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SubjectRe: [PATCH 0/3] drm/gk20a: support for reclocking
Does GK20A itself have any kind of thermal protection capabilities? 
Upstream SOCTHERM support is not yet available (though I have a driver
in my tree), so we are thinking of disabling CPU DVFS on boards that
don't have always-on active cooling for now. Same might be necessary for
GPU as well.

On 10/07/14 10:34, Alexandre Courbot wrote:
> This series adds support for reclocking on GK20A. The first two patches touch
> the clock subsystem to allow GK20A to operate, by making the presence of the
> thermal and voltage devices optional, and allowing pstates to be provided
> directly instead of being probed using the BIOS (which Tegra does not have).
>
> The last patch adds the GK20A clock device. Arguably the clock can be seen as a
> stripped-down version of what is seen on NVE0, however instead of using NVE0
> support has been written from scratch using the ChromeOS kernel as a basis.
> There are several reasons for this:
>
> - The ChromeOS driver uses a lookup table for the P coefficient which I could
> not find in the NVE0 driver,
> - Some registers that NVE0 expects to find are not present on GK20A (e.g.
> 0x137120 and 0x137140),
> - Calculation of MNP is done differently from what is performed in
> nva3_pll_calc(), and it might be interesting to compare the two methods,
> - All the same, the programming sequence is done differently in the ChromeOS
> driver and NVE0 could possibly benefit from it (?)
>
> It would be interesting to try and merge both, but for now I prefer to have the
> two coexisting to ensure proper operation on GK20A and besure I don't break
> dGPU support. :)
>
> Regarding the first patch, one might argue that I could as well add thermal
> and voltage devices to GK20A. The reason this is not done is because these
> currently depend heavily on the presence of a BIOS, and will require a rework
> similar to that done in patch 2 for clocks. I would like to make sure this
> approach is approved because applying it to other subdevs.
>
> Alexandre Courbot (3):
> drm/nouveau/clk: make therm and volt devices optional
> drm/nouveau/clk: support for non-BIOS pstates
> drm/gk20a: reclocking support
>
> drivers/gpu/drm/nouveau/Makefile | 1 +
> drivers/gpu/drm/nouveau/core/engine/device/nve0.c | 1 +
> .../gpu/drm/nouveau/core/include/subdev/clock.h | 9 +-
> drivers/gpu/drm/nouveau/core/subdev/clock/base.c | 52 +-
> drivers/gpu/drm/nouveau/core/subdev/clock/gk20a.c | 670 +++++++++++++++++++++
> drivers/gpu/drm/nouveau/core/subdev/clock/nv04.c | 4 +-
> drivers/gpu/drm/nouveau/core/subdev/clock/nv40.c | 4 +-
> drivers/gpu/drm/nouveau/core/subdev/clock/nv50.c | 2 +-
> drivers/gpu/drm/nouveau/core/subdev/clock/nva3.c | 4 +-
> drivers/gpu/drm/nouveau/core/subdev/clock/nvaa.c | 4 +-
> drivers/gpu/drm/nouveau/core/subdev/clock/nvc0.c | 4 +-
> drivers/gpu/drm/nouveau/core/subdev/clock/nve0.c | 4 +-
> 12 files changed, 725 insertions(+), 34 deletions(-)
> create mode 100644 drivers/gpu/drm/nouveau/core/subdev/clock/gk20a.c
>


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