[PATCH v4 2/6] apple-gmux: Add switch_ddc support

[Alex Deucher]

On Fri, Aug 14, 2015 at 12:18 PM, Lukas Wunner <lukas at wunner.de> wrote:
> Originally by Seth Forshee <seth.forshee at canonical.com>, 2012-10-04:
>     The gmux allows muxing the DDC independently from the display, so
>     support this functionality. This will allow reading the EDID for the
>     inactive GPU, fixing issues with machines that either don't have a
>     VBT or have invalid mode data in the VBT.
>
> Modified by Lukas Wunner <lukas at wunner.de>, 2015-10-07:
>     Advertise ->switch_ddc handler callback only on the pre-retina
>     Macbook Pro. The retina uses eDP and its mux is incapable of
>     switching the AUX channel separately from the main link.
>     It's an NXP CBTL06142 (alternate parts: TI HD3SS212,
>     Pericom PPI3VDP12412).
>
>     Sources:
>     http://www.electronicproducts.com/-whatsinside_text-145.aspx
>     http://slideshare.net/jjwu6266/apple-2012-wwdc-apple-macbook-pro-with-retina-display
>     http://www.techrepublic.com/blog/cracking-open/teardown-shows-retina-macbook-pro-is-nearly-impossible-to-upgrade-difficult-to-work-on/
>
>     Datasheets:
>     http://www.nxp.com/documents/data_sheet/CBTL06141.pdf
>     http://www.ti.com/lit/ds/symlink/hd3ss212.pdf
>     https://www.pericom.com/assets/Datasheets/PI3VDP12412.pdf
>
> Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=88861
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=61115
> Tested-by: Lukas Wunner <lukas at wunner.de>
>     [MBP  9,1 2012  intel IVB + nvidia GK107  pre-retina  15"]
>
> Cc: Seth Forshee <seth.forshee at canonical.com>
> Signed-off-by: Lukas Wunner <lukas at wunner.de>
> ---
>  drivers/platform/x86/apple-gmux.c | 21 +++++++++++++++++++--
>  1 file changed, 19 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/platform/x86/apple-gmux.c b/drivers/platform/x86/apple-gmux.c
> index 0dec3f5..78997b7 100644
> --- a/drivers/platform/x86/apple-gmux.c
> +++ b/drivers/platform/x86/apple-gmux.c
> @@ -276,11 +276,9 @@ static const struct backlight_ops gmux_bl_ops = {
>  static int gmux_switchto(enum vga_switcheroo_client_id id)
>  {
>         if (id == VGA_SWITCHEROO_IGD) {
> -               gmux_write8(apple_gmux_data, GMUX_PORT_SWITCH_DDC, 1);
>                 gmux_write8(apple_gmux_data, GMUX_PORT_SWITCH_DISPLAY, 2);
>                 gmux_write8(apple_gmux_data, GMUX_PORT_SWITCH_EXTERNAL, 2);
>         } else {
> -               gmux_write8(apple_gmux_data, GMUX_PORT_SWITCH_DDC, 2);
>                 gmux_write8(apple_gmux_data, GMUX_PORT_SWITCH_DISPLAY, 3);
>                 gmux_write8(apple_gmux_data, GMUX_PORT_SWITCH_EXTERNAL, 3);
>         }

Won't this hunk break manual switching until the later patches land?
Seems like you might want to break this out as a separate patch later
in the series.

Alex


> @@ -288,6 +286,18 @@ static int gmux_switchto(enum vga_switcheroo_client_id id)
>         return 0;
>  }
>
> +static int gmux_switch_ddc(enum vga_switcheroo_client_id id)
> +{
> +       pr_debug("Switching gmux DDC to %d\n", id);
> +
> +       if (id == VGA_SWITCHEROO_IGD)
> +               gmux_write8(apple_gmux_data, GMUX_PORT_SWITCH_DDC, 1);
> +       else
> +               gmux_write8(apple_gmux_data, GMUX_PORT_SWITCH_DDC, 2);
> +
> +       return 0;
> +}
> +
>  static int gmux_set_discrete_state(struct apple_gmux_data *gmux_data,
>                                    enum vga_switcheroo_state state)
>  {
> @@ -588,6 +598,13 @@ static int gmux_probe(struct pnp_dev *pnp, const struct pnp_device_id *id)
>                 gmux_data->gpe = -1;
>         }
>
> +       /*
> +        * The gmux in pre-retina MacBook Pros can switch DDC separately
> +        * from the other pins of the outputs. It's distinguishable from
> +        * the gmux in retinas by being non-indexed.
> +        */
> +       if (!gmux_data->indexed)
> +               gmux_handler.switch_ddc = gmux_switch_ddc;
>         if (vga_switcheroo_register_handler(&gmux_handler)) {
>                 ret = -ENODEV;
>                 goto err_register_handler;
> --
> 1.8.5.2 (Apple Git-48)
>
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