Hi all,

After merging the drm tree, today's linux-next build (powerpc
allyesconfig) failed like this:

drivers/gpu/drm/ttm/ttm_pool.c:73:29: error: variably modified 'global_write_combined' at file scope
   73 | static struct ttm_pool_type global_write_combined[TTM_DIM_ORDER];
      |                             ^~~~~~~~~~~~~~~~~~~~~
drivers/gpu/drm/ttm/ttm_pool.c:74:29: error: variably modified 'global_uncached' at file scope
   74 | static struct ttm_pool_type global_uncached[TTM_DIM_ORDER];
      |                             ^~~~~~~~~~~~~~~
drivers/gpu/drm/ttm/ttm_pool.c:76:29: error: variably modified 'global_dma32_write_combined' at file scope
   76 | static struct ttm_pool_type global_dma32_write_combined[TTM_DIM_ORDER];
      |                             ^~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/gpu/drm/ttm/ttm_pool.c:77:29: error: variably modified 'global_dma32_uncached' at file scope
   77 | static struct ttm_pool_type global_dma32_uncached[TTM_DIM_ORDER];
      |                             ^~~~~~~~~~~~~~~~~~~~~

Caused by commit

  322458c2bb1a ("drm/ttm: Reduce the number of used allocation orders for TTM pages")

PMD_SHIFT is not necessarily a constant on ppc (see
arch/powerpc/include/asm/book3s/64/pgtable.h).

I have reverted that commit for today.

-- 
Cheers,
Stephen Rothwell