| Message ID | 20240929181936.644910-1-paulk@sys-base.io (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | ARM: topology: Allow missing CPU clock-frequency device-tree property | expand |
Hi! Le Sun 29 Sep 24, 20:19, Paul Kocialkowski a écrit : > Allow the fallback mechanism to continue by assuming the same nominal > frequency for all CPU cores, while still benefiting from the static > coefficient provided by the compatible-driven table entries. > This is similar to what is done in the common arch topology code when > it fails to find a clock to get the frequency from. Any thoughts about this patch? Thanks! Paul > The ranging mechanism (using the middle capacity) is unaffected by > the use of a unit frequency and still returns values in the requested > range. > > Also add a comment to clarify what is going on. > > Signed-off-by: Paul Kocialkowski <contact@paulk.fr> > --- > arch/arm/kernel/topology.c | 22 ++++++++++++++++------ > 1 file changed, 16 insertions(+), 6 deletions(-) > > diff --git a/arch/arm/kernel/topology.c b/arch/arm/kernel/topology.c > index 2336ee2aa44a..0eb743c65166 100644 > --- a/arch/arm/kernel/topology.c > +++ b/arch/arm/kernel/topology.c > @@ -119,13 +119,23 @@ static void __init parse_dt_topology(void) > if (cpu_eff->compatible == NULL) > continue; > > + /* > + * Use the legacy clock-frequency property (representing the > + * maximum achievable clock frequency) as an efficiency > + * coefficient (divided by 2^20, roughly 1 MHz) to the table > + * value. If no such property is available, use the table value > + * directly and assume all CPUs are running at the same > + * nominal frequency. > + * > + * It is assumed that clock-frequency is either provided for all > + * CPUs or for none of them. > + */ > rate = of_get_property(cn, "clock-frequency", &len); > - if (!rate || len != 4) { > - pr_err("%pOF missing clock-frequency property\n", cn); > - continue; > - } > - > - capacity = ((be32_to_cpup(rate)) >> 20) * cpu_eff->efficiency; > + if (rate && len == 4) > + capacity = ((be32_to_cpup(rate)) >> 20) * > + cpu_eff->efficiency; > + else > + capacity = cpu_eff->efficiency; > > /* Save min capacity of the system */ > if (capacity < min_capacity) > -- > 2.46.2 > >
diff --git a/arch/arm/kernel/topology.c b/arch/arm/kernel/topology.c index 2336ee2aa44a..0eb743c65166 100644 --- a/arch/arm/kernel/topology.c +++ b/arch/arm/kernel/topology.c @@ -119,13 +119,23 @@ static void __init parse_dt_topology(void) if (cpu_eff->compatible == NULL) continue; + /* + * Use the legacy clock-frequency property (representing the + * maximum achievable clock frequency) as an efficiency + * coefficient (divided by 2^20, roughly 1 MHz) to the table + * value. If no such property is available, use the table value + * directly and assume all CPUs are running at the same + * nominal frequency. + * + * It is assumed that clock-frequency is either provided for all + * CPUs or for none of them. + */ rate = of_get_property(cn, "clock-frequency", &len); - if (!rate || len != 4) { - pr_err("%pOF missing clock-frequency property\n", cn); - continue; - } - - capacity = ((be32_to_cpup(rate)) >> 20) * cpu_eff->efficiency; + if (rate && len == 4) + capacity = ((be32_to_cpup(rate)) >> 20) * + cpu_eff->efficiency; + else + capacity = cpu_eff->efficiency; /* Save min capacity of the system */ if (capacity < min_capacity)