Re: [PATCH v3 3/3] drm/v3d: Make sure the GPU is on when measuring clocks.

Dave Emett
2019-03-08T16:47:24Z

On Wed, 20 Feb 2019 at 23:37, Eric Anholt <eric@anholt.net> wrote:
>
> You'll get garbage measurements if the registers always read back
> 0xdeadbeef
>
> Signed-off-by: Eric Anholt <eric@anholt.net>

Reviewed-by: Dave Emett <david.emett@broadcom.com>

> ---
> drivers/gpu/drm/v3d/v3d_debugfs.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/drivers/gpu/drm/v3d/v3d_debugfs.c b/drivers/gpu/drm/v3d/v3d_debugfs.c
> index eb2b2d2f8553..a24af2d2f574 100644
> --- a/drivers/gpu/drm/v3d/v3d_debugfs.c
> +++ b/drivers/gpu/drm/v3d/v3d_debugfs.c
> @@ -187,6 +187,11 @@ static int v3d_measure_clock(struct seq_file *m, void *unused)
> uint32_t cycles;
> int core = 0;
> int measure_ms = 1000;
> + int ret;
> +
> + ret = pm_runtime_get_sync(v3d->dev);
> + if (ret < 0)
> + return ret;
>
> if (v3d->ver >= 40) {
> V3D_CORE_WRITE(core, V3D_V4_PCTR_0_SRC_0_3,
> @@ -210,6 +215,9 @@ static int v3d_measure_clock(struct seq_file *m, void *unused)
> cycles / (measure_ms * 1000),
> (cycles / (measure_ms * 100)) % 10);
>
> + pm_runtime_mark_last_busy(v3d->dev);
> + pm_runtime_put_autosuspend(v3d->dev);
> +
> return 0;
> }
>
> --
> 2.20.1
>