On 6/12/26 12:52 PM, Sam Edwards wrote: > On Fri, Jun 12, 2026 at 10:32 AM David Lechner <[email protected]> wrote: >> >> Add 64-bit Mediatek ARM SoCs to the default y setting of >> LMB_LIMIT_DMA_BELOW_RAM_TOP. These platforms have a 4GiB DMA limit, e.g. >> for the SD/MMC controller. > > Hi David, > > Is the 4GiB DMA limit due to the interconnect itself or are there > merely a few blocks that can't speak 64-bit? If the latter, I think > it'd be clearer to associate the setting with the culprit driver(s) > rather than the whole platform, so that it can be removed if/when > those drivers begin to use bounce buffers. > For MediaTek, I think it is mostly specific IP blocks (e.g. MMC in the mt8xxx targets in and NETSYS in mt79xx targets covered by this series are the ones I am aware of).
Weijie Gao, maybe you have more information about this?
