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

[Stefan Demharter <stefan.demharter@gmx.net>]

On 2014-09-05 13:28, Jani Nikula wrote:
> On Fri, 31 Jan 2014, Alex Deucher <alexdeucher@gmail.com> wrote:
>> On Thu, Jan 30, 2014 at 6:46 PM, Stefan Demharter
>> <stefan.demharter@gmx.net> 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@gmx.net>
>>
>> Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
> 
> Despite the review, looks like this one has fallen between the
> cracks. There's some comments from Chris at [1].
> 
> Dave?
> 
> 
> BR,
> Jani.
> 
> [1] https://bugs.freedesktop.org/show_bug.cgi?id=70863#c4

sorry for the late response.
But here are my thoughts/answers to the points mentioned by Chris:

1. I will provide an updated patch which has the description in the changelog very soon.
2. I just want to set the gpu state to the power state the system thinks the gpu is in,
   so I don't think this is necessary and may also have other side effects.
3./4. As the mux is actually always in a valid state I've removed the
   undefined state in the updated patch.
   It is assumed that the mux is initially set to MIGD.
   The logic should also work with mux-less systems.
   For details please look into the updated patch.

Regards,
Stefan

> 
>>
>>> ---
>>>  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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