2015-10-30 14:20 ` [PATCH 02/19] clk: sunxi: Add PLL3 clock Maxime Ripard
2015-10-30 21:32 ` Stephen Boyd
2015-10-30 14:20 ` [PATCH 03/19] clk: sunxi: Add TCON channel0 clock Maxime Ripard
2015-10-31 10:19 ` Chen-Yu Tsai
2015-11-06 22:11 ` Maxime Ripard
2015-10-30 14:20 ` [PATCH 04/19] clk: sunxi: Add TCON channel1 clock Maxime Ripard
2015-10-30 21:37 ` Stephen Boyd
2015-11-07 0:11 ` Maxime Ripard
2015-10-31 9:53 ` Chen-Yu Tsai
2015-11-07 0:01 ` Maxime Ripard
2015-11-09 3:36 ` Chen-Yu Tsai
2015-11-19 15:35 ` Maxime Ripard
2015-10-30 14:20 ` [PATCH 05/19] clk: sunxi: add DRAM gates Maxime Ripard
2015-11-09 4:18 ` Chen-Yu Tsai
2015-11-13 8:08 ` Chen-Yu Tsai
2015-11-19 15:43 ` Maxime Ripard
2015-10-30 14:20 ` [PATCH 06/19] clk: sunxi: Add Allwinner R8 AHB gates support Maxime Ripard
2015-10-30 16:01 ` Chen-Yu Tsai
2015-10-30 16:33 ` Hans de Goede
2015-10-30 14:20 ` [PATCH 07/19] drm/panel: simple: Add timings for the Olimex LCD-OLinuXino-4.3TS Maxime Ripard
2015-10-30 17:32 ` Thierry Reding
2015-11-07 0:44 ` Maxime Ripard
2015-10-30 14:20 ` [PATCH 08/19] drm: Add Allwinner A10 Display Engine support Maxime Ripard
2015-10-30 14:44 ` Daniel Vetter
2015-11-11 22:14 ` Maxime Ripard [this message]
2015-11-16 15:04 ` Daniel Vetter
2015-10-30 14:20 ` [PATCH 09/19] drm: sun4i: Add DT bindings documentation Maxime Ripard
2015-10-30 16:40 ` Rob Herring
2015-10-30 17:37 ` Thierry Reding
2015-11-01 14:28 ` Rob Herring
2015-11-06 22:32 ` Maxime Ripard
2015-10-30 14:20 ` [PATCH 10/19] drm: sun4i: Add RGB output Maxime Ripard
2015-10-30 14:20 ` [PATCH 11/19] drm: sun4i: Add composite output Maxime Ripard
2015-11-02 2:53 ` [linux-sunxi] " Jonathan Liu
2015-11-07 0:35 ` Maxime Ripard
2015-10-30 14:20 ` [PATCH 12/19] drm: sun4i: tv: Add PAL output standard Maxime Ripard
2015-10-30 14:20 ` [PATCH 13/19] drm: sun4i: tv: Add NTSC " Maxime Ripard
2015-10-30 14:21 ` [PATCH 14/19] ARM: sun5i: dt: Add pll3 and pll7 clocks Maxime Ripard
2015-11-09 4:24 ` Chen-Yu Tsai
2015-10-30 14:21 ` [PATCH 15/19] ARM: sun5i: dt: Add display and TCON clocks Maxime Ripard
2015-10-30 14:21 ` [PATCH 16/19] ARM: sun5i: dt: Add DRAM gates Maxime Ripard
2015-10-30 14:21 ` [PATCH 17/19] ARM: sun5i: dt: Add display blocks to the DTSI Maxime Ripard
2015-10-30 14:21 ` [PATCH 18/19] ARM: sun5i: r8: Add AHB gates " Maxime Ripard
2015-10-30 14:21 ` [PATCH 19/19] ARM: sun5i: chip: Enable the TV Encoder Maxime Ripard
2015-10-30 15:20 ` Chen-Yu Tsai
2015-11-06 19:37 ` Maxime Ripard
2015-10-30 14:52 ` [PATCH 00/19] drm: Add Allwinner A10 display engine support Daniel Vetter
2015-11-12 5:12 ` Maxime Ripard
2015-11-09 3:43 ` Chen-Yu Tsai
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