Re: [PATCH 09/13] ARM: imx: Remove unused IO_ADDRESS() macros
flat view
From: Linus Walleij <hidden>
Date: 2020-09-29 13:13:08
On Thu, Sep 17, 2020 at 9:16 AM Arnd Bergmann [off-list ref] wrote:
If all of the devices in here are now also mapped using of_iomap() or ioremap(), then the iotables are not strictly needed any more, but most of them are 1MB section sized, which helps slightly reduce TLB usage compared to non-section ioremap() mappings, so we might want to keep them anyway, possibly with the constants moved from the header into the mm-imx??.c files. Adding Linus to Cc for further thoughts, as he was looking at the early io mappings recently.
There is early fixmap which I think should replace the iotables completely if we can, since it is generic kernel code. I was meaning to look into this "at some point". The early fixmap seems to be page (0x1000) based so the iotables might be more efficient if using 1MB sections but I doubt that it is worth it. The fixmaps are converted to proper ioremaps (at the exact same virtual address) later during boot. At least that is how it looks to me :D Yours, Linus Walleij _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel