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Date: Sun, 14 Jul 2013 01:02:06 +0200
From: "Rafael J. Wysocki" <rjw@...k.pl>
To: Frederick van der Wyck <fvanderwyck@...il.com>
Cc: Matthew Garrett <mjg59@...f.ucam.org>,
platform-driver-x86@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-acpi@...r.kernel.org
Subject: Re: [PATCH] platform samsung-q10: use ACPI instead of direct EC calls
On Monday, July 08, 2013 10:34:56 PM Frederick van der Wyck wrote:
> On Mon, Jul 08, 2013 at 11:36:54AM -0400, Matthew Garrett wrote:
>
> > you should be able to just use first_ec directly rather than
> > probing yourself.
>
> Thanks, I've made that change below.
>
> > > + for (i = 0; i < SAMSUNGQ10_BL_MAX_INTENSITY; i++) {
> > > + status = acpi_evaluate_object(ec_handle, "_Q63", NULL, NULL);
> >
> > The potential problem here is that there's no guarantee that these event
> > numbers are stable, and a firmware upgrade could change them. Of course,
> > that's also true of the EC registers, but we haven't had anyone complain
> > about the driver suddenly breaking so I'm not hugely enthusiastic about
> > replacing one fragile but seemingly working method with a fragile but
> > unproven one.
>
> That's true. On the other hand, imitating the action of the brightness keys at
> this higher level seems somewhat cleaner and has the advantage that the
> brightness setting is preserved on reboot (as the smi handler stores it in
> nvram). I did test that 63 and 64 are the appropriate event numbers on each of
> the models in the dmi table (although I only tested one firmware version per
> model).
I think we can make this change and if it breaks things for anyone, we'll
revert it.
Thanks,
Rafael
> Signed-off-by: Frederick van der Wyck <fvanderwyck@...il.com>
> ---
> drivers/platform/x86/Kconfig | 2 +-
> drivers/platform/x86/samsung-q10.c | 65 +++++++++++------------------------
> 2 files changed, 22 insertions(+), 45 deletions(-)
>
> diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
> index 8577261..52aed6d 100644
> --- a/drivers/platform/x86/Kconfig
> +++ b/drivers/platform/x86/Kconfig
> @@ -762,7 +762,7 @@ config INTEL_OAKTRAIL
>
> config SAMSUNG_Q10
> tristate "Samsung Q10 Extras"
> - depends on SERIO_I8042
> + depends on ACPI
> select BACKLIGHT_CLASS_DEVICE
> ---help---
> This driver provides support for backlight control on Samsung Q10
> diff --git a/drivers/platform/x86/samsung-q10.c b/drivers/platform/x86/samsung-q10.c
> index 1a90b62..9d6609d 100644
> --- a/drivers/platform/x86/samsung-q10.c
> +++ b/drivers/platform/x86/samsung-q10.c
> @@ -14,16 +14,12 @@
> #include <linux/init.h>
> #include <linux/platform_device.h>
> #include <linux/backlight.h>
> -#include <linux/i8042.h>
> #include <linux/dmi.h>
> +#include <acpi/acpi_drivers.h>
>
> -#define SAMSUNGQ10_BL_MAX_INTENSITY 255
> -#define SAMSUNGQ10_BL_DEFAULT_INTENSITY 185
> +#define SAMSUNGQ10_BL_MAX_INTENSITY 7
>
> -#define SAMSUNGQ10_BL_8042_CMD 0xbe
> -#define SAMSUNGQ10_BL_8042_DATA { 0x89, 0x91 }
> -
> -static int samsungq10_bl_brightness;
> +static acpi_handle ec_handle;
>
> static bool force;
> module_param(force, bool, 0);
> @@ -33,21 +29,26 @@ MODULE_PARM_DESC(force,
> static int samsungq10_bl_set_intensity(struct backlight_device *bd)
> {
>
> - int brightness = bd->props.brightness;
> - unsigned char c[3] = SAMSUNGQ10_BL_8042_DATA;
> + acpi_status status;
> + int i;
>
> - c[2] = (unsigned char)brightness;
> - i8042_lock_chip();
> - i8042_command(c, (0x30 << 8) | SAMSUNGQ10_BL_8042_CMD);
> - i8042_unlock_chip();
> - samsungq10_bl_brightness = brightness;
> + for (i = 0; i < SAMSUNGQ10_BL_MAX_INTENSITY; i++) {
> + status = acpi_evaluate_object(ec_handle, "_Q63", NULL, NULL);
> + if (ACPI_FAILURE(status))
> + return -EIO;
> + }
> + for (i = 0; i < bd->props.brightness; i++) {
> + status = acpi_evaluate_object(ec_handle, "_Q64", NULL, NULL);
> + if (ACPI_FAILURE(status))
> + return -EIO;
> + }
>
> return 0;
> }
>
> static int samsungq10_bl_get_intensity(struct backlight_device *bd)
> {
> - return samsungq10_bl_brightness;
> + return bd->props.brightness;
> }
>
> static const struct backlight_ops samsungq10_bl_ops = {
> @@ -55,28 +56,6 @@ static const struct backlight_ops samsungq10_bl_ops = {
> .update_status = samsungq10_bl_set_intensity,
> };
>
> -#ifdef CONFIG_PM_SLEEP
> -static int samsungq10_suspend(struct device *dev)
> -{
> - return 0;
> -}
> -
> -static int samsungq10_resume(struct device *dev)
> -{
> -
> - struct backlight_device *bd = dev_get_drvdata(dev);
> -
> - samsungq10_bl_set_intensity(bd);
> - return 0;
> -}
> -#else
> -#define samsungq10_suspend NULL
> -#define samsungq10_resume NULL
> -#endif
> -
> -static SIMPLE_DEV_PM_OPS(samsungq10_pm_ops,
> - samsungq10_suspend, samsungq10_resume);
> -
> static int samsungq10_probe(struct platform_device *pdev)
> {
>
> @@ -93,9 +72,6 @@ static int samsungq10_probe(struct platform_device *pdev)
>
> platform_set_drvdata(pdev, bd);
>
> - bd->props.brightness = SAMSUNGQ10_BL_DEFAULT_INTENSITY;
> - samsungq10_bl_set_intensity(bd);
> -
> return 0;
> }
>
> @@ -104,9 +80,6 @@ static int samsungq10_remove(struct platform_device *pdev)
>
> struct backlight_device *bd = platform_get_drvdata(pdev);
>
> - bd->props.brightness = SAMSUNGQ10_BL_DEFAULT_INTENSITY;
> - samsungq10_bl_set_intensity(bd);
> -
> backlight_device_unregister(bd);
>
> return 0;
> @@ -116,7 +89,6 @@ static struct platform_driver samsungq10_driver = {
> .driver = {
> .name = KBUILD_MODNAME,
> .owner = THIS_MODULE,
> - .pm = &samsungq10_pm_ops,
> },
> .probe = samsungq10_probe,
> .remove = samsungq10_remove,
> @@ -172,6 +144,11 @@ static int __init samsungq10_init(void)
> if (!force && !dmi_check_system(samsungq10_dmi_table))
> return -ENODEV;
>
> + ec_handle = ec_get_handle();
> +
> + if (!ec_handle)
> + return -ENODEV;
> +
> samsungq10_device = platform_create_bundle(&samsungq10_driver,
> samsungq10_probe,
> NULL, 0, NULL, 0);
>
--
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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