On Thu, Oct 24, 2019 at 02:11:29PM +0100, Mark Brown wrote: > On Thu, Oct 24, 2019 at 02:54:37PM +0200, Alvaro Gamez Machado wrote: > > > I think then the only way this would be feasible is to check if 8 bits is an > > acceptable number for the master and, if it isn't, apply the lowest > > available data width. I believe this cannot break anything, as it leaves 8 > > as the default unless the master can't work with that number, in which case > > it really doesn't matter what client device wants because the hardware can't > > provide it. > > No, that still leaves the slave driver thinking it's sending 8 bits when > really it's sending something else - the default is just 8 bits, if the > controller can't do it then the transfer can't happen and there's an > error. It's not a good idea to carry on if we're likely to introduce > data corruption. Well, yes. But I don't think that's a software issue but a hardware one. If you have a board that has a SPI master that cannot talk to an 8 bits device and you expect to communicate with anything that accepts 8 bits you're not going to be able to. Either the kernel raises an error or it shuts up and tries its best. I understand the first option is better, but I also think that's not a software issue, that hardware simply cannot work as is regardless of what we do in software. The hardware devices simply can't talk to each other. -- Alvaro G. M.
