Artturi did all the coding and I helped with the testing. I have built a thermostat and weather station on a NTC CHIP device with Linux but I prefer to use openbsd. For my requirements an orange pi one seemed sufficient and so I started working to get openbsd running even though it is not officially supported. My temperature, pressure, humidity sensor, BMW280, is on the i2c bus and so I had to get the sxitwi driver working. Artturi, who ported the sxitwi driver, has been extremely helpful (and patient) in setting up the clock structure and driver and code for the BME280 device. The orange pi one is an Allwinner H3 device and the driver was written for a10 and a20. The specs seemed to indicate that the a20 and h3 were very similar and it was not until the driver did not work that I discovered that there is a one bit difference that created a problem. Artturi has written code to take care of the change. How I go to where I am is too long a story for an email. Suffice it to say that I wrote my first computer program in 1966 (Fortran) and as an engineer have worked on both hardware and software development from microprocessors to large clusters of UNIX servers.
-----Original Message----- From: owner-...@openbsd.org [mailto:owner-...@openbsd.org] On Behalf Of Alfred Morgan Sent: Tuesday, September 26, 2017 1:34 PM To: Stephen Graf <s_g...@telus.net> Cc: arm@openbsd.org Subject: Re: possible bug in sxitwi.c for orange pi one (H3) Hi Stephen, Congratulations on finding that driver bug detail. I would like to know more about how you were able to find such a thing. I am really interested in being able to get to the level to do what you just did. Would you care to share your detailed experience on how you were able to find this? Some questions that I have is how in depth is your knowledge in the hardware, OS, and C language? and how did you get to that knowledge level? I know you said you are "not an accomplished c programmer" but you seem to be getting along really well. > Reading the H3 datasheet would lead me to believe that the switwi > driver should work. How did you come up with the idea to focus on the sxitwi driver? > I modified the dtb and the sxitwi driver to set up H3 compatibility, rebuilt the kernel... How did you know what/how to change in the dtb file? Did you cross-compile and how did you set that up? I imagine the development cycle is really slow having to cross-compile, copy files to an sd card, plug sd card into the pi, boot up, wait, and then... how do you know what is happening? maybe something in the dtb was wrong? how would you know exactly? and if something did go wrong then you would probably spend a massive amount of time hunting down the issue and then not to mention going through the bulky cycle of coding/compiling/copying/booting. How do you manage? > I changed the code to set the bit after a status change and the data started flowing! How did you figure a bit needed to be set after a status change when this fact is buried 445 pages deep in documentation? Thanks, -- -alfred
