There is a display controller in loongson's LS2K1000 SoC and LS7A1000 bridge chip, the display controller is a PCI device. It have two display pipes but with only one hardware cursor. Each way has a DVO interface which provide RGB888 signals, vertical & horizontal synchronisations, data enable and the pixel clock.
Each CRTC is able to drive a 1920x1080@60Hz monitor, the maxmium resolution is 2048x2048. Loongson display controllers are simple which require scanout buffers to be physically contiguous.
For LS7A1000 bridge chip, the DC is equipped with a dedicated video RAM which is typically 64MB or more. In this case, VRAM helper based driver is intended to be used even through the DC can scanout form system memory.
While LS2K1000 is a SoC which is a typically UMA device, only system memory is available. Therefore CMA helper based driver is intended to be used. It is possible to use VRAM helper based driver on LS2K1000 by carving out part of system memory as VRAM though.
For LS7A1000, there are 4 dedicated GPIOs whose control registers is located at the DC register space, They are used to emulate two way i2c. One for DVO0, another for DVO1. LS2K1000 and LS2K0500 SoC don't have such GPIO hardwared, they grab i2c adapter from other module, either general purpose GPIO emulated i2c or hardware i2c adapter.
+------+ +-----------------------------------+ | DDR4 | | +-------------------+ | +------+ | | PCIe Root complex | LS7A1000 | || MC0 | +--++---------++----+ | +----------+ HT 3.0 | || || | | LS3A4000 |<-------->| +---++---+ +--++--+ +---------+ +------+ | CPU |<-------->| | GC1000 | | LSDC |<-->| DDR3 MC |<->| VRAM | +----------+ | +--------+ +-+--+-+ +---------+ +------+ || 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, other candicates can be ch7034b, sil9022, ite66121 and lt8618 etc.
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[3]. LS3A5000 is 4 core 2.5gHz loongarch cpu[4].
Nearly all loongson cpu has the hardware maintain the cache coherency, this is the most distinct feature from other Mips cpu.
[1] https://wiki.debian.org/InstallingDebianOn/Lemote/Loongson2K1000 [2] https://loongson.github.io/LoongArch-Documentation/Loongson-7A1000-usermanua... [3] https://ee-paper.com/loongson-3a4000-3b4000-motherboard-products-are-compati... [4] https://loongson.github.io/LoongArch-Documentation/Loongson-3A5000-usermanua... [5] https://github.com/loongson-community/pmon
Sui Jingfeng (6): MIPS: Loongson64: dts: update the display controller device node MIPS: Loongson64: introduce board specific dts and add model property dt-bindings: display: Add Loongson display controller MIPS: Loongson64: defconfig: enable display bridge drivers drm/loongson: add drm driver for loongson display controller MAINTAINERS: add maintainers for DRM LOONGSON driver
.../loongson/loongson,display-controller.yaml | 289 +++++++++ MAINTAINERS | 9 + arch/mips/boot/dts/loongson/Makefile | 4 + arch/mips/boot/dts/loongson/lemote_a1901.dts | 96 +++ .../boot/dts/loongson/loongson64-2k1000.dtsi | 8 + .../boot/dts/loongson/ls2k1000_pai_udb.dts | 107 ++++ .../boot/dts/loongson/ls3a4000_7a1000_evb.dts | 138 +++++ arch/mips/boot/dts/loongson/ls7a-pch.dtsi | 22 +- arch/mips/configs/loongson2k_defconfig | 5 + arch/mips/configs/loongson3_defconfig | 5 + drivers/gpu/drm/Kconfig | 2 + drivers/gpu/drm/Makefile | 1 + drivers/gpu/drm/loongson/Kconfig | 25 + drivers/gpu/drm/loongson/Makefile | 16 + drivers/gpu/drm/loongson/lsdc_crtc.c | 400 ++++++++++++ drivers/gpu/drm/loongson/lsdc_debugfs.c | 176 ++++++ drivers/gpu/drm/loongson/lsdc_debugfs.h | 17 + drivers/gpu/drm/loongson/lsdc_drv.c | 413 +++++++++++++ drivers/gpu/drm/loongson/lsdc_drv.h | 186 ++++++ drivers/gpu/drm/loongson/lsdc_i2c.c | 268 ++++++++ drivers/gpu/drm/loongson/lsdc_i2c.h | 38 ++ drivers/gpu/drm/loongson/lsdc_irq.c | 57 ++ drivers/gpu/drm/loongson/lsdc_irq.h | 17 + drivers/gpu/drm/loongson/lsdc_output.c | 261 ++++++++ drivers/gpu/drm/loongson/lsdc_output.h | 21 + drivers/gpu/drm/loongson/lsdc_pci_drv.c | 342 +++++++++++ drivers/gpu/drm/loongson/lsdc_plane.c | 436 +++++++++++++ drivers/gpu/drm/loongson/lsdc_pll.c | 573 ++++++++++++++++++ drivers/gpu/drm/loongson/lsdc_pll.h | 87 +++ drivers/gpu/drm/loongson/lsdc_regs.h | 219 +++++++ 30 files changed, 4233 insertions(+), 5 deletions(-) create mode 100644 Documentation/devicetree/bindings/display/loongson/loongson,display-controller.yaml create mode 100644 arch/mips/boot/dts/loongson/lemote_a1901.dts create mode 100644 arch/mips/boot/dts/loongson/ls2k1000_pai_udb.dts create mode 100644 arch/mips/boot/dts/loongson/ls3a4000_7a1000_evb.dts create mode 100644 drivers/gpu/drm/loongson/Kconfig create mode 100644 drivers/gpu/drm/loongson/Makefile create mode 100644 drivers/gpu/drm/loongson/lsdc_crtc.c create mode 100644 drivers/gpu/drm/loongson/lsdc_debugfs.c create mode 100644 drivers/gpu/drm/loongson/lsdc_debugfs.h create mode 100644 drivers/gpu/drm/loongson/lsdc_drv.c create mode 100644 drivers/gpu/drm/loongson/lsdc_drv.h create mode 100644 drivers/gpu/drm/loongson/lsdc_i2c.c create mode 100644 drivers/gpu/drm/loongson/lsdc_i2c.h create mode 100644 drivers/gpu/drm/loongson/lsdc_irq.c create mode 100644 drivers/gpu/drm/loongson/lsdc_irq.h create mode 100644 drivers/gpu/drm/loongson/lsdc_output.c create mode 100644 drivers/gpu/drm/loongson/lsdc_output.h create mode 100644 drivers/gpu/drm/loongson/lsdc_pci_drv.c create mode 100644 drivers/gpu/drm/loongson/lsdc_plane.c create mode 100644 drivers/gpu/drm/loongson/lsdc_pll.c create mode 100644 drivers/gpu/drm/loongson/lsdc_pll.h create mode 100644 drivers/gpu/drm/loongson/lsdc_regs.h