Thanks for submitting this patch Tobias, I ran into the same issue using the GPIO pins on the MCP2221. I don't have prior experience with Linux driver dev, but I'm going to add some thoughts anyway. The approach of configuring the pins for GPIO operation on request/free makes sense to me as opposed to assuming they were already configured somehow beforehand. Aside from being inconvenient, assuming correct configuration seems like a recipe for accidentally shorting the pin, which Rishi is concerned about. With regards to your patch, I find it odd that the handler for the MCP2221_SRAM_SETTINGS_GET event sets gp_default_settings. Instead, I suggest it set gp_runtime_settings then memcpys from gp_runtime_settings to gp_default_settings at the bottom of probe. And rename mcp_get_gp_default_settings to mcp_get_gp_settings. I ran into another bug in this driver which I think makes sense to fix in this patch set: direction and value are flipped in the mcp_get_gpio struct. According to the data sheet, value comes before direction for each pin. With this patch and that last bug fixed, I have tested the driver and GPIO operations are now working for me.
