On 12/21/23 11:09, Andrew Halaney wrote:
Currently a wmb() is used to ensure that writes to the
UTP_TASK_REQ_LIST_BASE* regs are completed prior to following writes to
the run/stop registers.
wmb() ensure that the write completes, but completion doesn't mean that
it isn't stored in a buffer somewhere. The recommendation for
ensuring the bits have taken effect on the device is to perform a read
back to force it to make it all the way to the device. This is
documented in device-io.rst and a talk by Will Deacon on this can
be seen over here:
https://youtu.be/i6DayghhA8Q?si=MiyxB5cKJXSaoc01&t=1678
Let's do that to ensure the bits hit the device. Because the wmb()'s
purpose wasn't to add extra ordering (on top of the ordering guaranteed
by writel()/readl()), it can safely be removed.
Reviewed-by: Bart Van Assche <bvanassche@xxxxxxx>
