From mboxrd@z Thu Jan 1 00:00:00 1970 From: daniel.lezcano@linaro.org (Daniel Lezcano) Date: Fri, 23 Nov 2018 07:15:19 +0100 Subject: [PATCH v2 0/2] clocksource/meson6_timer: implement ARM delay timer In-Reply-To: References: <20181115224657.14736-1-martin.blumenstingl@googlemail.com> <5ff1a888-cce2-8fd8-a98e-14c3d7c33acf@linaro.org> Message-ID: To: linus-amlogic@lists.infradead.org List-Id: linus-amlogic.lists.infradead.org On 22/11/2018 23:12, Martin Blumenstingl wrote: > Hi Daniel, > > On Sun, Nov 18, 2018 at 2:27 AM Daniel Lezcano > 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. -- Daniel [1] https://git.linaro.org/people/daniel.lezcano/linux.git/log/?h=clockevents/next -- Linaro.org ? Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog