Hi Mark, On 18 March 2017 at 03:05, Mark Rutland <[email protected]> wrote: > On Tue, Feb 07, 2017 at 02:50:06AM +0800, [email protected] wrote: >> From: Fu Wei <[email protected]> >> >> Currently, arch_timer_rate is used to store the frequency got from per-cpu >> arch-timer or the memory-mapped (MMIO) timers. But those values come from >> different registers which should all be initialized by firmware. >> >> This patch remove arch_timer_rate, and use arch_timer_sysreg_freq and >> arch_timer_mmio_freq instead. >> >> Signed-off-by: Fu Wei <[email protected]> > > Thanks for attacking this. Generally, I do think this is the right thing > to do. > > However... > >> @@ -1070,10 +1077,9 @@ static int __init arch_timer_mem_init(struct >> device_node *np) >> * Try to determine the frequency from the device tree, >> * if fail, get the frequency from the CNTFRQ reg of MMIO timer. >> */ >> - if (!arch_timer_rate && >> - of_property_read_u32(np, "clock-frequency", &arch_timer_rate)) >> - arch_timer_rate = arch_timer_get_mmio_freq(base); >> - if (!arch_timer_rate) { >> + if (of_property_read_u32(np, "clock-frequency", &arch_timer_mmio_freq)) >> + arch_timer_mmio_freq = arch_timer_get_mmio_freq(base); >> + if (!arch_timer_mmio_freq) { >> pr_err(FW_BUG "frequency not available for MMIO timer.\n"); >> ret = -EINVAL; >> goto out; > > ... unfortunately, I believe that this will break some DT platforms that > have been (unintentionally) relying on the way currently allow the > frequency to be probed from either the MMIO timer or the sysreg timer. >
Ah, I 'm really not aware of this. Thanks for pointing it out. > So while the above was my suggestion, it was not my best. > > For the timebeing, let's leave the single arch_timer_rate, but ensure > that it doesn't get in the way fo the ACPI code, by making the ACPI > probe path: > > * Probe the sysreg timers first, using the sysreg cntfrq(). > > * Probe the MMIO timers second, verifying that each MMIO cntfrq matches > the already-probed sysreg cntfrq. > > ... which is what I believe you suggested previously. OK, NP, will do this way. > > Thanks, > Mark. -- Best regards, Fu Wei Software Engineer Red Hat
