On Mon, Jan 04, 2016 at 12:21:40PM -0800, Darren Hart wrote: > On Mon, Jan 04, 2016 at 05:52:06PM +0100, Lukas Wunner wrote: > > Document what I've learned so far about the gmux so that we can > > collaboratively reverse-engineer its remaining unknown bits > > without everyone having to start from scratch. > > > > +Jon Corbet > +Daniel Vetter > +linux-doc > > Any concerns with this series? If not, I'll take it in via the pdx86 tree. Acked-by: Daniel Vetter <daniel.vetter@xxxxxxxx> Like Jonathan clarified asciidoc is purely optional, at most it'll look a bit funny with the upstream docbook system. -Daniel > > Thanks, > > Darren > > > The DOC sections are bound together in the gpu.tmpl DocBook > > under a new vga_switcheroo "Handlers" chapter. Eventually > > this should be amended with documentation about the four other > > handlers that exist so far (nouveau v1 DSM, nouveau Optimus DSM, > > radeon ATPX, amdgpu ATPX). > > > > Requires kernel-doc with asciidoc support. > > > > The EFI variable was reverse-engineered by Bruno Bierbaumer > > <bruno@xxxxxxxxxxxxxx> and Andreas Heider <andreas@xxxxxxxx>. > > > > Some of the remaining open questions: > > > > * How are vblank intervals synchronized on retinas to achieve seamless > > switching? Is the DP mux capable of this? It's not mentioned in the > > data sheets. Or is it done at the OS level, i.e. do we have to > > synchronize vblank intervals between DRM drivers? There's a signal > > coming from the panel connector and going into gmux, could this be > > the vblank signal as received by the panel to properly time the > > switch? > > > > * On retinas there's an I2C bus between gmux and the connector of the > > right I/O board, apparently leading to the Parade PS8401A HDMI > > repeater. What is this for, is it controlled via gmux registers? > > Data sheet: > > http://www.paradetech.com/products/jitter-cleaning-repeaters/ps8401/ > > > > * On retinas there's an I2C bus between gmux and the LED driver. > > Pre-retinas connected the LED driver to SMBUS. Are there additional > > gmux registers on retinas to control it? > > > > * The MacPro6,1 2013 also has a gmux, the same Renesas R4F2113 as the > > retina MacBook Pro. The Mac Pro doesn't have a built-in display, > > so what is its purpose? Power control of the dual FirePro GPUs? > > Switching of the external DP/Thunderbolt ports? The iFixit teardown > > clearly shows one TI HD3SS212 DisplayPort mux on the logic board next > > to one of the three Thunderbolt controllers. However six muxes would > > be necessary to switch all six ports between GPUs. The mux is probably > > necessary for one of the display configurations allowed by Apple, > > but which one? > > https://www.ifixit.com/Teardown/Mac+Pro+Late+2013+Teardown/20778 > > https://d3nevzfk7ii3be.cloudfront.net/igi/fELBTnt31QhnDsqq.huge > > https://support.apple.com/en-us/HT202801 > > > > * Registers we haven't decoded yet: > > 0x700 32 Bit configmap? > > 0x708 32 Bit power sequence? > > 0x712 8 Bit status of clock from panel on retinas? > > 0x713 8 Bit dito? > > 0x724 16 Bit backlight, raw value? > > 0x760 32 Bit backlight > > 0x764 32 Bit backlight > > 0x768 8 Bit backlight > > 0x76a 16 Bit backlight > > 0x76c 16 Bit backlight > > 0x76e 16 Bit backlight > > 0x77f edp/dp/hdmi probe? retina only. > > > > Signed-off-by: Lukas Wunner <lukas@xxxxxxxxx> > > --- > > Documentation/DocBook/gpu.tmpl | 22 ++++++++ > > drivers/platform/x86/apple-gmux.c | 113 ++++++++++++++++++++++++++++++++++++++ > > 2 files changed, 135 insertions(+) > > > > diff --git a/Documentation/DocBook/gpu.tmpl b/Documentation/DocBook/gpu.tmpl > > index 225a246..9e95aa1 100644 > > --- a/Documentation/DocBook/gpu.tmpl > > +++ b/Documentation/DocBook/gpu.tmpl > > @@ -3658,8 +3658,30 @@ int num_ioctls;</synopsis> > > </sect1> > > </chapter> > > > > + <chapter id="handlers"> > > + <title>Handlers</title> > > + <sect1> > > + <title>apple-gmux Handler</title> > > +!Pdrivers/platform/x86/apple-gmux.c Overview > > +!Pdrivers/platform/x86/apple-gmux.c Interrupt > > + <sect2> > > + <title>Graphics mux</title> > > +!Pdrivers/platform/x86/apple-gmux.c Graphics mux > > + </sect2> > > + <sect2> > > + <title>Power control</title> > > +!Pdrivers/platform/x86/apple-gmux.c Power control > > + </sect2> > > + <sect2> > > + <title>Backlight control</title> > > +!Pdrivers/platform/x86/apple-gmux.c Backlight control > > + </sect2> > > + </sect1> > > + </chapter> > > + > > !Cdrivers/gpu/vga/vga_switcheroo.c > > !Cinclude/linux/vga_switcheroo.h > > +!Cdrivers/platform/x86/apple-gmux.c > > </part> > > > > </book> > > diff --git a/drivers/platform/x86/apple-gmux.c b/drivers/platform/x86/apple-gmux.c > > index aa58d41..f236250 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@xxxxxxxxxxxxx> > > * Copyright (C) 2010-2012 Andreas Heider <andreas@xxxxxxxx> > > + * Copyright (C) 2015 Lukas Wunner <lukas@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 > > @@ -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, > > -- > > 1.8.5.2 (Apple Git-48) > > > > -- > > To unsubscribe from this list: send the line "unsubscribe platform-driver-x86" in > > the body of a message to majordomo@xxxxxxxxxxxxxxx > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > > > -- > Darren Hart > Intel Open Source Technology Center -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch -- To unsubscribe from this list: send the line "unsubscribe platform-driver-x86" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
