[Intel-gfx] [PATCH 0/3] LPSS PWM support for devices that support it

Kumar, Shobhit shobhit.kumar at linux.intel.com
Tue Jan 12 22:32:16 PST 2016

On 01/13/2016 11:00 AM, C. B. wrote:
> On 12 January 2016 at 08:59, Shobhit Kumar <shobhit.kumar at intel.com> wrote:
>> Not sending yet to pwm mailing list as this is all untested. C.B. please
>> test the patches and see if they work at all for you. For testing Please
>> enable -
> I applied these patches to 4.4-rc8. So far no progress:
> [   14.251512] [drm:pwm_setup_backlight [i915]] *ERROR* Failed to own
> the pwm chip: pm_backlight

Are you sure this is pm_backlight, it should have printed pwm_backlight 
as that is the name for the PMIC bases PWM. I checked the code and I 
have not made a typo there.

> I dug in a little and found that dev_priv->vbt.dsi.config->pwm_blc ==
> 0,  I wonder if some of these Dell Venue's have different hardware?
> This is the model I have:

This means that this device is using PMIC base PWM and not LPSS. I have 
heard from Brain, that my CRC PWM driver is also broken in latest kernel 
which should be probably used in this device. I am looking into that 


> [   16.370481] Hardware name: Dell Inc. Venue 8 Pro 5830/09RP78, BIOS
> A13 11/27/2015
> Let me know what I can provide to help
> CB
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