Messages in this thread | | | From | Sven Van Asbroeck <> | Date | Fri, 29 Jan 2021 16:24:06 -0500 | Subject | Re: [PATCH v5 2/7] pwm: pca9685: Support hardware readout |
| |
Hi Clemens,
On Fri, Jan 29, 2021 at 3:37 PM Clemens Gruber <clemens.gruber@pqgruber.com> wrote: > > Is the driver really responsible for bootloaders that program the chip > with invalid values?
No, but it's responsible for correcting invalid values. Otherwise the driver doesn't work.
> The chip comes out of PoR with sane default values. If the bootloader of > a user messes them up, isn't that a bootloader problem instead of a > Linux kernel driver problem?
Invalid values are only half the problem. The other half is that two valid values might produce the same output, e.g.:
LEN_ON = 409, LED_OFF = 1228 and LED_ON = 419, LED_OFF = 1238 produce the same result. you can't see the difference between the two when scoping the channel. there are probably more ways to do this, some might surprise us. It's a tricky chip.
| |