Hi Jean-Nicolas, thanks for your patch! You will have to resent the patch to the DMAengine list and the maintainer (Vinod). Out of curiosity: what platform are you using this on? On Fri, Mar 1, 2019 at 5:18 PM Jean-Nicolas Graux <jean-nicolas.graux@xxxxxx> wrote: > Current way we find a waiting virtual channel for the next transfer > at the time one physical channel becomes free is not really fair. > > More in details, in case there is more than one channel waiting at a time, > by just going through the arrays of memcpy and slave channels and stopping > as soon as state match waiting state, channels with high indexes can be > penalized. > > Whenever dma engine is substantially overloaded so that we constantly > get several channels waiting, channels with highest indexes might not > be served for a substantial time which in the worse case, might hang > task that wait for dma transfer to complete. > > This patch makes physical channel re-assignment more fair by storing > time in jiffies when a channel is put in waiting state. Whenever a > physical channel has to be re-assigned, this time is used to select > channel that is waiting for the longest time. > > Signed-off-by: Jean-Nicolas Graux <jean-nicolas.graux@xxxxxx> That's a neat trick, look like a good idea. Please add some comment in the code in pl08x_phy_free() so it is clear what is going on for people reading the code, with that: Reviewed-by: Linus Walleij <linus.walleij@xxxxxxxxxx> Yours, Linus Walleij
