From: Manivannan Sadhasivam Date: Mon, 17 Jul 2023 06:54:58 +0000 (+0530) Subject: PCI: epf-mhi: Use iATU for small transfers X-Git-Tag: v6.6.7~2039^2~8^2~1 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=127c66c3b95feddda664d1d76cae424a592ceac5;p=platform%2Fkernel%2Flinux-starfive.git PCI: epf-mhi: Use iATU for small transfers For transfers below 4K, let's use iATU since using eDMA for such small transfers is inefficient. This is mainly because setting up an eDMA transfer and waiting for completion adds some latency. This latency is negligible for large transfers but not for the smaller ones. With using iATU, there is an increase in ~50Mbps throughput on both MHI UL (Uplink) and DL (Downlink) channels. [kwilczynski: commit log] Link: https://lore.kernel.org/linux-pci/20230717065459.14138-7-manivannan.sadhasivam@linaro.org Signed-off-by: Manivannan Sadhasivam Signed-off-by: Krzysztof Wilczyński --- diff --git a/drivers/pci/endpoint/functions/pci-epf-mhi.c b/drivers/pci/endpoint/functions/pci-epf-mhi.c index fec9743..b7b9d3e 100644 --- a/drivers/pci/endpoint/functions/pci-epf-mhi.c +++ b/drivers/pci/endpoint/functions/pci-epf-mhi.c @@ -284,6 +284,9 @@ static int pci_epf_mhi_edma_read(struct mhi_ep_cntrl *mhi_cntrl, u64 from, dma_addr_t dst_addr; int ret; + if (size < SZ_4K) + return pci_epf_mhi_iatu_read(mhi_cntrl, from, to, size); + mutex_lock(&epf_mhi->lock); config.direction = DMA_DEV_TO_MEM; @@ -350,6 +353,9 @@ static int pci_epf_mhi_edma_write(struct mhi_ep_cntrl *mhi_cntrl, void *from, dma_addr_t src_addr; int ret; + if (size < SZ_4K) + return pci_epf_mhi_iatu_write(mhi_cntrl, from, to, size); + mutex_lock(&epf_mhi->lock); config.direction = DMA_MEM_TO_DEV;