[Intel-gfx] [PATCH igt v4] lib: Attempt to load the module for a missing device

[Chris Wilson]

Quoting Petri Latvala (2017-11-15 11:06:02)
> On Tue, Nov 14, 2017 at 09:33:51PM +0000, Chris Wilson wrote:
> > If we asked to open a particular chipset and we find no matching device,
> > try again after attempting to load its module. Previously we only did
> > this for vgem, which is not automatically probed during boot, but if we
> > want to leave the module unloaded we have to try harder when we need the
> > device.
> > 
> > v2: DRIVER_* are already masks (and not shifts). Use a common
> > driver_open for both /dev/dri/cardX and /dev/dri/renderDX.
> > v3: Beware making local variables accidentally static scoped.
> > v4: Beware multiple threads trying and failing to open a device
> > 
> > Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> > ---
> >  lib/drmtest.c | 97 +++++++++++++++++++++++++++++++++++------------------------
> >  1 file changed, 57 insertions(+), 40 deletions(-)
> > 
> > diff --git a/lib/drmtest.c b/lib/drmtest.c
> > index e6bdbc35..37cabd58 100644
> > --- a/lib/drmtest.c
> > +++ b/lib/drmtest.c
> > @@ -44,6 +44,7 @@
> >  #include <sys/syscall.h>
> >  #include <sys/utsname.h>
> >  #include <termios.h>
> > +#include <pthread.h>
> >  
> >  #include "drmtest.h"
> >  #include "i915_drm.h"
> > @@ -235,25 +236,19 @@ static int modprobe(const char *driver)
> >       return igt_kmod_load(driver, "");
> >  }
> >  
> > -/**
> > - * __drm_open_driver:
> > - * @chipset: OR'd flags for each chipset to search, eg. #DRIVER_INTEL
> > - *
> > - * Open the first DRM device we can find, searching up to 16 device nodes
> > - *
> > - * Returns:
> > - * An open DRM fd or -1 on error
> > - */
> > -int __drm_open_driver(int chipset)
> > +static void modprobe_i915(const char *name)
> >  {
> > -     if (chipset & DRIVER_VGEM)
> > -             modprobe("vgem");
> > +     /* When loading i915, we also want to load snd-hda et al */
> > +     igt_i915_driver_load(NULL);
> > +}
> >  
> > +static int __open_device(const char *base, int offset, unsigned int chipset)
> > +{
> >       for (int i = 0; i < 16; i++) {
> >               char name[80];
> >               int fd;
> >  
> > -             sprintf(name, "/dev/dri/card%u", i);
> > +             sprintf(name, "%s%u", base, i + offset);
> >               fd = open(name, O_RDWR);
> >               if (fd == -1)
> >                       continue;
> > @@ -262,16 +257,13 @@ int __drm_open_driver(int chipset)
> >                   has_known_intel_chipset(fd))
> >                       return fd;
> >  
> > -             if (chipset & DRIVER_VC4 &&
> > -                 is_vc4_device(fd))
> > +             if (chipset & DRIVER_VC4 && is_vc4_device(fd))
> >                       return fd;
> >  
> > -             if (chipset & DRIVER_VGEM &&
> > -                 is_vgem_device(fd))
> > +             if (chipset & DRIVER_VGEM && is_vgem_device(fd))
> >                       return fd;
> >  
> > -             if (chipset & DRIVER_VIRTIO &&
> > -                 is_virtio_device(fd))
> > +             if (chipset & DRIVER_VIRTIO && is_virtio_device(fd))
> >                       return fd;
> >  
> >               if (chipset & DRIVER_AMDGPU && is_amd_device(fd))
> > @@ -287,33 +279,58 @@ int __drm_open_driver(int chipset)
> >       return -1;
> >  }
> >  
> > -static int __drm_open_driver_render(int chipset)
> > +static int __open_driver(const char *base, int offset, unsigned int chipset)
> >  {
> > -     char *name;
> > -     int i, fd;
> > -
> > -     for (i = 128; i < (128 + 16); i++) {
> > -             int ret;
> > -
> > -             ret = asprintf(&name, "/dev/dri/renderD%u", i);
> > -             igt_assert(ret != -1);
> > -
> > -             fd = open(name, O_RDWR);
> > -             free(name);
> > +     static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
> > +     static const struct module {
> > +             unsigned int bit;
> > +             const char *module;
> > +             void (*modprobe)(const char *name);
> > +     } modules[] = {
> > +             { DRIVER_AMDGPU, "amdgpu" },
> > +             { DRIVER_INTEL, "i915", modprobe_i915 },
> > +             { DRIVER_VC4, "vc4" },
> > +             { DRIVER_VGEM, "vgem" },
> > +             { DRIVER_VIRTIO, "virtio-gpu" },
> > +             {}
> > +     };
> > +     int fd;
> >  
> > -             if (fd == -1)
> > -                     continue;
> > +     fd = __open_device(base, offset, chipset);
> > +     if (fd != -1)
> > +             return fd;
> >  
> > -             if (!is_i915_device(fd) || !has_known_intel_chipset(fd)) {
> > -                     close(fd);
> > -                     fd = -1;
> > -                     continue;
> > +     pthread_mutex_lock(&mutex);
> > +     for (const struct module *m = modules; m->module; m++) {
> > +             if (chipset & m->bit) {
> > +                     if (m->modprobe)
> > +                             m->modprobe(m->module);
> > +                     else
> > +                             modprobe(m->module);
> >               }
> > -
> > -             return fd;
> >       }
> > +     pthread_mutex_unlock(&mutex);
> >  
> > -     return fd;
> > +     return __open_device(base, offset, chipset);
> > +}
> > +
> > +/**
> > + * __drm_open_driver:
> > + * @chipset: OR'd flags for each chipset to search, eg. #DRIVER_INTEL
> > + *
> > + * Open the first DRM device we can find, searching up to 16 device nodes
> > + *
> > + * Returns:
> > + * An open DRM fd or -1 on error
> > + */
> > +int __drm_open_driver(int chipset)
> > +{
> > +     return __open_driver("/dev/dri/card", 0, chipset);
> > +}
> > +
> > +static int __drm_open_driver_render(int chipset)
> > +{
> > +     return __open_driver("/dev/dri/renerD", 128, chipset);
> 
> s/rener/render/

Hmm, I would have expected to have seen a SKIP. Ah, it fallsback to
/dev/dri/cardN on failure. Thanks,
-Chris