• Arnd Bergmann's avatar
    mtd: sh_flctl: pass FIFO as physical address · 1873315f
    Arnd Bergmann authored
    By convention, the FIFO address we pass using dmaengine_slave_config
    is a physical address in the form that is understood by the DMA
    engine, as a dma_addr_t, phys_addr_t or resource_size_t.
    
    The sh_flctl driver however passes a virtual __iomem address that
    gets cast to dma_addr_t in the slave driver. This happens to work
    on shmobile because that platform sets up an identity mapping for
    its MMIO regions, but such code is not portable to other platforms,
    and prevents us from ever changing the platform mapping or reusing
    the driver on other architectures like ARM64 that might not have the
    mapping.
    
    We also get a warning about a type mismatch for the case that
    dma_addr_t is wider than a pointer, i.e. when CONFIG_LPAE is set:
    
    drivers/mtd/nand/sh_flctl.c: In function 'flctl_setup_dma':
    drivers/mtd/nand/sh_flctl.c:163:17: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
      cfg.dst_addr = (dma_addr_t)FLDTFIFO(flctl);
    
    This changes the driver to instead pass the physical address of
    the FIFO that is extracted from the MMIO resource, making the
    code more portable and avoiding the warning.
    Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
    Signed-off-by: default avatarBrian Norris <computersforpeace@gmail.com>
    1873315f
sh_flctl.c 28.5 KB