On Tue, 4 Oct 2022, Lizhi Hou wrote: > > On 10/4/22 09:43, Ilpo Järvinen wrote: > > On Tue, 4 Oct 2022, Lizhi Hou wrote: > > > > > On 10/4/22 01:18, Ilpo Järvinen wrote: > > > > On Wed, 28 Sep 2022, Lizhi Hou wrote: > > > > > > > > > Add driver to enable PCIe board which uses XDMA (the DMA/Bridge > > > > > Subsystem > > > > > for PCI Express). For example, Xilinx Alveo PCIe devices. > > > > > https://www.xilinx.com/products/boards-and-kits/alveo.html > > > > > > > > > > The XDMA engine support up to 4 Host to Card (H2C) and 4 Card to Host > > > > > (C2H) > > > > > channels. Memory transfers are specified on a per-channel basis in > > > > > descriptor linked lists, which the DMA fetches from host memory and > > > > > processes. Events such as descriptor completion and errors are > > > > > signaled > > > > > using interrupts. The hardware detail is provided by > > > > > https://docs.xilinx.com/r/en-US/pg195-pcie-dma/Introduction > > > > > > > > > > This driver implements dmaengine APIs. > > > > > - probe the available DMA channels > > > > > - use dma_slave_map for channel lookup > > > > > - use virtual channel to manage dmaengine tx descriptors > > > > > - implement device_prep_slave_sg callback to handle host scatter > > > > > gather > > > > > list > > > > > - implement device_config to config device address for DMA > > > > > transfer > > > > > > > > > > Signed-off-by: Lizhi Hou <lizhi.hou@xxxxxxx> > > > > > Signed-off-by: Sonal Santan <sonal.santan@xxxxxxx> > > > > > Signed-off-by: Max Zhen <max.zhen@xxxxxxx> > > > > > Signed-off-by: Brian Xu <brian.xu@xxxxxxx> > > > > > --- > > > > > + *chans = devm_kzalloc(&xdev->pdev->dev, sizeof(**chans) * > > > > > (*chan_num), > > > > > + GFP_KERNEL); > > > > > + if (!*chans) > > > > > + return -ENOMEM; > > > > > + > > > > > + for (i = 0, j = 0; i < pdata->max_dma_channels; i++) { > > > > > + ret = xdma_read_reg(xdev, base + i * XDMA_CHAN_STRIDE, > > > > > + XDMA_CHAN_IDENTIFIER, > > > > > &identifier); > > > > > + if (ret) { > > > > > + xdma_err(xdev, "failed to read channel id: > > > > > %d", ret); > > > > > + return ret; > > > > > + } > > > > Is it ok to not rollback the allocation in case of an error occurs? > > > In this loop, the failures are returned by read/write registers. The > > > read/write register failure indicates serious hardware issue and the > > > hardware > > > may not be rollback in this situation. > > What I meant is that you allocated memory above (to *chans, see above). > > Shouldn't that memory be free in case the hw is not working before you > > return the error from this function? > > > > Check also the other returns below for the same problemx. > > The memory does not need to be freed immediately. And it should not be memory > leak because devm_* is used. Ah, sorry. I think I checked exactly that there wasn't m in it but clearly there is now that I recheck. -- i.
