Re: [PATCH RFC v2] vga_switcheroo: restore mux and power states upon resume from hibernation.

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On Thu, Jan 30, 2014 at 6:46 PM, Stefan Demharter
<stefan.demharter@xxxxxxx> wrote:
> Saves the current state of the mux and restores it upon resume from hibernation.
> This is needed for muxed systems because the state of the mux doesn't survive a
> hibernation-resume cycle. Furthermore also restores the power state of a GPU
> to OFF after resume from hibernation if it was OFF before hibernation.
>
> Signed-off-by: Stefan Demharter <stefan.demharter@xxxxxxx>

Reviewed-by: Alex Deucher <alexander.deucher@xxxxxxx>

> ---
>  drivers/gpu/vga/vga_switcheroo.c | 96 +++++++++++++++++++++++++++++++++++-----
>  1 file changed, 85 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/gpu/vga/vga_switcheroo.c b/drivers/gpu/vga/vga_switcheroo.c
> index ec0ae2d..85f41b9 100644
> --- a/drivers/gpu/vga/vga_switcheroo.c
> +++ b/drivers/gpu/vga/vga_switcheroo.c
> @@ -28,6 +28,7 @@
>  #include <linux/console.h>
>  #include <linux/vga_switcheroo.h>
>  #include <linux/pm_runtime.h>
> +#include <linux/suspend.h>
>
>  #include <linux/vgaarb.h>
>
> @@ -72,6 +73,64 @@ static struct vgasr_priv vgasr_priv = {
>         .clients = LIST_HEAD_INIT(vgasr_priv.clients),
>  };
>
> +#define MUX_STATE_UNDEFINED (-1)
> +/*
> + * The next variable stores the state of the mux
> + * so it can be restored upon resume from hibernation.
> + */
> +static int mux_state = MUX_STATE_UNDEFINED;
> +
> +static void vga_restore_mux(void)
> +{
> +       if (mux_state != MUX_STATE_UNDEFINED) {
> +               int ret;
> +               pr_info("vga_switcheroo: restoring mux state to %s\n",
> +                       mux_state == VGA_SWITCHEROO_IGD ? "IGD" : "DIS");
> +
> +               ret = vgasr_priv.handler->switchto(mux_state);
> +               if (ret)
> +                       pr_warn("vga_switcheroo: mux switch failed (%d)\n", ret);
> +       }
> +}
> +
> +static void vga_restore_power_state(void)
> +{
> +       struct vga_switcheroo_client *client;
> +
> +       if (!vgasr_priv.handler->power_state)
> +               return;
> +
> +       list_for_each_entry(client, &vgasr_priv.clients, list) {
> +               if (client_is_vga(client) && client->pwr_state == VGA_SWITCHEROO_OFF) {
> +                       pr_info("vga_switcheroo: setting power state of %s to OFF\n",
> +                               client->id == VGA_SWITCHEROO_IGD ? "IGD" : "DIS");
> +                       vgasr_priv.handler->power_state(client->id, client->pwr_state);
> +               }
> +       }
> +}
> +
> +/*
> + * Handle resume from hibernation:
> + * Restore mux state and power states for switcheroo controlled GPUs.
> + */
> +static int vga_resume(struct notifier_block *nb, unsigned long action, void *unused)
> +{
> +       switch (action) {
> +       case PM_POST_HIBERNATION:
> +               mutex_lock(&vgasr_mutex);
> +               vga_restore_mux();
> +               vga_restore_power_state();
> +               mutex_unlock(&vgasr_mutex);
> +               break;
> +       }
> +       return 0;
> +}
> +
> +static struct notifier_block vga_switcheroo_pm_nb = {
> +       .notifier_call = vga_resume,
> +       .priority = 0,
> +};
> +
>  static bool vga_switcheroo_ready(void)
>  {
>         /* we're ready if we get two clients + handler */
> @@ -84,6 +143,8 @@ static void vga_switcheroo_enable(void)
>         int ret;
>         struct vga_switcheroo_client *client;
>
> +       pr_info("vga_switcheroo: enabled\n");
> +
>         /* call the handler to init */
>         if (vgasr_priv.handler->init)
>                 vgasr_priv.handler->init();
> @@ -99,6 +160,15 @@ static void vga_switcheroo_enable(void)
>         }
>         vga_switcheroo_debugfs_init(&vgasr_priv);
>         vgasr_priv.active = true;
> +       register_pm_notifier(&vga_switcheroo_pm_nb);
> +}
> +
> +void vga_switcheroo_disable(void)
> +{
> +       unregister_pm_notifier(&vga_switcheroo_pm_nb);
> +       vgasr_priv.active = false;
> +       vga_switcheroo_debugfs_fini(&vgasr_priv);
> +       pr_info("vga_switcheroo: disabled\n");
>  }
>
>  int vga_switcheroo_register_handler(struct vga_switcheroo_handler *handler)
> @@ -111,7 +181,6 @@ int vga_switcheroo_register_handler(struct vga_switcheroo_handler *handler)
>
>         vgasr_priv.handler = handler;
>         if (vga_switcheroo_ready()) {
> -               printk(KERN_INFO "vga_switcheroo: enabled\n");
>                 vga_switcheroo_enable();
>         }
>         mutex_unlock(&vgasr_mutex);
> @@ -124,9 +193,7 @@ void vga_switcheroo_unregister_handler(void)
>         mutex_lock(&vgasr_mutex);
>         vgasr_priv.handler = NULL;
>         if (vgasr_priv.active) {
> -               pr_info("vga_switcheroo: disabled\n");
> -               vga_switcheroo_debugfs_fini(&vgasr_priv);
> -               vgasr_priv.active = false;
> +               vga_switcheroo_disable();
>         }
>         mutex_unlock(&vgasr_mutex);
>  }
> @@ -155,7 +222,6 @@ static int register_client(struct pci_dev *pdev,
>                 vgasr_priv.registered_clients++;
>
>         if (vga_switcheroo_ready()) {
> -               printk(KERN_INFO "vga_switcheroo: enabled\n");
>                 vga_switcheroo_enable();
>         }
>         mutex_unlock(&vgasr_mutex);
> @@ -235,9 +301,7 @@ void vga_switcheroo_unregister_client(struct pci_dev *pdev)
>                 kfree(client);
>         }
>         if (vgasr_priv.active && vgasr_priv.registered_clients < 2) {
> -               printk(KERN_INFO "vga_switcheroo: disabled\n");
> -               vga_switcheroo_debugfs_fini(&vgasr_priv);
> -               vgasr_priv.active = false;
> +               vga_switcheroo_disable();
>         }
>         mutex_unlock(&vgasr_mutex);
>  }
> @@ -262,10 +326,11 @@ static int vga_switcheroo_show(struct seq_file *m, void *v)
>         int i = 0;
>         mutex_lock(&vgasr_mutex);
>         list_for_each_entry(client, &vgasr_priv.clients, list) {
> -               seq_printf(m, "%d:%s%s:%c:%s%s:%s\n", i,
> +               seq_printf(m, "%d:%s%s:%c%s:%s%s:%s\n", i,
>                            client_id(client) == VGA_SWITCHEROO_DIS ? "DIS" : "IGD",
>                            client_is_vga(client) ? "" : "-Audio",
>                            client->active ? '+' : ' ',
> +                          client_id(client) == mux_state ? "mux" : "",
>                            client->driver_power_control ? "Dyn" : "",
>                            client->pwr_state ? "Pwr" : "Off",
>                            pci_name(client->pdev));
> @@ -304,6 +369,15 @@ static int vga_switchoff(struct vga_switcheroo_client *client)
>         return 0;
>  }
>
> +static int vga_switchto(int client_id)
> +{
> +       int ret = vgasr_priv.handler->switchto(client_id);
> +
> +       if (ret == 0)
> +               mux_state = client_id;
> +       return ret;
> +}
> +
>  static void set_audio_state(int id, int state)
>  {
>         struct vga_switcheroo_client *client;
> @@ -353,7 +427,7 @@ static int vga_switchto_stage2(struct vga_switcheroo_client *new_client)
>                 console_unlock();
>         }
>
> -       ret = vgasr_priv.handler->switchto(new_client->id);
> +       ret = vga_switchto(new_client->id);
>         if (ret)
>                 return ret;
>
> @@ -468,7 +542,7 @@ vga_switcheroo_debugfs_write(struct file *filp, const char __user *ubuf,
>         vgasr_priv.delayed_switch_active = false;
>
>         if (just_mux) {
> -               ret = vgasr_priv.handler->switchto(client_id);
> +               ret = vga_switchto(client_id);
>                 goto out;
>         }
>
> --
> 1.8.5.3
>
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