[Intel-gfx] [RFC PATCH i-g-t] lib/i915/perf: Fix non-card0 processing

[Lionel Landwerlin]

On 30/04/2021 19:18, Janusz Krzysztofik wrote:
> IGT i915/perf library functions now always operate on sysfs perf
> attributes of card0 device node, no matter which DRM device fd a user
> passes.  The intention was to always switch to primary device node if
> a user passes a render device node fd, but that breaks handling of
> non-card0 devices.
>
> Instead of forcibly using DRM device minor number 0 when opening a
> device sysfs area, convert device minor number of a user passed device
> fd to the minor number of respective primary (cardX) device node.
>
> Signed-off-by: Janusz Krzysztofik <janusz.krzysztofik at linux.intel.com>
> ---
>   lib/i915/perf.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/lib/i915/perf.c b/lib/i915/perf.c
> index 56d5c0b3a..336824df7 100644
> --- a/lib/i915/perf.c
> +++ b/lib/i915/perf.c
> @@ -376,8 +376,8 @@ open_master_sysfs_dir(int drm_fd)
>   	if (fstat(drm_fd, &st) || !S_ISCHR(st.st_mode))
>                   return -1;
>   
> -        snprintf(path, sizeof(path), "/sys/dev/char/%d:0",
> -                 major(st.st_rdev));
> +        snprintf(path, sizeof(path), "/sys/dev/char/%d:%d",
> +                 major(st.st_rdev), minor(st.st_rdev) & ~128);


Isn't it minor(st.st_rdev) & 0xff ? or even 0x3f ?

Looks like /dev/dri/controlD64 can exist too.


-Lionel


>   
>   	return open(path, O_DIRECTORY);
>   }