linux-kernel - Re: [PATCH v4] Support intel-vbtn based tablet mode switch

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Date:   Fri, 26 Jan 2018 12:16:52 +0100
From:   Pali Rohár <pali.rohar@...il.com>
To:     Marco Martin <notmart@...il.com>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Matthew Garrett <mjg59@...f.ucam.org>,
        Darren Hart <dvhart@...radead.org>,
        Andy Shevchenko <andy@...radead.org>,
        Bhushan Shah <bhush94@...il.com>,
        Platform Driver <platform-driver-x86@...r.kernel.org>,
        Mario Limonciello <mario.limonciello@...l.com>,
        Mario Limonciello <mario_limonciello@...l.com>
Subject: Re: [PATCH v4] Support intel-vbtn based tablet mode switch

On Friday 26 January 2018 12:09:01 Marco Martin wrote:
> On Fri, Jan 26, 2018 at 11:52 AM, Pali Rohár <pali.rohar@...il.com> wrote:
> > On Friday 26 January 2018 10:45:55 Marco Martin wrote:
> >> On martedì 23 gennaio 2018 16:18:24 CET Marco Martin wrote:
> >> > Some laptops such as Dell Inspiron 7000 series have the
> >> > tablet mode switch implemented in Intel ACPI,
> >> > the events to enter and exit the tablet mode are 0xCC and 0xCD
> >> >
> >> > CC: platform-driver-x86@...r.kernel.org
> >> > CC: Matthew Garrett <mjg59@...f.ucam.org>
> >> > CC: "Pali Rohár" <pali.rohar@...il.com>
> >> > CC: Darren Hart <dvhart@...radead.org>
> >> > CC: Mario Limonciello <mario_limonciello@...l.com>
> >> > CC: Andy Shevchenko <andy@...radead.org>
> >> >
> >> > Signed-off-by: Marco Martin <notmart@...il.com>
> >> > ---
> >> >  drivers/platform/x86/intel-vbtn.c | 21 +++++++++++++++++++++
> >> >  1 file changed, 21 insertions(+)
> >> >
> >> > diff --git a/drivers/platform/x86/intel-vbtn.c
> >> > b/drivers/platform/x86/intel-vbtn.c index 58c5ff3..64b4b34 100644
> >> > --- a/drivers/platform/x86/intel-vbtn.c
> >> > +++ b/drivers/platform/x86/intel-vbtn.c
> >> > @@ -26,6 +26,9 @@
> >> >  #include <linux/suspend.h>
> >> >  #include <acpi/acpi_bus.h>
> >> >
> >> > +/* When NOT in tablet mode, VBDS has the flag 0x40 */
> >> > +#define TABLET_MODE_FLAG 0x40
> >> > +
> >> >  MODULE_LICENSE("GPL");
> >> >  MODULE_AUTHOR("AceLan Kao");
> >> >
> >> > @@ -42,6 +45,8 @@ static const struct key_entry intel_vbtn_keymap[] = {
> >> >     { KE_IGNORE, 0xC5, { KEY_VOLUMEUP } },          /* volume-up key release */
> >> >     { KE_KEY, 0xC6, { KEY_VOLUMEDOWN } },           /* volume-down key press */
> >> >     { KE_IGNORE, 0xC7, { KEY_VOLUMEDOWN } },        /* volume-down key release */
> >> > +   { KE_SW,  0xCC, { .sw = { SW_TABLET_MODE, 1 } } }, /* Tablet mode in */
> >> > +   { KE_SW,  0xCD, { .sw = { SW_TABLET_MODE, 0 } } }, /* Tablet mode out */
> >> >     { KE_END },
> >> >  };
> >> >
> >> > @@ -88,6 +93,7 @@ static void notify_handler(acpi_handle handle, u32 event,
> >> > void *context)
> >> >
> >> >  static int intel_vbtn_probe(struct platform_device *device)
> >> >  {
> >> > +   struct acpi_buffer vgbs_output = { ACPI_ALLOCATE_BUFFER, NULL };
> >> >     acpi_handle handle = ACPI_HANDLE(&device->dev);
> >> >     struct intel_vbtn_priv *priv;
> >> >     acpi_status status;
> >> > @@ -110,6 +116,21 @@ static int intel_vbtn_probe(struct platform_device
> >> > *device) return err;
> >> >     }
> >> >
> >> > +   status = acpi_evaluate_object(handle, "VGBS", NULL, &vgbs_output);
> >> > +   /* VGBS being present and returning something means
> >> > +    * we have a tablet mode switch
> >> > +    */
> >> > +   if (ACPI_SUCCESS(status)) {
> >> > +           union acpi_object *obj = vgbs_output.pointer;
> >> > +
> >> > +           if (obj && obj->type == ACPI_TYPE_INTEGER) {
> >> > +                   input_set_capability(priv->input_dev, EV_SW, SW_TABLET_MODE);
> >> > +                   input_report_switch(priv->input_dev,
> >> > +                                                           SW_TABLET_MODE,
> >> > +                                                           !(obj->integer.value & TABLET_MODE_FLAG));
> >> > +           }
> >> > +   }
> >> > +
> >> >     status = acpi_install_notify_handler(handle,
> >> >                                          ACPI_DEVICE_NOTIFY,
> >> >                                          notify_handler,
> >>
> >> Is there still something to change in this version of the patch?
> >
> > Yes, I already wrote it in thread for older patch version. Calling
> > input_set_capability() is not needed at all because all capabilities are
> > already set by sparse_keymap_setup() function.
> 
> ah, sorry, i somehow missed the answer.
> Wouldn't this cause a problem tough? it was querying VGBS to add the
> switch capability just conditionally
> on models which actually have it, so now being in sparse_keymap, all
> will have that switch available even if not there.
> Now, if this is fine (after all that switch would never be triggered
> on such hardware) i can go forward removing all of that so the patch
> becomes a neat two-liner.

Looking at other drivers and I see that they send initial status of
SW_TABLET_MODE at probe time. I do not know if this is correct or not.
If yes, then you need to call that input_report_switch() as you have.
If not, then then really just 2 line patch is enough.

But in both cases, call to input_set_capability() is not needed.

-- 
Pali Rohár
pali.rohar@...il.com