| Message ID | 20170112111425.3228358-1-arnd@arndb.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thu, Jan 12, 2017 at 12:13:51PM +0100, Arnd Bergmann wrote: > The tegra DRM driver is almost ok without an MMU, but there > is one small warning that I get: > > drivers/gpu/drm/tegra/gem.c: In function 'tegra_drm_mmap': > drivers/gpu/drm/tegra/gem.c:508:12: unused variable 'prot' > > This marks the variable as __maybe_unused instead. > > Signed-off-by: Arnd Bergmann <arnd@arndb.de> > --- > drivers/gpu/drm/tegra/gem.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/tegra/gem.c b/drivers/gpu/drm/tegra/gem.c > index 7d853e6b5ff0..63f14b7a59a0 100644 > --- a/drivers/gpu/drm/tegra/gem.c > +++ b/drivers/gpu/drm/tegra/gem.c > @@ -505,7 +505,7 @@ int tegra_drm_mmap(struct file *file, struct vm_area_struct *vma) > > vma->vm_pgoff = vm_pgoff; > } else { > - pgprot_t prot = vm_get_page_prot(vma->vm_flags); > + pgprot_t prot __maybe_unused = vm_get_page_prot(vma->vm_flags); This seems to me like a suboptimal solution. The reason why this fails is because pgprot_writecombine(prot) for NOMMU translates to __pgprot(0) via a macro. This also means that we need to potentially add a __maybe_unused annotation to every local variable that stores a value that gets passed to pgprot_writecombine(). There fortunately aren't very many of those cases, but I still think that a better solution would be to turn pgprot_writecombine() into a static inline function, so that the parameter would get silently ignored. Or perhaps if it must remain a macro, then doing the following should still avoid the need to modify every call site: #define pgprot_writecombine(prot) ({ (void)prot; __pgprot(0); }) Thierry
diff --git a/drivers/gpu/drm/tegra/gem.c b/drivers/gpu/drm/tegra/gem.c index 7d853e6b5ff0..63f14b7a59a0 100644 --- a/drivers/gpu/drm/tegra/gem.c +++ b/drivers/gpu/drm/tegra/gem.c @@ -505,7 +505,7 @@ int tegra_drm_mmap(struct file *file, struct vm_area_struct *vma) vma->vm_pgoff = vm_pgoff; } else { - pgprot_t prot = vm_get_page_prot(vma->vm_flags); + pgprot_t prot __maybe_unused = vm_get_page_prot(vma->vm_flags); vma->vm_flags |= VM_MIXEDMAP; vma->vm_flags &= ~VM_PFNMAP;
The tegra DRM driver is almost ok without an MMU, but there is one small warning that I get: drivers/gpu/drm/tegra/gem.c: In function 'tegra_drm_mmap': drivers/gpu/drm/tegra/gem.c:508:12: unused variable 'prot' This marks the variable as __maybe_unused instead. Signed-off-by: Arnd Bergmann <arnd@arndb.de> --- drivers/gpu/drm/tegra/gem.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)