On Wed, Oct 07, 2015 at 12:41:21PM +0200, Arnd Bergmann wrote:
The virtgpu driver prints the last_seq variable using the %ld or %lu format string, which does not work correctly on all architectures and causes this compiler warning on ARM:
drivers/gpu/drm/virtio/virtgpu_fence.c: In function 'virtio_timeline_value_str': drivers/gpu/drm/virtio/virtgpu_fence.c:64:22: warning: format '%lu' expects argument of type 'long unsigned int', but argument 4 has type 'long long int' [-Wformat=] snprintf(str, size, "%lu", atomic64_read(&fence->drv->last_seq)); ^ drivers/gpu/drm/virtio/virtgpu_debugfs.c: In function 'virtio_gpu_debugfs_irq_info': drivers/gpu/drm/virtio/virtgpu_debugfs.c:37:16: warning: format '%ld' expects argument of type 'long int', but argument 3 has type 'long long int' [-Wformat=] seq_printf(m, "fence %ld %lld\n", ^
In order to avoid the warnings, this changes the format strings to %llu and adds a cast to u64, which makes it work the same way everywhere.
You have to wonder why atomic64_* functions do not use u64 types. If they're not reliant on manipulating 64-bit quantities, then what's the point of calling them atomic _64_.