On 28/10/23 01:55, Andi Shyti wrote: > Hi Krzysztof, > > On Fri, Oct 27, 2023 at 01:37:05PM +0200, Krzysztof Kozlowski wrote: >> On 27/10/2023 13:27, Krzysztof Kozlowski wrote: >>> On 27/10/2023 05:31, Chris Packham wrote: >>>> Some hardware designs have a GPIO used to control the reset of all the >>>> devices on and I2C bus. It's not possible for every child node to >>>> declare a reset-gpios property as only the first device probed would be >>>> able to successfully request it (the others will get -EBUSY). Represent >> Cc: Mark, >> >> Also this part is not true. If the bus is non-discoverable, then it is >> possible to have reset-gpios in each probed device. You can share GPIOs, >> so no problem with -EBUSY at all. >> >> The problem is doing reset: >> 1. in proper moment for all devices >> 2. without affecting other devices when one unbinds/remove() > yes, I thought that we could get to this point, but I did not > object the patch as I didn't see an immediate better solution. I > would still be OK to merge it until we develop something better. > > Let me mull this over and will be back to the topic. If we're happy with plain GPIOs I can move what I've done so far to somewhere in the I2C core. I know we've got other hardware designs with different controllers that also have muxes connected to a common reset GPIO so I would have ended up moving this code to I2C core eventually. If we're talking a proper reset driver implemented using GPIOs then that might be a bit of bigger task. > Thanks, Krzysztof! > Andi > >> The (2) above is not solveable easy in kernel and we already had nice >> talks about it just few days ago: >> 1. Apple case: >> https://scanmail.trustwave.com/?c=20988&d=1LO75R2nre1LP3TyEWMYg1Is4Mz-YROPQ8JxsJqwkg&u=https%3a%2f%2fsocial%2etreehouse%2esystems%2f%40marcan%2f111268780311634160 >> >> 2. my WSA884x: >> https://scanmail.trustwave.com/?c=20988&d=1LO75R2nre1LP3TyEWMYg1Is4Mz-YROPQ8IvtMfhyQ&u=https%3a%2f%2flore%2ekernel%2eorg%2falsa-devel%2f84f9f1c4-0627-4986-8160-b4ab99469b81%40linaro%2eorg%2f >> >> Last, >> I would like to apologize to you Chris. I understand that bringing such >> feedback at v5 is not that good. I had plenty of time to say something >> earlier, so this is not really professional from my side. I am sorry, >> just my brain did not connect all these topics together. >> >> I apologize. >> >> Best regards, >> Krzysztof
