By mistake during development it may happen or a rogue application can knowingly play with our hardware (commercial product may be vulnerable). What are your thoughts? -Rishi On Mon, Aug 30, 2021 at 6:39 PM Tobias Junghans <tobias.junghans@xxxxxxxx> wrote: > > Hi Rishi, > > thank you for your questions. I agree with you that one usually would > reprogram the flash when manufacturing commercial products. However there's not > always the need to do so if things can be done in software as well. The code > will do no harm since a GPIO line initially is configured as input > (MCP2221_GP_GPIO_DIR_IN) when being requested. Like with any other GPIO > (driver), it's up to the user to take care of not configuring both ends as > outputs with conflicting pull downs/ups or logic levels. Also the driver's > default behaviour remains unchanged, i.e. it will not change the GP pin config > unless requested explicitly. > > So all the proposed patch does it is to make the GPIO functions work as > expected OOTB when explicitly controlling them with the appropriate tools or > interfaces (libgpiod/sysfs). > > Best regards > > Tobias > > > > Hi Tobias, > > > > To me it sounds like we are discussing about commercial product > > (predefined internal flash fw) v/s prototype (we want to play with > > settings at runtime with ease). > > > > Let us assume a GPx pin is configured as input and pulled up in > > hardware board originally. A microcontroller's GPIO is configured as > > output and connected to this GPx on MCP2221. > > MCP2221 (GPx, input, pulled up) <----------- (output, no pull up/down) > > STM32 Microcontroller > > > > 1. The STM32 Microcontroller drives this pin and set it to logic low > > 2. Driver using this patch configure this GPIO on mcp2221 end as > > output and drives it to logic high > > It is like two devices trying to drive same (physical wire) GPIO pin > > at the same time. How we plan to handle this. > > > > Will the GPx side will fuse or malfunction because of infinite current flow > > ? > > > > Regards, > > Rishi > >
