On Thu, Apr 25, 2024 at 1:32 PM Christian Gmeiner <christian.gmeiner@xxxxxxxxx> wrote: > > Hi Tomeu, > > > > > If we expose a render node for NPUs without rendering capabilities, the > > userspace stack will offer it to compositors and applications for > > rendering, which of course won't work. > > > > Userspace is probably right in not questioning whether a render node > > might not be capable of supporting rendering, so change it in the kernel > > instead by exposing a /dev/accel node. > > > > Before we bring the device up we don't know whether it is capable of > > rendering or not (depends on the features of its blocks), so first try > > to probe a rendering node, and if we find out that there is no rendering > > hardware, abort and retry with an accel node. > > > > I really love this idea of moving away from a render node. What needs to be done > on the userspace side? Doesn't seem that bad, here is a proof of concept: https://gitlab.freedesktop.org/tomeu/mesa/-/tree/teflon-accel Thanks for taking a look. Tomeu > > Signed-off-by: Tomeu Vizoso <tomeu@xxxxxxxxxxxxxxx> > > Cc: Oded Gabbay <ogabbay@xxxxxxxxxx> > > Reviewed-by: Christian Gmeiner <cgmeiner@xxxxxxxxxx> > > > --- > > drivers/gpu/drm/etnaviv/etnaviv_drv.c | 46 ++++++++++++++++++++++----- > > 1 file changed, 38 insertions(+), 8 deletions(-) > > > > diff --git a/drivers/gpu/drm/etnaviv/etnaviv_drv.c b/drivers/gpu/drm/etnaviv/etnaviv_drv.c > > index 6500f3999c5f..8e7dd23115f4 100644 > > --- a/drivers/gpu/drm/etnaviv/etnaviv_drv.c > > +++ b/drivers/gpu/drm/etnaviv/etnaviv_drv.c > > @@ -11,6 +11,7 @@ > > #include <linux/platform_device.h> > > #include <linux/uaccess.h> > > > > +#include <drm/drm_accel.h> > > #include <drm/drm_debugfs.h> > > #include <drm/drm_drv.h> > > #include <drm/drm_file.h> > > @@ -488,10 +489,10 @@ static const struct drm_ioctl_desc etnaviv_ioctls[] = { > > ETNA_IOCTL(PM_QUERY_SIG, pm_query_sig, DRM_RENDER_ALLOW), > > }; > > > > -DEFINE_DRM_GEM_FOPS(fops); > > +DEFINE_DRM_GEM_FOPS(render_fops); > > +DEFINE_DRM_ACCEL_FOPS(accel_fops); > > > > -static const struct drm_driver etnaviv_drm_driver = { > > - .driver_features = DRIVER_GEM | DRIVER_RENDER, > > +static struct drm_driver etnaviv_drm_driver = { > > .open = etnaviv_open, > > .postclose = etnaviv_postclose, > > .gem_prime_import_sg_table = etnaviv_gem_prime_import_sg_table, > > @@ -500,7 +501,6 @@ static const struct drm_driver etnaviv_drm_driver = { > > #endif > > .ioctls = etnaviv_ioctls, > > .num_ioctls = DRM_ETNAVIV_NUM_IOCTLS, > > - .fops = &fops, > > .name = "etnaviv", > > .desc = "etnaviv DRM", > > .date = "20151214", > > @@ -508,15 +508,20 @@ static const struct drm_driver etnaviv_drm_driver = { > > .minor = 4, > > }; > > > > -/* > > - * Platform driver: > > - */ > > -static int etnaviv_bind(struct device *dev) > > +static int etnaviv_bind_with_type(struct device *dev, u32 type) > > { > > struct etnaviv_drm_private *priv; > > struct drm_device *drm; > > + bool is_compute_only = true; > > int ret; > > > > + etnaviv_drm_driver.driver_features = DRIVER_GEM | type; > > + > > + if (type == DRIVER_RENDER) > > + etnaviv_drm_driver.fops = &render_fops; > > + else > > + etnaviv_drm_driver.fops = &accel_fops; > > + > > drm = drm_dev_alloc(&etnaviv_drm_driver, dev); > > if (IS_ERR(drm)) > > return PTR_ERR(drm); > > @@ -553,6 +558,18 @@ static int etnaviv_bind(struct device *dev) > > > > load_gpu(drm); > > > > + for (unsigned int i = 0; i < ETNA_MAX_PIPES; i++) { > > + struct etnaviv_gpu *g = priv->gpu[i]; > > + > > + if (g && (g->identity.minor_features8 & chipMinorFeatures8_COMPUTE_ONLY) == 0) > > + is_compute_only = false; > > + } > > + > > + if (type == DRIVER_RENDER && is_compute_only) { > > + ret = -EINVAL; > > + goto out_unbind; > > + } > > + > > ret = drm_dev_register(drm, 0); > > if (ret) > > goto out_unbind; > > @@ -571,6 +588,19 @@ static int etnaviv_bind(struct device *dev) > > return ret; > > } > > > > +/* > > + * Platform driver: > > + */ > > +static int etnaviv_bind(struct device *dev) > > +{ > > + int ret = etnaviv_bind_with_type(dev, DRIVER_RENDER); > > + > > + if (ret == -EINVAL) > > + return etnaviv_bind_with_type(dev, DRIVER_COMPUTE_ACCEL); > > + > > + return ret; > > +} > > + > > static void etnaviv_unbind(struct device *dev) > > { > > struct drm_device *drm = dev_get_drvdata(dev); > > -- > > 2.44.0 > > > > > -- > greets > -- > Christian Gmeiner, MSc > > https://christian-gmeiner.info/privacypolicy
