Re: [PATCH v3 3/7] drm/vc4: Add KMS support for Raspberry Pi.

From: Stefan Wahren
Date: Sun Oct 11 2015 - 10:02:19 EST

Hi Eric,

Am 09.10.2015 um 23:27 schrieb Eric Anholt:
This is enough for fbcon and bringing up X using
xf86-video-modesetting. It doesn't support the 3D accelerator or
power management yet.

Signed-off-by: Eric Anholt <eric@xxxxxxxxxx>
Acked-by: Daniel Vetter <daniel.vetter@xxxxxxxx>
---

v2: Drop FB_HELPER select thanks to Archit's patches. Do manual init
ordering instead of using the .load hook. Structure registration
more like tegra's, but still using the typical "component" code.
Drop no-op hooks for atomic_begin and mode_fixup() now that
they're optional. Drop sentinel in Makefile. Fix minor style
nits I noticed on another reread.

v3: Use the new bcm2835 clk driver to manage pixel/HSM clocks instead
of having a fixed video mode. Use exynos-style component driver
matching instead of devicetree nodes to list the component driver
instances. Rename compatibility strings to say bcm2835, and
distinguish pv0/1/2. Clean up some h/vsync code, and add in
interlaced mode setup. Fix up probe/bind error paths. Use
bitops.h macros for vc4_regs.h

drivers/gpu/drm/Kconfig | 2 +
drivers/gpu/drm/Makefile | 1 +
drivers/gpu/drm/vc4/Kconfig | 13 +
drivers/gpu/drm/vc4/Makefile | 17 +
drivers/gpu/drm/vc4/vc4_bo.c | 52 +++
drivers/gpu/drm/vc4/vc4_crtc.c | 675 ++++++++++++++++++++++++++++++++++++++
drivers/gpu/drm/vc4/vc4_debugfs.c | 39 +++
drivers/gpu/drm/vc4/vc4_drv.c | 284 ++++++++++++++++
drivers/gpu/drm/vc4/vc4_drv.h | 115 +++++++
drivers/gpu/drm/vc4/vc4_hdmi.c | 588 +++++++++++++++++++++++++++++++++
drivers/gpu/drm/vc4/vc4_hvs.c | 163 +++++++++
drivers/gpu/drm/vc4/vc4_kms.c | 54 +++
drivers/gpu/drm/vc4/vc4_plane.c | 320 ++++++++++++++++++
drivers/gpu/drm/vc4/vc4_regs.h | 570 ++++++++++++++++++++++++++++++++
14 files changed, 2893 insertions(+)
create mode 100644 drivers/gpu/drm/vc4/Kconfig
create mode 100644 drivers/gpu/drm/vc4/Makefile
create mode 100644 drivers/gpu/drm/vc4/vc4_bo.c
create mode 100644 drivers/gpu/drm/vc4/vc4_crtc.c
create mode 100644 drivers/gpu/drm/vc4/vc4_debugfs.c
create mode 100644 drivers/gpu/drm/vc4/vc4_drv.c
create mode 100644 drivers/gpu/drm/vc4/vc4_drv.h
create mode 100644 drivers/gpu/drm/vc4/vc4_hdmi.c
create mode 100644 drivers/gpu/drm/vc4/vc4_hvs.c
create mode 100644 drivers/gpu/drm/vc4/vc4_kms.c
create mode 100644 drivers/gpu/drm/vc4/vc4_plane.c
create mode 100644 drivers/gpu/drm/vc4/vc4_regs.h

diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
index 1a0a8df..c4bf9a1 100644
--- a/drivers/gpu/drm/Kconfig
+++ b/drivers/gpu/drm/Kconfig
@@ -264,3 +264,5 @@ source "drivers/gpu/drm/sti/Kconfig"
source "drivers/gpu/drm/amd/amdkfd/Kconfig"

source "drivers/gpu/drm/imx/Kconfig"
+
+source "drivers/gpu/drm/vc4/Kconfig"
diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile
index 45e7719..0edc9e2 100644
--- a/drivers/gpu/drm/Makefile
+++ b/drivers/gpu/drm/Makefile
@@ -42,6 +42,7 @@ obj-$(CONFIG_DRM_MGA) += mga/
obj-$(CONFIG_DRM_I810) += i810/
obj-$(CONFIG_DRM_I915) += i915/
obj-$(CONFIG_DRM_MGAG200) += mgag200/
+obj-$(CONFIG_DRM_VC4) += vc4/
obj-$(CONFIG_DRM_CIRRUS_QEMU) += cirrus/
obj-$(CONFIG_DRM_SIS) += sis/
obj-$(CONFIG_DRM_SAVAGE)+= savage/
diff --git a/drivers/gpu/drm/vc4/Kconfig b/drivers/gpu/drm/vc4/Kconfig
new file mode 100644
index 0000000..e810ef7
--- /dev/null
+++ b/drivers/gpu/drm/vc4/Kconfig
@@ -0,0 +1,13 @@
+config DRM_VC4
+ tristate "Broadcom VC4 Graphics"
+ depends on ARCH_BCM2835

depends on (ARCH_BCM2835 || COMPILE_TEST) ?

+ depends on DRM
+ select DRM_KMS_HELPER
+ select DRM_KMS_CMA_HELPER
+ help
+ Choose this option if you have a system that has a Broadcom
+ VC4 GPU, such as the Raspberry Pi or other BCM2708/BCM2835.
+
+ This driver requires that "avoid_warnings=2" be present in
+ the config.txt for the firmware, to keep it from smashing
+ our display setup.
+ [...]
+static void vc4_crtc_disable(struct drm_crtc *crtc)
+{
+ struct drm_device *dev = crtc->dev;
+ struct vc4_dev *vc4 = to_vc4_dev(dev);
+ struct vc4_crtc *vc4_crtc = to_vc4_crtc(crtc);
+ u32 chan = vc4_crtc->channel;
+
+ require_hvs_enabled(dev);
+
+ CRTC_WRITE(PV_V_CONTROL,
+ CRTC_READ(PV_V_CONTROL) & ~PV_VCONTROL_VIDEN);
+ while (CRTC_READ(PV_V_CONTROL) & PV_VCONTROL_VIDEN)
+ cpu_relax();
+
+ /* Without a wait here, we end up with a black screen. */
+ msleep(30);

This looks a little bit strange. First we do a busy loop without any timeout and then a fixed msleep without reason for the exact duration.

Sorry for the possibly dumb questions:

Is it safe to read PV_V_CONTROL exactly after writing to them? No sleeping required?

How did you come to the 30 milli seconds?

+ [...]
diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
new file mode 100644
index 0000000..ae37fec
--- /dev/null
+++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
@@ -0,0 +1,588 @@
+/*
+ * Copyright (C) 2015 Broadcom
+ * Copyright (c) 2014 The Linux Foundation. All rights reserved.
+ * Copyright (C) 2013 Red Hat
+ * Author: Rob Clark <robdclark@xxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/**
+ * DOC: VC4 Falcon HDMI module
+ *
+ * The HDMI core has a state machine and a PHY. Most of the unit
+ * operates off of the HSM clock from CPRMAN. It also internally uses
+ * the PLLH_PIX clock for the PHY.
+ */
+
+#include "drm_atomic_helper.h"
+#include "drm_crtc_helper.h"
+#include "drm_edid.h"
+#include "linux/clk.h"
+#include "linux/component.h"

#include "linux/i2c.h" ?

+#include "linux/of_gpio.h"
+#include "linux/of_platform.h"
+#include "vc4_drv.h"
+#include "vc4_regs.h"
+
+/* General HDMI hardware state. */
+struct vc4_hdmi {
+ struct platform_device *pdev;
+
+ struct drm_encoder *encoder;
+ struct drm_connector *connector;
+
+ struct i2c_adapter *ddc;
+ void __iomem *hdmicore_regs;
+ void __iomem *hd_regs;
+ int hpd_gpio;
+
+ struct clk *pixel_clock;
+ struct clk *hsm_clock;
+};
+

Best regards
Stefan

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