From: Peng Hongchi <hongchi.peng@xxxxxxxxxxxx> [ Upstream commit 1134289b6b93d73721340b66c310fd985385e8fa ] When using dma_map_sg() to map the scatterlist with iommu enabled, the entries in the scatterlist can be mergerd into less but longer entries in the function __finalise_sg(). So that the number of valid mapped entries is actually smaller than ureq->num_reqs,and there are still some invalid entries in the scatterlist with dma_addr=0xffffffff and len=0. Writing these invalid sg entries into the dma_desc can cause a data transmission error. The function dma_map_sg() returns the number of valid map entries and the return value is assigned to usb_request::num_mapped_sgs in function usb_gadget_map_request_by_dev(). So that just write valid mapped entries into dma_desc according to the usb_request::num_mapped_sgs, and set the IOC bit if it's the last valid mapped entry. This patch poses no risk to no-iommu situation, cause ureq->num_mapped_sgs equals ureq->num_sgs while using dma_direct_map_sg() to map the scatterlist whith iommu disabled. Signed-off-by: Peng Hongchi <hongchi.peng@xxxxxxxxxxxx> Link: https://lore.kernel.org/r/20240523100315.7226-1-hongchi.peng@xxxxxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- drivers/usb/dwc2/gadget.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/usb/dwc2/gadget.c b/drivers/usb/dwc2/gadget.c index b341bbc9f1dad..abc2271799e0a 100644 --- a/drivers/usb/dwc2/gadget.c +++ b/drivers/usb/dwc2/gadget.c @@ -885,10 +885,10 @@ static void dwc2_gadget_config_nonisoc_xfer_ddma(struct dwc2_hsotg_ep *hs_ep, } /* DMA sg buffer */ - for_each_sg(ureq->sg, sg, ureq->num_sgs, i) { + for_each_sg(ureq->sg, sg, ureq->num_mapped_sgs, i) { dwc2_gadget_fill_nonisoc_xfer_ddma_one(hs_ep, &desc, sg_dma_address(sg) + sg->offset, sg_dma_len(sg), - sg_is_last(sg)); + (i == (ureq->num_mapped_sgs - 1))); desc_count += hs_ep->desc_count; } -- 2.43.0
