diff options
Diffstat (limited to 'drivers/platform/x86/apple-gmux.c')
| -rw-r--r-- | drivers/platform/x86/apple-gmux.c | 123 |
1 files changed, 119 insertions, 4 deletions
diff --git a/drivers/platform/x86/apple-gmux.c b/drivers/platform/x86/apple-gmux.c index 976efeb3f2ba..f236250ac106 100644 --- a/drivers/platform/x86/apple-gmux.c +++ b/drivers/platform/x86/apple-gmux.c @@ -3,6 +3,7 @@ * * Copyright (C) Canonical Ltd. <seth.forshee@canonical.com> * Copyright (C) 2010-2012 Andreas Heider <andreas@meetr.de> + * Copyright (C) 2015 Lukas Wunner <lukas@wunner.de> * * 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 @@ -26,6 +27,24 @@ #include <acpi/video.h> #include <asm/io.h> +/** + * DOC: Overview + * + * :1: http://www.latticesemi.com/en/Products/FPGAandCPLD/LatticeXP2.aspx + * :2: http://www.renesas.com/products/mpumcu/h8s/h8s2100/h8s2113/index.jsp + * + * gmux is a microcontroller built into the MacBook Pro to support dual GPUs: + * A {1}[Lattice XP2] on pre-retinas, a {2}[Renesas R4F2113] on retinas. + * + * (The MacPro6,1 2013 also has a gmux, however it is unclear why since it has + * dual GPUs but no built-in display.) + * + * gmux is connected to the LPC bus of the southbridge. Its I/O ports are + * accessed differently depending on the microcontroller: Driver functions + * to access a pre-retina gmux are infixed `_pio_`, those for a retina gmux + * are infixed `_index_`. + */ + struct apple_gmux_data { unsigned long iostart; unsigned long iolen; @@ -247,6 +266,20 @@ static bool gmux_is_indexed(struct apple_gmux_data *gmux_data) return false; } +/** + * DOC: Backlight control + * + * :3: http://www.ti.com/lit/ds/symlink/lp8543.pdf + * :4: http://www.ti.com/lit/ds/symlink/lp8545.pdf + * + * On single GPU MacBooks, the PWM signal for the backlight is generated by + * the GPU. On dual GPU MacBook Pros by contrast, either GPU may be suspended + * to conserve energy. Hence the PWM signal needs to be generated by a separate + * backlight driver which is controlled by gmux. The earliest generation + * MBP5 2008/09 uses a {3}[TI LP8543] backlight driver. All newer models + * use a {4}[TI LP8545]. + */ + static int gmux_get_brightness(struct backlight_device *bd) { struct apple_gmux_data *gmux_data = bl_get_data(bd); @@ -273,6 +306,68 @@ static const struct backlight_ops gmux_bl_ops = { .update_status = gmux_update_status, }; +/** + * DOC: Graphics mux + * + * :5: http://pimg-fpiw.uspto.gov/fdd/07/870/086/0.pdf + * :6: http://www.nxp.com/documents/data_sheet/CBTL06141.pdf + * :7: http://www.ti.com/lit/ds/symlink/hd3ss212.pdf + * :8: https://www.pericom.com/assets/Datasheets/PI3VDP12412.pdf + * :9: http://www.ti.com/lit/ds/symlink/sn74lv4066a.pdf + * :10: http://pdf.datasheetarchive.com/indexerfiles/Datasheets-SW16/DSASW00308511.pdf + * :11: http://www.ti.com/lit/ds/symlink/ts3ds10224.pdf + * + * On pre-retinas, the LVDS outputs of both GPUs feed into gmux which muxes + * either of them to the panel. One of the tricks gmux has up its sleeve is + * to lengthen the blanking interval of its output during a switch to + * synchronize it with the GPU switched to. This allows for a flicker-free + * switch that is imperceptible by the user ({5}[US 8,687,007 B2]). + * + * On retinas, muxing is no longer done by gmux itself, but by a separate + * chip which is controlled by gmux. The chip is triple sourced, it is + * either an {6}[NXP CBTL06142], {7}[TI HD3SS212] or {8}[Pericom PI3VDP12412]. + * The panel is driven with eDP instead of LVDS since the pixel clock + * required for retina resolution exceeds LVDS' limits. + * + * Pre-retinas are able to switch the panel's DDC pins separately. + * This is handled by a {9}[TI SN74LV4066A] which is controlled by gmux. + * The inactive GPU can thus probe the panel's EDID without switching over + * the entire panel. Retinas lack this functionality as the chips used for + * eDP muxing are incapable of switching the AUX channel separately (see + * the linked data sheets, Pericom would be capable but this is unused). + * However the retina panel has the NO_AUX_HANDSHAKE_LINK_TRAINING bit set + * in its DPCD, allowing the inactive GPU to skip the AUX handshake and + * set up the output with link parameters pre-calibrated by the active GPU. + * + * The external DP port is only fully switchable on the first two unibody + * MacBook Pro generations, MBP5 2008/09 and MBP6 2010. This is done by an + * {6}[NXP CBTL06141] which is controlled by gmux. It's the predecessor of the + * eDP mux on retinas, the difference being support for 2.7 versus 5.4 Gbit/s. + * + * The following MacBook Pro generations replaced the external DP port with a + * combined DP/Thunderbolt port and lost the ability to switch it between GPUs, + * connecting it either to the discrete GPU or the Thunderbolt controller. + * Oddly enough, while the full port is no longer switchable, AUX and HPD + * are still switchable by way of an {10}[NXP CBTL03062] (on pre-retinas + * MBP8 2011 and MBP9 2012) or two {11}[TI TS3DS10224] (on retinas) under the + * control of gmux. Since the integrated GPU is missing the main link, + * external displays appear to it as phantoms which fail to link-train. + * + * gmux receives the HPD signal of all display connectors and sends an + * interrupt on hotplug. On generations which cannot switch external ports, + * the discrete GPU can then be woken to drive the newly connected display. + * The ability to switch AUX on these generations could be used to improve + * reliability of hotplug detection by having the integrated GPU poll the + * ports while the discrete GPU is asleep, but currently we do not make use + * of this feature. + * + * gmux' initial switch state on bootup is user configurable via the EFI + * variable `gpu-power-prefs-fa4ce28d-b62f-4c99-9cc3-6815686e30f9` (5th byte, + * 1 = IGD, 0 = DIS). Based on this setting, the EFI firmware tells gmux to + * switch the panel and the external DP connector and allocates a framebuffer + * for the selected GPU. + */ + static int gmux_switchto(enum vga_switcheroo_client_id id) { if (id == VGA_SWITCHEROO_IGD) { @@ -288,6 +383,14 @@ static int gmux_switchto(enum vga_switcheroo_client_id id) return 0; } +/** + * DOC: Power control + * + * gmux is able to cut power to the discrete GPU. It automatically takes care + * of the correct sequence to tear down and bring up the power rails for + * core voltage, VRAM and PCIe. + */ + static int gmux_set_discrete_state(struct apple_gmux_data *gmux_data, enum vga_switcheroo_state state) { @@ -352,6 +455,16 @@ static const struct vga_switcheroo_handler gmux_handler = { .get_client_id = gmux_get_client_id, }; +/** + * DOC: Interrupt + * + * gmux is also connected to a GPIO pin of the southbridge and thereby is able + * to trigger an ACPI GPE. On the MBP5 2008/09 it's GPIO pin 22 of the Nvidia + * MCP79, on all following generations it's GPIO pin 6 of the Intel PCH. + * The GPE merely signals that an interrupt occurred, the actual type of event + * is identified by reading a gmux register. + */ + static inline void gmux_disable_interrupts(struct apple_gmux_data *gmux_data) { gmux_write8(gmux_data, GMUX_PORT_INTERRUPT_ENABLE, @@ -588,18 +701,20 @@ static int gmux_probe(struct pnp_dev *pnp, const struct pnp_device_id *id) gmux_data->gpe = -1; } + apple_gmux_data = gmux_data; + init_completion(&gmux_data->powerchange_done); + gmux_enable_interrupts(gmux_data); + if (vga_switcheroo_register_handler(&gmux_handler)) { ret = -ENODEV; goto err_register_handler; } - init_completion(&gmux_data->powerchange_done); - apple_gmux_data = gmux_data; - gmux_enable_interrupts(gmux_data); - return 0; err_register_handler: + gmux_disable_interrupts(gmux_data); + apple_gmux_data = NULL; if (gmux_data->gpe >= 0) acpi_disable_gpe(NULL, gmux_data->gpe); err_enable_gpe: |