| Message ID | 1236672205.2820.119.camel@rzhang-dt (mailing list archive) |
|---|---|
| State | Superseded, archived |
| Headers | show |
On Tuesday 10 March 2009 09:03:25 Zhang Rui wrote: > Subject: check the return value of acpi_video_device_lcd_get_level_current > From: Zhang Rui <rui.zhang@intel.com> > > check the return value of acpi_video_device_lcd_get_level_current > > Signed-off-by: Zhang Rui <rui.zhang@intel.com> > --- > drivers/acpi/video.c | 69 ++++++++++++++++++++++++++++++++++----------------- > 1 file changed, 47 insertions(+), 22 deletions(-) > > Index: linux-2.6/drivers/acpi/video.c > =================================================================== > --- linux-2.6.orig/drivers/acpi/video.c > +++ linux-2.6/drivers/acpi/video.c > @@ -294,7 +294,7 @@ static int acpi_video_device_lcd_get_lev > unsigned long long *level); > static int acpi_video_get_next_level(struct acpi_video_device *device, > u32 level_current, u32 event); > -static void acpi_video_switch_brightness(struct acpi_video_device *device, > +static int acpi_video_switch_brightness(struct acpi_video_device *device, > int event); > static int acpi_video_device_get_state(struct acpi_video_device *device, > unsigned long long *state); > @@ -308,7 +308,9 @@ static int acpi_video_get_brightness(str > int i; > struct acpi_video_device *vd = > (struct acpi_video_device *)bl_get_data(bd); > - acpi_video_device_lcd_get_level_current(vd, &cur_level); > + > + if (acpi_video_device_lcd_get_level_current(vd, &cur_level)) > + return -EINVAL; > for (i = 2; i < vd->brightness->count; i++) { > if (vd->brightness->levels[i] == cur_level) > /* The first two entries are special - see page 575 > @@ -373,7 +375,8 @@ static int video_get_cur_state(struct th > unsigned long long level; > int state; > > - acpi_video_device_lcd_get_level_current(video, &level); > + if (acpi_video_device_lcd_get_level_current(video, &level)) > + return -EINVAL; > for (state = 2; state < video->brightness->count; state++) > if (level == video->brightness->levels[state]) > return sprintf(buf, "%d\n", > @@ -502,11 +505,29 @@ static int > acpi_video_device_lcd_get_level_current(struct acpi_video_device *device, > unsigned long long *level) > { > - if (device->cap._BQC) > - return acpi_evaluate_integer(device->dev->handle, "_BQC", NULL, > - level); > + acpi_status status = AE_OK; > + > + if (device->cap._BQC) { > + status = acpi_evaluate_integer(device->dev->handle, "_BQC", > + NULL, level); > + if (ACPI_SUCCESS(status)) { > + device->brightness->curr = *level; > + return 0; > + } else { > + /* Fixme: > + * should we return an error or ignore this failure? > + * dev->brightness->curr is a cached value which stores > + * the correct current backlight level in most cases. > + * ACPI video backlight still works w/ buggy _BQC. > + * http://bugzilla.kernel.org/show_bug.cgi?id=12233 > + */ I wonder what should go wrong there at all. We should add a warning (using printk(.. FW_BUG...)) if we do ACPI video brightness switching without _BQC. This should be supported, but is a firmware bug and likely fails. (BTW, I recently saw a BIOS with _BCQ function. They said they are going to fix it, but it may be more widespread, e.g. this also is often the case (missing _BQC) on Samsung). I found it by luck disassembling and recompiling the DSDT, a runtime warning would be nice (if it does not already exist). Anyway, if we have _BQC (cap._BQC), evaluation should not fail? Ok, double checking is always a good idea... > + ACPI_WARNING((AE_INFO, "Evaluating _BQC failed")); > + device->cap._BQC = 0; > + } > + } > + > *level = device->brightness->curr; > - return AE_OK; > + return 0; > } > > static int > @@ -773,18 +794,8 @@ static void acpi_video_device_find_cap(s > device->backlight = backlight_device_register(name, > NULL, device, &acpi_backlight_ops); > device->backlight->props.max_brightness = device->brightness->count-3; > - /* > - * If there exists the _BQC object, the _BQC object will be > - * called to get the current backlight brightness. Otherwise > - * the brightness will be set to the maximum. > - */ > - if (device->cap._BQC) > - device->backlight->props.brightness = > - acpi_video_get_brightness(device->backlight); > - else > - device->backlight->props.brightness = > - device->backlight->props.max_brightness; > - backlight_update_status(device->backlight); > + device->backlight->props.brightness = > + acpi_video_get_brightness(device->backlight); I could imagine this introduces a regression on machines without _BQC. IIRC the value which brightness is currently active must be initialized if there is no _BQC function and that seems to happen here. Thomas -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Wed, Mar 11, 2009 at 01:56:00PM +0100, Thomas Renninger wrote: > (BTW, I recently saw a BIOS with _BCQ function. They said they are going to > fix it, but it may be more widespread, e.g. this also is often the case > (missing _BQC) on Samsung). I found it by luck disassembling and > recompiling the DSDT, a runtime warning would be nice (if it does not > already exist). It's not that uncommon - there's a few machines with _BCQ. I actually thought we handled it already, but it seems not. Just adding a cap._BCQ and using it if there's no _BQC sounds like a safe idea.
On Wednesday 11 March 2009 14:04:32 Matthew Garrett wrote: > On Wed, Mar 11, 2009 at 01:56:00PM +0100, Thomas Renninger wrote: > > > (BTW, I recently saw a BIOS with _BCQ function. They said they are going to > > fix it, but it may be more widespread, e.g. this also is often the case > > (missing _BQC) on Samsung). I found it by luck disassembling and > > recompiling the DSDT, a runtime warning would be nice (if it does not > > already exist). > > It's not that uncommon - there's a few machines with _BCQ. I actually > thought we handled it already, but it seems not. Just adding a cap._BCQ > and using it if there's no _BQC sounds like a safe idea. As said, the current brightness must be initialized if there is no _BQC and Rui seem to have been removed that. Also a: printk (KERN_WARN FW_BUG PREFIX "ACPI brightness control misses _BQC function\n"); should be added. Rui, if you are there already, do you mind to add such test. I found by pure luck that a vendor mixed up _BQC and _BCQ by getting one single warning recompiling the DSDT: "_BCQ not a predefined function" (or similar). They are now adding it, but a warning is appropriate IMO in _BQC missing case. Not adding _BQC and doing brightness switching through ACPI brightness functions is a really bad idea in general. Thomas -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Index: linux-2.6/drivers/acpi/video.c =================================================================== --- linux-2.6.orig/drivers/acpi/video.c +++ linux-2.6/drivers/acpi/video.c @@ -294,7 +294,7 @@ static int acpi_video_device_lcd_get_lev unsigned long long *level); static int acpi_video_get_next_level(struct acpi_video_device *device, u32 level_current, u32 event); -static void acpi_video_switch_brightness(struct acpi_video_device *device, +static int acpi_video_switch_brightness(struct acpi_video_device *device, int event); static int acpi_video_device_get_state(struct acpi_video_device *device, unsigned long long *state); @@ -308,7 +308,9 @@ static int acpi_video_get_brightness(str int i; struct acpi_video_device *vd = (struct acpi_video_device *)bl_get_data(bd); - acpi_video_device_lcd_get_level_current(vd, &cur_level); + + if (acpi_video_device_lcd_get_level_current(vd, &cur_level)) + return -EINVAL; for (i = 2; i < vd->brightness->count; i++) { if (vd->brightness->levels[i] == cur_level) /* The first two entries are special - see page 575 @@ -373,7 +375,8 @@ static int video_get_cur_state(struct th unsigned long long level; int state; - acpi_video_device_lcd_get_level_current(video, &level); + if (acpi_video_device_lcd_get_level_current(video, &level)) + return -EINVAL; for (state = 2; state < video->brightness->count; state++) if (level == video->brightness->levels[state]) return sprintf(buf, "%d\n", @@ -502,11 +505,29 @@ static int acpi_video_device_lcd_get_level_current(struct acpi_video_device *device, unsigned long long *level) { - if (device->cap._BQC) - return acpi_evaluate_integer(device->dev->handle, "_BQC", NULL, - level); + acpi_status status = AE_OK; + + if (device->cap._BQC) { + status = acpi_evaluate_integer(device->dev->handle, "_BQC", + NULL, level); + if (ACPI_SUCCESS(status)) { + device->brightness->curr = *level; + return 0; + } else { + /* Fixme: + * should we return an error or ignore this failure? + * dev->brightness->curr is a cached value which stores + * the correct current backlight level in most cases. + * ACPI video backlight still works w/ buggy _BQC. + * http://bugzilla.kernel.org/show_bug.cgi?id=12233 + */ + ACPI_WARNING((AE_INFO, "Evaluating _BQC failed")); + device->cap._BQC = 0; + } + } + *level = device->brightness->curr; - return AE_OK; + return 0; } static int @@ -773,18 +794,8 @@ static void acpi_video_device_find_cap(s device->backlight = backlight_device_register(name, NULL, device, &acpi_backlight_ops); device->backlight->props.max_brightness = device->brightness->count-3; - /* - * If there exists the _BQC object, the _BQC object will be - * called to get the current backlight brightness. Otherwise - * the brightness will be set to the maximum. - */ - if (device->cap._BQC) - device->backlight->props.brightness = - acpi_video_get_brightness(device->backlight); - else - device->backlight->props.brightness = - device->backlight->props.max_brightness; - backlight_update_status(device->backlight); + device->backlight->props.brightness = + acpi_video_get_brightness(device->backlight); kfree(name); device->cdev = thermal_cooling_device_register("LCD", @@ -1749,15 +1760,29 @@ acpi_video_get_next_level(struct acpi_vi } } -static void +static int acpi_video_switch_brightness(struct acpi_video_device *device, int event) { unsigned long long level_current, level_next; + int result = -EINVAL; + if (!device->brightness) - return; - acpi_video_device_lcd_get_level_current(device, &level_current); + goto out; + + result = acpi_video_device_lcd_get_level_current(device, + &level_current); + if (result) + goto out; + level_next = acpi_video_get_next_level(device, level_current, event); + acpi_video_device_lcd_set_level(device, level_next); + +out: + if (result) + printk(KERN_ERR PREFIX "Failed to switch the brightness\n"); + + return result; } static int