2020年8月11日(火) 18:24 Krzysztof Kozlowski <krzk@xxxxxxxxxx>: > > On Tue, Aug 11, 2020 at 02:59:07PM +0200, Tomasz Figa wrote: > > Hi Sylwester, > > > > 2020年8月11日(火) 13:25 Sylwester Nawrocki <s.nawrocki@xxxxxxxxxxx>: > > > > > > In the .set_rate callback for some PLLs there is a loop polling state > > > of the PLL lock bit and it may become an endless loop when something > > > goes wrong with the PLL. For some PLLs there is already (a duplicated) > > > code for polling with timeout. This patch replaces that code with > > > the readl_relaxed_poll_timeout_atomic() macro and moves it to a common > > > helper function, which is then used for all the PLLs. The downside > > > of switching to the common macro is that we drop the cpu_relax() call. > > > > Tbh. I'm not sure what effect was exactly expected from cpu_relax() in > > the functions which already had timeout handling. Could someone shed > > some light on this? > > For us, it should not matter much, except: > 1. when on A9 with ARM_ERRATA_754327, but we do not enable it on our > platforms, > 2. it is a generic pattern for busy loops. > > On other architectures it could mean something (e.g. yield to other > hyper-threading CPU). Okay, thanks for confirming that it doesn't matter for us. Now, I wonder if the readx_poll_*() helpers are supposed to take all of those into account or on systems which would benefit from such operations, it would be the caller's responsibility. Best regards, Tomasz
