[PATCH umr] Avoid opening the DRM file by default

[Alex Deucher]

On Thu, Apr 27, 2017 at 12:41 PM, Tom St Denis <tom.stdenis at amd.com> wrote:
> Opening the DRM file (/dev/dri/card%d) triggers all sorts of KMD
> work to happen which is not useful if the KMD is hung or not working.
>
> Since --top is the only user of the file currently we simply defer
> opening it until --top is invoked.
>
> Signed-off-by: Tom St Denis <tom.stdenis at amd.com>

Reviewed-by: Alex Deucher <alexander.deucher at amd.com>

> ---
>  src/app/top.c      | 7 +++++++
>  src/lib/discover.c | 3 +--
>  2 files changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/src/app/top.c b/src/app/top.c
> index 364180eb70f6..a4d3aa8e699d 100644
> --- a/src/app/top.c
> +++ b/src/app/top.c
> @@ -933,8 +933,15 @@ void umr_top(struct umr_asic *asic)
>         time_t tt;
>         uint64_t ts;
>         char hostname[64] = { 0 };
> +       char fname[64];
>         pthread_t sensor_thread;
>
> +       // open drm file if not already open
> +       if (asic->fd.drm < 0) {
> +               snprintf(fname, sizeof(fname)-1, "/dev/dri/card%d", asic->instance);
> +               asic->fd.drm = open(fname, O_RDWR);
> +       }
> +
>         if (getenv("HOSTNAME")) strcpy(hostname, getenv("HOSTNAME"));
>
>         // init stats
> diff --git a/src/lib/discover.c b/src/lib/discover.c
> index d561efafe4d4..c9c2f74a4818 100644
> --- a/src/lib/discover.c
> +++ b/src/lib/discover.c
> @@ -127,8 +127,7 @@ struct umr_asic *umr_discover_asic(struct umr_options *options)
>                 asic->fd.vram = open(fname, O_RDWR);
>                 snprintf(fname, sizeof(fname)-1, "/sys/kernel/debug/dri/%d/amdgpu_gpr", asic->instance);
>                 asic->fd.gpr = open(fname, O_RDWR);
> -               snprintf(fname, sizeof(fname)-1, "/dev/dri/card%d", asic->instance);
> -               asic->fd.drm = open(fname, O_RDWR);
> +               asic->fd.drm = -1; // default to closed
>                 // if appending to the fd list remember to update close_asic() and discover_by_did()...
>
>                 if (options->use_pci) {
> --
> 2.12.0
>
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