I worked for almost 2 years at a company with my Linux PC, until one day I requested a laptop for travel and they were shocked that I didn't had one, I asked for one with Linux but was told that that's not possible, that they only had windows laptops. I thought, okays this is temporary, as soon as I'm back from traveling I'll return the laptop and things will be back to normal... when I came back and wanted to return the laptop they said that that was my work computer that I should use for everything, I was like, "you do realize our work runs on a Linux server, right?". But nope, I had to use the Windows laptop until I quit a few months later. I knew of at least a couple other devs who were running Linux, but didn't say anything because then they would be forced to switch too, but at my exit interview I remarked that forcing me to use Windows was part of the reason I had left.

I guess my point is maybe don't make a big fuss and don't try to convince HR people about it, they just don't understand.