Thank you very much for your answer.
For Windows I thought AMD's drivers would not support TRIM for my chipset because of what I read on some forums, for example on this forum I found this link
in which a technician writes :
We do support TRIM but only on our newer SB8xx and above chipsets using drivers -
18.104.22.1683 or newer from our website.
Unfortunately my chipset is older than SB8xx.
But the message is quite old now so maybe it has changed. Do you mean that now there are AMD's drivers that support TRIM even for my rather old chipset ?
For Debian I asked on a linux forum and I've been told that the drivers were built into the kernel so I should be okay as long as I use a recent one.