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Message-ID: <10421710.CQE85uLOqh@vostro.rjw.lan>
Date: Tue, 26 Mar 2013 14:35:50 +0100
From: "Rafael J. Wysocki" <rjw@...k.pl>
To: Danny Baumann <dannybaumann@....de>
Cc: linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
Zhang Rui <rui.zhang@...el.com>, Len Brown <lenb@...nel.org>
Subject: Re: [PATCH v4 1/3] ACPI video: Fix brightness control initialization for some laptops.
On Tuesday, March 19, 2013 05:22:50 PM Danny Baumann wrote:
> In particular, this fixes brightness control initialization for all
> devices that return index values from _BQC and don't happen to have the
> initial index set by the BIOS in their _BCL table. One example for that
> is the Dell Inspiron 15R SE (model number 7520).
>
> What happened for those devices is that acpi_init_brightness queried the
> initial brightness by calling acpi_video_device_lcd_get_level_current.
> This called _BQC, which returned e.g. 13. As _BQC_use_index isn't
> determined at this point (and thus has its initial value of 0), the
> index isn't converted into the actual level. As '13' isn't present in
> the _BCL list, *level is later overwritten with brightness->curr, which
> was initialized to max_level (100) before. Later in
> acpi_init_brightness, level_old (with the value 100) is used as an index
> into the _BCL table, which causes a value outside of the actual table to
> be used as input into acpi_video_device_lcd_set_level(). Depending on
> the (undefined) value of that location, this call will fail, causing the
> brightness control for the device in question not to be enabled.
>
> Fix that by returning the raw value returned by the _BQC call in the
> initialization case.
>
> Signed-off-by: Danny Baumann <dannybaumann@....de>
All patches in the series applied to linux-pm.git/linux-next.
Thanks,
Rafael
> ---
> drivers/acpi/video.c | 43 ++++++++++++++++++++++++++-----------------
> 1 file changed, 26 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/acpi/video.c b/drivers/acpi/video.c
> index 313f959..09e4722 100644
> --- a/drivers/acpi/video.c
> +++ b/drivers/acpi/video.c
> @@ -222,7 +222,7 @@ static int acpi_video_device_lcd_set_level(struct acpi_video_device *device,
> int level);
> static int acpi_video_device_lcd_get_level_current(
> struct acpi_video_device *device,
> - unsigned long long *level, int init);
> + unsigned long long *level, bool raw);
> static int acpi_video_get_next_level(struct acpi_video_device *device,
> u32 level_current, u32 event);
> static int acpi_video_switch_brightness(struct acpi_video_device *device,
> @@ -236,7 +236,7 @@ static int acpi_video_get_brightness(struct backlight_device *bd)
> struct acpi_video_device *vd =
> (struct acpi_video_device *)bl_get_data(bd);
>
> - if (acpi_video_device_lcd_get_level_current(vd, &cur_level, 0))
> + if (acpi_video_device_lcd_get_level_current(vd, &cur_level, false))
> return -EINVAL;
> for (i = 2; i < vd->brightness->count; i++) {
> if (vd->brightness->levels[i] == cur_level)
> @@ -281,7 +281,7 @@ static int video_get_cur_state(struct thermal_cooling_device *cooling_dev, unsig
> unsigned long long level;
> int offset;
>
> - if (acpi_video_device_lcd_get_level_current(video, &level, 0))
> + if (acpi_video_device_lcd_get_level_current(video, &level, false))
> return -EINVAL;
> for (offset = 2; offset < video->brightness->count; offset++)
> if (level == video->brightness->levels[offset]) {
> @@ -452,7 +452,7 @@ static struct dmi_system_id video_dmi_table[] __initdata = {
>
> static int
> acpi_video_device_lcd_get_level_current(struct acpi_video_device *device,
> - unsigned long long *level, int init)
> + unsigned long long *level, bool raw)
> {
> acpi_status status = AE_OK;
> int i;
> @@ -463,6 +463,15 @@ acpi_video_device_lcd_get_level_current(struct acpi_video_device *device,
> status = acpi_evaluate_integer(device->dev->handle, buf,
> NULL, level);
> if (ACPI_SUCCESS(status)) {
> + if (raw) {
> + /*
> + * Caller has indicated he wants the raw
> + * value returned by _BQC, so don't furtherly
> + * mess with the value.
> + */
> + return 0;
> + }
> +
> if (device->brightness->flags._BQC_use_index) {
> if (device->brightness->flags._BCL_reversed)
> *level = device->brightness->count
> @@ -476,16 +485,14 @@ acpi_video_device_lcd_get_level_current(struct acpi_video_device *device,
> device->brightness->curr = *level;
> return 0;
> }
> - if (!init) {
> - /*
> - * BQC returned an invalid level.
> - * Stop using it.
> - */
> - ACPI_WARNING((AE_INFO,
> - "%s returned an invalid level",
> - buf));
> - device->cap._BQC = device->cap._BCQ = 0;
> - }
> + /*
> + * BQC returned an invalid level.
> + * Stop using it.
> + */
> + ACPI_WARNING((AE_INFO,
> + "%s returned an invalid level",
> + buf));
> + device->cap._BQC = device->cap._BCQ = 0;
> } else {
> /* Fixme:
> * should we return an error or ignore this failure?
> @@ -703,7 +710,8 @@ acpi_video_init_brightness(struct acpi_video_device *device)
> if (!device->cap._BQC)
> goto set_level;
>
> - result = acpi_video_device_lcd_get_level_current(device, &level_old, 1);
> + result = acpi_video_device_lcd_get_level_current(device,
> + &level_old, true);
> if (result)
> goto out_free_levels;
>
> @@ -714,7 +722,7 @@ acpi_video_init_brightness(struct acpi_video_device *device)
> if (result)
> goto out_free_levels;
>
> - result = acpi_video_device_lcd_get_level_current(device, &level, 0);
> + result = acpi_video_device_lcd_get_level_current(device, &level, true);
> if (result)
> goto out_free_levels;
>
> @@ -1268,7 +1276,8 @@ acpi_video_switch_brightness(struct acpi_video_device *device, int event)
> goto out;
>
> result = acpi_video_device_lcd_get_level_current(device,
> - &level_current, 0);
> + &level_current,
> + false);
> if (result)
> goto out;
>
>
--
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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