Hi Uwe, Andy, On 5/5/23 11:21, Uwe Kleine-König wrote: > On Fri, May 05, 2023 at 12:07:02PM +0300, Andy Shevchenko wrote: >> On Thu, May 4, 2023 at 7:53 PM Uwe Kleine-König >> <u.kleine-koenig@xxxxxxxxxxxxxx> wrote: >>> On Sun, Apr 30, 2023 at 06:58:06PM +0200, Hans de Goede wrote: >> >> ... >> >>> I don't know much about x86, but I think the table belongs to where this >>> "80862289:00" device is created. >> >> Just for your information, it's in drivers/acpi/acpi_lpss.c. > > Compared to drivers/platform/x86/lenovo-yogabook-wmi.c this file is > never compiled as a module and so patch #1 would become unnecessary. > > That file also already has a pwm_lookup table. Right, the Cherry Trail SoCs in question have 2 PWM controllers the first controller is pretty much always used to control the brightness of the LCD screen. So we have a fixed pwm_lookup table for it there using the SoC's builtin display controller's device_name() as consumer-device-name. The second PWM controller however is different it is mostly unused I'm aware of 2 cases where it is used and in both cases it is used to control the brightness of a backlight for fixed (etched into the glass) touch controls. The problem is that in these cases there will be 2 totally different consumer devices. Looking at the lookup tabel checks in pwm_get() I see that it is possible to add a lookup which matches only by dev_id. So I could use this here and this would then also be in place for when I get around to writing a driver for the second case (that I'm ware of) which needs access to the second PWM controller. So this then just leaves the question of what to name the con-id, since we won't be specifying a consumer-device-name I think it is best to keep the con_id quite generic, e.g.: "pwm_soc_lpss_2" to match with the existing: "pwm_soc_backlight" for the first PWM controller. Uwe, Andy, is using a pwm_lookup with only a con_id match on "pwm_soc_lpss_2" ok with you ? Regards, Hans
