Hello Vince,

Op 28-11-14 om 12:57 schreef Vince Hsu:
Hi Roy,

On 11/28/2014 07:25 PM, Roy Spliet wrote:
Hello Vince,

One minor question inline.

Op 28-11-14 om 12:13 schreef Vince Hsu:
The voltage value are calculated by the hardware characterized
result.

Signed-off-by: Vince Hsu <[email protected]>
---

Resend this patch with the fuse change and proper patch prefix
per Thierry's request.

  drm/Kbuild                   |   1 +
  drm/core/subdev/volt/gk20a.c |   1 +
  nvkm/engine/device/nve0.c    |   1 +
  nvkm/include/subdev/volt.h   |   1 +
  nvkm/subdev/clock/gk20a.c    |  15 ++++
nvkm/subdev/volt/gk20a.c | 202 +++++++++++++++++++++++++++++++++++++++++++
  6 files changed, 221 insertions(+)
  create mode 120000 drm/core/subdev/volt/gk20a.c
  create mode 100644 nvkm/subdev/volt/gk20a.c

diff --git a/drm/Kbuild b/drm/Kbuild
index 728bc5b66b29..7c49e6655066 100644
--- a/drm/Kbuild
+++ b/drm/Kbuild
@@ -225,6 +225,7 @@ nouveau-y += core/subdev/vm/nvc0.o
  nouveau-y += core/subdev/volt/base.o
  nouveau-y += core/subdev/volt/gpio.o
  nouveau-y += core/subdev/volt/nv40.o
+nouveau-y += core/subdev/volt/gk20a.o
    nouveau-y += core/engine/falcon.o
  nouveau-y += core/engine/xtensa.o
diff --git a/drm/core/subdev/volt/gk20a.c b/drm/core/subdev/volt/gk20a.c
new file mode 120000
index 000000000000..2894eb1ede13
--- /dev/null
+++ b/drm/core/subdev/volt/gk20a.c
@@ -0,0 +1 @@
+../../../../nvkm/subdev/volt/gk20a.c
\ No newline at end of file
diff --git a/nvkm/engine/device/nve0.c b/nvkm/engine/device/nve0.c
index b1b2e484ecfa..674da1f095b2 100644
--- a/nvkm/engine/device/nve0.c
+++ b/nvkm/engine/device/nve0.c
@@ -179,6 +179,7 @@ nve0_identify(struct nouveau_device *device)
          device->oclass[NVDEV_ENGINE_GR     ] = gk20a_graph_oclass;
          device->oclass[NVDEV_ENGINE_COPY2  ] = &nve0_copy2_oclass;
          device->oclass[NVDEV_ENGINE_PERFMON] = &nve0_perfmon_oclass;
+        device->oclass[NVDEV_SUBDEV_VOLT   ] = &gk20a_volt_oclass;
          break;
      case 0xf0:
          device->cname = "GK110";
diff --git a/nvkm/include/subdev/volt.h b/nvkm/include/subdev/volt.h
index 820b62ffd75b..67db5e58880d 100644
--- a/nvkm/include/subdev/volt.h
+++ b/nvkm/include/subdev/volt.h
@@ -52,6 +52,7 @@ int  _nouveau_volt_init(struct nouveau_object *);
  #define _nouveau_volt_fini _nouveau_subdev_fini
    extern struct nouveau_oclass nv40_volt_oclass;
+extern struct nouveau_oclass gk20a_volt_oclass;
    int nouveau_voltgpio_init(struct nouveau_volt *);
  int nouveau_voltgpio_get(struct nouveau_volt *);
diff --git a/nvkm/subdev/clock/gk20a.c b/nvkm/subdev/clock/gk20a.c
index 82abbea2be12..fb4fad374bdd 100644
--- a/nvkm/subdev/clock/gk20a.c
+++ b/nvkm/subdev/clock/gk20a.c
@@ -470,76 +470,91 @@ gk20a_pstates[] = {
      {
          .base = {
              .domain[nv_clk_src_gpc] = 72000,
+            .voltage = 0,
          },
      },
      {
          .base = {
              .domain[nv_clk_src_gpc] = 108000,
+            .voltage = 1,
          },
      },
      {
          .base = {
              .domain[nv_clk_src_gpc] = 180000,
+            .voltage = 2,
          },
      },
      {
          .base = {
              .domain[nv_clk_src_gpc] = 252000,
+            .voltage = 3,
          },
      },
      {
          .base = {
              .domain[nv_clk_src_gpc] = 324000,
+            .voltage = 4,
          },
      },
      {
          .base = {
              .domain[nv_clk_src_gpc] = 396000,
+            .voltage = 5,
          },
      },
      {
          .base = {
              .domain[nv_clk_src_gpc] = 468000,
+            .voltage = 6,
          },
      },
      {
          .base = {
              .domain[nv_clk_src_gpc] = 540000,
+            .voltage = 7,
          },
      },
      {
          .base = {
              .domain[nv_clk_src_gpc] = 612000,
+            .voltage = 8,
          },
      },
      {
          .base = {
              .domain[nv_clk_src_gpc] = 648000,
+            .voltage = 9,
          },
      },
      {
          .base = {
              .domain[nv_clk_src_gpc] = 684000,
+            .voltage = 10,
          },
      },
      {
          .base = {
              .domain[nv_clk_src_gpc] = 708000,
+            .voltage = 11,
          },
      },
      {
          .base = {
              .domain[nv_clk_src_gpc] = 756000,
+            .voltage = 12,
          },
      },
      {
          .base = {
              .domain[nv_clk_src_gpc] = 804000,
+            .voltage = 13,
          },
      },
      {
          .base = {
              .domain[nv_clk_src_gpc] = 852000,
+            .voltage = 14,
          },
      },
  };

Is there a particular reason why this table is hard-coded rather than stored in the device tree? It doesn't seem to differ much between different gk20a's (but this might change with the denver-core version?), but I do anticipate a lot of "code" duplication when post-K1 cores are released and supported.
Hmmm.. That's probably because I just realized we have some other example like the bios subdev is using the device tress stuff. The table is chip specific, not board specific. Should we put it in device tree? And the table should be the same between all the gk20a's although there is no guarantee. If the post-K1 cores also integrate the gk20a, they should use the same driver including this file. If not, I believe we will have some clever way to handle that. That's unlikely to happen though. :)

Thanks,
Vince

I'm not sure if I completely understand your reply, so forgive me if I am stating some obvious things: The reason why I brought this up is because, the way I see it, DTS is the replacement for (V)BIOS on ARM platforms, giving a set of parameters that drivers (nouveau) can use for that particular instance (the Tegra K1 SoC) of some more generic IP (gk20a). All the other devices nouveau supports have a VBIOS to describe this kind of information to us, hence we haven't seen this before. For CPUs there are plenty of examples though of such params defined in DT: in arch/arm/boot/dts/ : imx6qdl.dtsi documents the min and max volt for regulators, while the CPUs have a little freq<->volt mapping in imx6q.dtsi. GPUs are new in a sense that NVIDIA is the first to actively support upstream development (thanks!) Secondly, we should keep in mind that DT is not tied to Linux; I believe Linaro's long term goal is to take the DT from the Linux tree and maintain it as a separate tree, to be used with U-boot, *BSD, maybe even Windows. These kind of parameters are not very platform-dependent and although they seem like a little detail that's easy to reproduce on every platform, looking at the sheer size of the VBIOS data that could mean a *lot* of duplication. I bring this up not because I think I know better, but rather because I believe it's a good discussion to have now that there still is little legacy on ARM SoCs in nouveau. DTS is still a work-in-progress, and at this moment we have the opportunity to consider what needs to be documented in there and what doesn't. I would actually love to hear other, more experienced developers chime in as well (Rob Clark? Ben Skeggs? Linaro folks?) and see how they feel.
Cheers,

Roy
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