+ Christoph On Tue, 3 Dec 2019 11:33:15 +0800 Jun Nie wrote: > > > Jisheng Zhang <Jisheng.Zhang@xxxxxxxxxxxxx> 于2019年12月3日周二 上午10:47写道： > > > > On Mon, 2 Dec 2019 22:41:04 +0800 Jun Nie wrote: > > > > > > > > > > > > > DMA memory cannot cross specific boundary for some SDHCI controller, > > > such as DesignWare SDHCI controller. Add DMA memory boundary dt > > > property and workaround the limitation. > > > > IMHO, the workaround could be implemented in each SDHCI host driver. > > > > eg. drivers/mmc/host/sdhci-of-dwcmshc.c > > > Thanks for the suggestion! Christoph's suggestion can prevent the the issue > from the block layer, thus the code can be shared across all To be honest, I did consider similar solution from block layer, I.E set the seg_boundary_mask, when submitting the workaround last year, but per my understanding, SDHCI limitation is the physical DMA addr can't span one specific boundary, so setting seg_boundary_mask w/ blk_queue_segment_boundary can't work. I'm not sure I understand blk_queue_segment_boundary() properly. May Christoph help to clarify? >From another side, drivers/ata/libata-sff.c also workaround the 64K phy DMA boundary limitation itself rather than from block layer. Thanks > controllers. I prefer > his suggestions. > > Jun
