From mboxrd@z Thu Jan 1 00:00:00 1970 From: Geert Uytterhoeven Date: Tue, 08 Dec 2015 16:30:02 +0000 Subject: Re: [PATCH] mtd: sh_flctl: pass FIFO as physical address Message-Id: List-Id: References: <3152458.D3kElfhRW2@wuerfel> In-Reply-To: <3152458.D3kElfhRW2@wuerfel> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-arm-kernel@lists.infradead.org On Tue, Dec 8, 2015 at 4:38 PM, Arnd Bergmann wrote: > 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. Note that since the removal of (ARM) sh7367/sh7377/sh7372 support, this driver is used on SH only. I'll send a patch to update Kconfig. Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds