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 <manivannan.sadhasivam@linaro.org>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Add support for Qualcomm Snapdragon SM8450 SoC to the EPF driver. SM8450
has the dedicated PID (0x0306) and supports eDMA. Currently, it has no
fixed PCI class, so it is being advertised as "PCI_CLASS_OTHERS".
Link: https://lore.kernel.org/linux-pci/20230717065459.14138-6-manivannan.sadhasivam@linaro.org
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Add support for Embedded DMA (eDMA) available in the DesignWare PCIe IP
to transfer the MHI buffers between the host and the endpoint. The eDMA
use helps achieve greater throughput as the transfers are offloaded from
CPUs.
For differentiating the iATU and eDMA APIs, the pci_epf_mhi_{read/write}
APIs are renamed to pci_epf_mhi_iatu_{read/write} and separate eDMA
specific APIs pci_epf_mhi_edma_{read/write} are introduced.
Platforms that require eDMA support can pass the MHI_EPF_USE_DMA flag
through pci_epf_mhi_ep_info.
[kwilczynski: commit log]
Link: https://lore.kernel.org/linux-pci/20230717065459.14138-5-manivannan.sadhasivam@linaro.org
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Add PCI Endpoint driver for the Qualcomm MHI (Modem Host Interface) bus.
The driver implements the MHI function over PCI in the endpoint device such
as SDX55 modem. The MHI endpoint function driver acts as a controller
driver for the MHI Endpoint stack and carries out all PCI related
functionality.
Link: https://lore.kernel.org/r/20230602114756.36586-9-manivannan.sadhasivam@linaro.org
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Kishon Vijay Abraham I <kishon@kernel.org>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>