Messages in this thread | | | From | Martin Blumenstingl <> | Date | Fri, 23 Nov 2018 20:40:28 +0100 | Subject | Re: [PATCH v2 0/2] clocksource/meson6_timer: implement ARM delay timer |
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On Fri, Nov 23, 2018 at 7:15 AM Daniel Lezcano <daniel.lezcano@linaro.org> wrote: > > On 22/11/2018 23:12, Martin Blumenstingl wrote: > > Hi Daniel, > > > > On Sun, Nov 18, 2018 at 2:27 AM Daniel Lezcano > > <daniel.lezcano@linaro.org> wrote: > >> > >> On 15/11/2018 23:46, Martin Blumenstingl wrote: > >>> While trying to add support for the ARM TWD Timer and the ARM Global > >>> Timer on Meson8, Meson8b and Meson8m2 (ARM Cortex-A5 and Cortex-A9 SoCs) > >>> I did a review of the existing driver. > >>> Unfortunately I found it hard to review because the pre-processor > >>> #defines did not match the names from the public S805 datasheet. Thus > >>> patch #1 adjusts these. No functional changes here, this is just > >>> preparation work for patch #2. > >>> > >>> Using the ARM Global Timer (drivers/clocksource/arm_global_timer.c) > >>> would have given us a timer-based delay implementation (so udelay() and > >>> friends would use the timer instead of using a loop-based delay > >>> implementation). Unfortunately we can't use the ARM Global Timer yet > >>> because it's input clock is derived from the CPU clock (which can change > >>> once we enable CPU frequency scaling on these SoCs, for which I will be > >>> sending patches in the near future). > >>> Amlogic's 3.10 kernel uses Timer E as delay timer which (with the > >>> current configuration) has a resolution of 1us. So patch #2 uses > >>> register_current_timer_delay() to register Timer E as ARM delay timer > >>> (which will be especially useful as we have to use udelay() when > >>> changing the CPU clocks during DVFS). > >>> > >>> > >>> Changes since v1 at [0]: > >>> - convert the enums for the input clock (meson6_timera_input_clock and > >>> meson6_timere_input_clock) to simple #defines as these are register > >>> values and not something driver-internal. All other register values > >>> are #defines so it makes sense that these are #defines as well. > >>> > >>> > >>> [0] https://patchwork.kernel.org/cover/10658591/ > >>> > >>> > >>> Martin Blumenstingl (2): > >>> clocksource: meson6_timer: use register names from the datasheet > >>> clocksource: meson6_timer: implement ARM delay timer > >>> > >>> drivers/clocksource/meson6_timer.c | 128 +++++++++++++++++++---------- > >>> 1 file changed, 85 insertions(+), 43 deletions(-) > >> > >> Both applied, thanks! > > thank you for taking my patches > > > > I have one question more: can you please push these patches to a > > repository/branch which is included in -next? > > I'm asking because I'd like to send patches that enable CPU frequency > > scaling on Meson8, Meson8b and Meson8m2. The code to change the CPU > > clock calls udelay(), which (in this special case) needs a delay timer > > to work properly (we can't use jiffies as we're using udelay() *while* > > changing the CPU clock). > > branch pushed [1], should appear in linux-next very soon. awesome, thank you!
Regards Martin
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