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Date: Thu, 3 Feb 2022 09:53:35 +0100
From: Krzysztof Kozlowski <krzk@...nel.org>
To: Sui Jingfeng <15330273260@....cn>
Cc: Dan Carpenter <dan.carpenter@...cle.com>,
Lucas Stach <l.stach@...gutronix.de>,
Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
Maxime Ripard <mripard@...nel.org>,
Roland Scheidegger <sroland@...are.com>,
Zack Rusin <zackr@...are.com>,
Christian Gmeiner <christian.gmeiner@...il.com>,
David Airlie <airlied@...ux.ie>,
Daniel Vetter <daniel@...ll.ch>,
Rob Herring <robh+dt@...nel.org>,
Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
Andrey Zhizhikin <andrey.zhizhikin@...ca-geosystems.com>,
Sam Ravnborg <sam@...nborg.org>,
suijingfeng <suijingfeng@...ngson.cn>,
linux-mips@...r.kernel.org,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
dri-devel@...ts.freedesktop.org,
Randy Dunlap <rdunlap@...radead.org>
Subject: Re: [PATCH v6 1/3] drm/lsdc: add drm driver for loongson display controller
On Thu, 3 Feb 2022 at 09:26, Sui Jingfeng <15330273260@....cn> wrote:
>
> From: suijingfeng <suijingfeng@...ngson.cn>
>
> There is a display controller in loongson's LS2K1000 SoC and LS7A1000
> bridge, and the DC in those chip is a PCI device. This patch provide
> a minimal support for this display controller which is mainly for
> graphic environment bring up.
>
> This display controller has two display pipes but with only one hardware
> cursor. Each way has a DVO output interface and the CRTC is able to scanout
> from 1920x1080 resolution at 60Hz. The maxmium resolution is 2048x2048@...z.
>
> LS2K1000 is a SoC, only system memory is available. Therefore scanout from
> system memory is the only choice. We prefer the CMA helper base solution
> because the gc1000 gpu can use etnaviv driver, in this case etnaviv and
> lsdc could made a compatible pair. Even through it is possible to use VRAM
> helper base solution on ls2k1000 by carving out part of system memory as
> VRAM.
>
> For LS7A1000, there are 4 gpios whos control register is located at the dc
> register space which is not the geneal purpose GPIO. The 4 gpios can emulate
> two way i2c. One for DVO0, another for DVO1. This is the reason the why we
> are not using the drm bridge framework.
>
> LS2K1000 and LS2K0500 SoC don't have such hardware, they use general purpose
> GPIO emulated i2c or hardware i2c adapter from other module to serve this
> purpose. Drm bridge and drm panel is suitable for those SoC, we have already
> implement it on our own downstream kernel. But due to the upstream kernel
> don't have gpio, pwm and i2c driver support for LS2K1000. We just can not
> upstream our support for the drm bridge subsystem.
>
> The DC in LS7A1000 can scanout from both the system memory and the dedicate
> VRAM attached to the ddr3 memory controller. Sadly, only scanout from the
> VRAM is proved to be a reliable solution for massive product. Scanout from
> the system memory suffer from some hardware deficiency which cause the
> screen flickering under RAM pressure. This is the reason why we integrate
> two distict helpers into one piece of device driver. But CMA base helper is
> still usable on ls7a1000 for normal usage, expecially on ls7a1000+ bridge
> chip. We have also implemented demage update on top of CMA helper which
> copy the demaged shadow framebuffer region from system RAM to the real
> framebuffer in VRAM manually. Using "lsdc.dirty_update=1" in the commmand
> line will enable this driver mode.
>
> LS7A1000 have a 32x32 harware cursor, we just let the two CRTC share it
> simply with the help of universe plane. LS7A2000 have two 64x64 harware
> cursor. Surport for LS7A2000 is on the way.
>
> In short, we have built-in gpio emulated i2c support, we also have hardware
> cursor support. The kind of tiny drivers in drm/tiny is not suitable for us,
> we are not "tiny".
>
> +------+ HyperTransport 3.0
> | DDR4 | |
> +------+ | +------------------------------------+
> || MC0 | | LS7A1000 +------------|
> +----------+ | | | DDR3 | +------+
> | LS3A4000 |<--------->| +--------+ +-------+ | memory |<->| VRAM |
> | CPU |<--------->| | GC1000 | | LSDC | | controller | +------+
> +----------+ | +--------+ +-+---+-+ +------------|
> || MC1 +---------------|---|----------------+
> +------+ | |
> | DDR4 | +-------+ DVO0 | | DVO1 +------+
> +------+ VGA <--|ADV7125|<---------+ +------->|TFP410|--> DVI/HDMI
> +-------+ +------+
>
> The above picture give a simple usage of LS7A1000, note that the encoder
> is not necessary adv7125 or tfp410, it is a choice of the downstream board
> manufacturer. Other candicate encoder can be ch7034b, sil9022 and ite66121
> etc. Therefore, we need device tree to provide board specific information.
> Besides, the dc in both ls2k1000 and ls7k1000 have the vendor:device id of
> 0x0014:0x7a06, the reverison id is also same. We can't tell it apart simply
> (this is the firmware engineer's mistake). But firmware already flushed to
> the board and borad already sold out, we choose to resolve those issues by
> introduing device tree with board specific device support.
>
> For lsdc, there is only a 1:1 mapping of encoders and connectors.
>
> +-------------------+ _________
> | | | |
> | CRTC0 --> DVO0 ---------> Encoder0 --> Connector0 ---> | Monitor |
> | | ^ ^ |_________|
> | | | |
> | <----- i2c0 ----------------+
> | LSDC IP CORE |
> | <----- i2c1 ----------------+
> | | | | _________
> | | | | | |
> | CRTC1 --> DVO1 ---------> Encoder1 --> Connector1 ---> | Panel |
> | | |_________|
> +-------------------+
>
> Below is a brief introduction of loongson's CPU, bridge chip and SoC.
> LS2K1000 is a double core 1.0Ghz mips64r2 compatible SoC[1]. LS7A1000 is
> a bridge chip made by Loongson corporation which act as north and/or south
> bridge of loongson's desktop and server level processor. It is equivalent
> to AMD RS780E+SB710 or something like that. More details can be read from
> its user manual[2].
>
> This bridge chip is typically use with LS3A3000, LS3A4000 and LS3A5000 cpu.
> LS3A3000 is 4 core 1.45gHz mips64r2 compatible cpu.
> LS3A4000 is 4 core 1.8gHz mips64r5 compatible cpu.
> LS3A5000 is 4 core 2.5gHz loongarch cpu[3].
>
> Nearly all mordern loongson CPU's cache coherency is maintained by hardware,
> except for early version of ls2k1000. So we using cached coherent memory by
> default, not writecombine.
>
> v2: fixup warnings reported by kernel test robot
>
> v3: fix more grammar mistakes in Kconfig reported by Randy Dunlap and give
> more details about lsdc.
>
> v4:
> 1) Add dts required and explain why device tree is required.
> 2) Give more description about lsdc and vram helper base driver.
> 3) Fix warnings reported by kernel test robot.
> 4) Introduce stride_alignment member into struct lsdc_chip_desc, the
> stride alignment is 256 bytes for ls7a1000, ls2k1000 and ls2k0500 SoC.
> But ls7a2000 improve it to 32 bytes, We are prepare for extend the
> support for the on coming device.
>
> v5:
> 1) using writel and readl replace writeq and readq, to fix kernel test
> robot report build error on other archtecture
> 2) set default fb format to XRGB8888 at crtc reset time.
> 3) fix typos.
>
> v6:
> 1) Explain why we are not switch to drm dridge subsystem on ls2k1000.
> 2) Explain why tiny drm driver is not suitable for us.
> 3) Give a short description of the trival dirty uppdate implement based
> on CMA helper.
> 4) code clean up
>
> [1] https://wiki.debian.org/InstallingDebianOn/Lemote/Loongson2K1000
> [2] https://loongson.github.io/LoongArch-Documentation/Loongson-7A1000-usermanual-EN.html
> [3] https://loongson.github.io/LoongArch-Documentation/Loongson-3A5000-usermanual-EN.html
>
> Reported-by: Randy Dunlap <rdunlap@...radead.org>
> Reported-by: kernel test robot
> Signed-off-by: suijingfeng <suijingfeng@...ngson.cn>
> Signed-off-by: Sui Jingfeng <15330273260@....cn>
> ---
> drivers/gpu/drm/Kconfig | 2 +
> drivers/gpu/drm/Makefile | 1 +
> drivers/gpu/drm/lsdc/Kconfig | 38 ++
> drivers/gpu/drm/lsdc/Makefile | 15 +
> drivers/gpu/drm/lsdc/lsdc_connector.c | 443 ++++++++++++++
> drivers/gpu/drm/lsdc/lsdc_connector.h | 60 ++
> drivers/gpu/drm/lsdc/lsdc_crtc.c | 440 ++++++++++++++
> drivers/gpu/drm/lsdc/lsdc_drv.c | 846 ++++++++++++++++++++++++++
> drivers/gpu/drm/lsdc/lsdc_drv.h | 216 +++++++
> drivers/gpu/drm/lsdc/lsdc_encoder.c | 79 +++
> drivers/gpu/drm/lsdc/lsdc_i2c.c | 220 +++++++
> drivers/gpu/drm/lsdc/lsdc_i2c.h | 61 ++
> drivers/gpu/drm/lsdc/lsdc_irq.c | 77 +++
> drivers/gpu/drm/lsdc/lsdc_irq.h | 37 ++
> drivers/gpu/drm/lsdc/lsdc_plane.c | 681 +++++++++++++++++++++
> drivers/gpu/drm/lsdc/lsdc_pll.c | 657 ++++++++++++++++++++
> drivers/gpu/drm/lsdc/lsdc_pll.h | 109 ++++
> drivers/gpu/drm/lsdc/lsdc_regs.h | 246 ++++++++
> 18 files changed, 4228 insertions(+)
> create mode 100644 drivers/gpu/drm/lsdc/Kconfig
> create mode 100644 drivers/gpu/drm/lsdc/Makefile
> create mode 100644 drivers/gpu/drm/lsdc/lsdc_connector.c
> create mode 100644 drivers/gpu/drm/lsdc/lsdc_connector.h
> create mode 100644 drivers/gpu/drm/lsdc/lsdc_crtc.c
> create mode 100644 drivers/gpu/drm/lsdc/lsdc_drv.c
> create mode 100644 drivers/gpu/drm/lsdc/lsdc_drv.h
> create mode 100644 drivers/gpu/drm/lsdc/lsdc_encoder.c
> create mode 100644 drivers/gpu/drm/lsdc/lsdc_i2c.c
> create mode 100644 drivers/gpu/drm/lsdc/lsdc_i2c.h
> create mode 100644 drivers/gpu/drm/lsdc/lsdc_irq.c
> create mode 100644 drivers/gpu/drm/lsdc/lsdc_irq.h
> create mode 100644 drivers/gpu/drm/lsdc/lsdc_plane.c
> create mode 100644 drivers/gpu/drm/lsdc/lsdc_pll.c
> create mode 100644 drivers/gpu/drm/lsdc/lsdc_pll.h
> create mode 100644 drivers/gpu/drm/lsdc/lsdc_regs.h
>
> diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
> index dfdd3ec5f793..18de1485e2ed 100644
> --- a/drivers/gpu/drm/Kconfig
> +++ b/drivers/gpu/drm/Kconfig
> @@ -405,6 +405,8 @@ source "drivers/gpu/drm/gud/Kconfig"
>
> source "drivers/gpu/drm/sprd/Kconfig"
>
> +source "drivers/gpu/drm/lsdc/Kconfig"
> +
> config DRM_HYPERV
> tristate "DRM Support for Hyper-V synthetic video device"
> depends on DRM && PCI && MMU && HYPERV
> diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile
> index 8675c2af7ae1..2c5a76ced323 100644
> --- a/drivers/gpu/drm/Makefile
> +++ b/drivers/gpu/drm/Makefile
> @@ -133,3 +133,4 @@ obj-y += xlnx/
> obj-y += gud/
> obj-$(CONFIG_DRM_HYPERV) += hyperv/
> obj-$(CONFIG_DRM_SPRD) += sprd/
> +obj-$(CONFIG_DRM_LSDC) += lsdc/
> diff --git a/drivers/gpu/drm/lsdc/Kconfig b/drivers/gpu/drm/lsdc/Kconfig
> new file mode 100644
> index 000000000000..7ed1b0fdbe1b
> --- /dev/null
> +++ b/drivers/gpu/drm/lsdc/Kconfig
> @@ -0,0 +1,38 @@
SPDX (GPL-2.0) needed.
> +config DRM_LSDC
> + tristate "DRM Support for loongson's display controller"
> + depends on DRM && PCI
> + depends on MACH_LOONGSON64 || LOONGARCH || MIPS || COMPILE_TEST
> + select OF
> + select CMA if HAVE_DMA_CONTIGUOUS
> + select DMA_CMA if HAVE_DMA_CONTIGUOUS
> + select DRM_KMS_HELPER
> + select DRM_KMS_FB_HELPER
> + select DRM_GEM_CMA_HELPER
> + select VIDEOMODE_HELPERS
> + select BACKLIGHT_PWM if CPU_LOONGSON2K
> + select I2C_GPIO if CPU_LOONGSON2K
> + select I2C_LS2X if CPU_LOONGSON2K
> + default m
> + help
> + This is a KMS driver for the display controller in the LS7A1000
> + bridge chip and LS2K1000 SoC. The display controller has two
> + display pipes and it is a PCI device.
> + When using this driver on LS2K1000/LS2K0500 SoC, its framebuffer
> + is located at system memory.
> + If "M" is selected, the module will be called lsdc.
> +
> + If in doubt, say "Y".
> +
> +config DRM_LSDC_VRAM_DRIVER
> + bool "vram helper based device driver support"
> + depends on DRM_LSDC
> + select DRM_VRAM_HELPER
> + default y
> + help
> + When using this driver on LS7A1000 + LS3A3000/LS3A4000/LS3A5000
> + platform, the LS7A1000 bridge chip has dedicated video RAM. Using
> + "lsdc.use_vram_helper=1" in the kernel command line will enable
> + this driver mode and then the framebuffer will be located at the
> + VRAM at the price of losing PRIME support.
> +
> + If in doubt, say "Y".
> diff --git a/drivers/gpu/drm/lsdc/Makefile b/drivers/gpu/drm/lsdc/Makefile
> new file mode 100644
> index 000000000000..342990654478
> --- /dev/null
> +++ b/drivers/gpu/drm/lsdc/Makefile
> @@ -0,0 +1,15 @@
SPDX
> +#
> +# Makefile for the lsdc drm device driver.
> +#
> +
> +lsdc-y := \
> + lsdc_drv.o \
> + lsdc_crtc.o \
> + lsdc_irq.o \
> + lsdc_plane.o \
> + lsdc_pll.o \
> + lsdc_i2c.o \
> + lsdc_encoder.o \
> + lsdc_connector.o
> +
> +obj-$(CONFIG_DRM_LSDC) += lsdc.o
> diff --git a/drivers/gpu/drm/lsdc/lsdc_connector.c b/drivers/gpu/drm/lsdc/lsdc_connector.c
> new file mode 100644
> index 000000000000..ae5fc0c90961
> --- /dev/null
> +++ b/drivers/gpu/drm/lsdc/lsdc_connector.c
> @@ -0,0 +1,443 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Copyright 2020 Loongson Corporation
> + *
> + * Permission is hereby granted, free of charge, to any person obtaining a
> + * copy of this software and associated documentation files (the
> + * "Software"), to deal in the Software without restriction, including
> + * without limitation the rights to use, copy, modify, merge, publish,
> + * distribute, sub license, and/or sell copies of the Software, and to
> + * permit persons to whom the Software is furnished to do so, subject to
> + * the following conditions:
> + *
> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
> + * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
> + * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
> + * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
> + * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
> + * USE OR OTHER DEALINGS IN THE SOFTWARE.
> + *
> + * The above copyright notice and this permission notice (including the
> + * next paragraph) shall be included in all copies or substantial portions
> + * of the Software.
This does not look like compliant with GPL-2.0. You cannot call a
license GPL-2.0 and restrict it with some other provisions.
Please fix the licensing.
> + */
> +
> +/*
> + * Authors:
> + * Sui Jingfeng <suijingfeng@...ngson.cn>
> + */
> +
> +#include <drm/drm_print.h>
> +#include <drm/drm_edid.h>
> +#include <drm/drm_probe_helper.h>
> +#include <drm/drm_atomic_helper.h>
> +#include <drm/drm_crtc_helper.h>
> +#include <drm/drm_connector.h>
> +
> +#include <video/videomode.h>
> +#include <video/of_display_timing.h>
> +
> +#include "lsdc_drv.h"
> +#include "lsdc_i2c.h"
> +#include "lsdc_connector.h"
> +
> +
> +static int lsdc_get_modes_from_edid(struct drm_connector *connector)
> +{
> + struct drm_device *ddev = connector->dev;
> + struct lsdc_connector *lconn = to_lsdc_connector(connector);
> + struct edid *edid_p = (struct edid *)lconn->edid_data;
> + int num = drm_add_edid_modes(connector, edid_p);
> +
> + if (num)
> + drm_connector_update_edid_property(connector, edid_p);
> +
> + drm_dbg_kms(ddev, "%d modes added\n", num);
> +
> + return num;
> +}
> +
> +
Do not use double blank lines. Single line. Here and in all other places.
Best regards,
Krzysztof
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