> -----Original Message----- > From: Serge Semin <Sergey.Semin@xxxxxxxxxxxxxxxxxxxx> > Sent: Wednesday, March 23, 2022 8:48 PM > To: Gustavo Pimentel <gustavo.pimentel@xxxxxxxxxxxx>; Vinod Koul > <vkoul@xxxxxxxxxx>; Jingoo Han <jingoohan1@xxxxxxxxx>; Bjorn Helgaas > <bhelgaas@xxxxxxxxxx>; Frank Li <frank.li@xxxxxxx>; Manivannan Sadhasivam > <manivannan.sadhasivam@xxxxxxxxxx> > Cc: Serge Semin <Sergey.Semin@xxxxxxxxxxxxxxxxxxxx>; Serge Semin > <fancer.lancer@xxxxxxxxx>; Alexey Malahov > <Alexey.Malahov@xxxxxxxxxxxxxxxxxxxx>; Pavel Parkhomenko > <Pavel.Parkhomenko@xxxxxxxxxxxxxxxxxxxx>; Lorenzo Pieralisi > <lorenzo.pieralisi@xxxxxxx>; Rob Herring <robh@xxxxxxxxxx>; Krzysztof > Wilczyński <kw@xxxxxxxxx>; linux-pci@xxxxxxxxxxxxxxx; > dmaengine@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx > Subject: [EXT] [PATCH 01/25] dmaengine: dw-edma: Drop > dma_slave_config.direction field usage > > Caution: EXT Email > > The dma_slave_config.direction field usage in the DW eDMA driver has been > introduced in the commit bd96f1b2f43a ("dmaengine: dw-edma: support local > dma device transfer semantics"). Mainly the change introduced there was > correct (indeed DEV_TO_MEM means using RD-channel and MEM_TO_DEV - > WR-channel for the case of having eDMA accessed locally from > CPU/Application side), but providing an additional > MEM_TO_MEM/DEV_TO_DEV-based semantics was quite redundant if not to say > potentially harmful (when it comes to removing the denoted field). First > of all since the dma_slave_config.direction field has been marked as > obsolete (see [1] and the structure dc [2]) and will be discarded in > future, using it especially in a non-standard way is discouraged. Secondly > in accordance with the commit denoted above the default > dw_edma_device_transfer() semantics has been changed despite what it's > message said. So claiming that the method was left backward compatible was > wrong. > > Anyway let's fix the problems denoted above and simplify the > dw_edma_device_transfer() method by dropping the parsing of the > DMA-channel direction field. Instead of having that implicit > dma_slave_config.direction field semantic we can use the recently added > DW_EDMA_CHIP_LOCAL flag to distinguish between the local and remote DW > eDMA setups thus preserving both cases support. In addition to that an > ASCII-figure has been added to clarify the complication out. > > [1] Documentation/driver-api/dmaengine/provider.rst > [2] include/linux/dmaengine.h: dma_slave_config.direction > > Co-developed-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx> > Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx> > Signed-off-by: Serge Semin <Sergey.Semin@xxxxxxxxxxxxxxxxxxxx> > > --- > > In accordance with agreement with Frank and Manivannan this patch is > supposed to be moved to the series: > Link: > https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore.kern > el.org%2Fdmaengine%2F20220310192457.3090-1- > Frank.Li%40nxp.com%2F&data=04%7C01%7CFrank.Li%40nxp.com%7C4918ae8545e94 > ab137dc08da0d386b3f%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0%7C0%7C6378368332 > 30354384%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTi > I6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=ejkihPy4A5spPj%2BcCgZgheZXdWdnvRQ > 52SOE0wtDqMI%3D&reserved=0 > in place of the patch: > [PATCH v5 6/9] dmaengine: dw-edma: Don't rely on the deprecated "direction" > member > Link: > https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore.kern > el.org%2Fdmaengine%2F20220310192457.3090-7- > Frank.Li%40nxp.com%2F&data=04%7C01%7CFrank.Li%40nxp.com%7C4918ae8545e94 > ab137dc08da0d386b3f%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0%7C0%7C6378368332 > 30354384%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTi > I6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=qedpXrMGAR9frJWydd9Q63hZDHTYf%2BE > ScsHfIx9019M%3D&reserved=0 > --- Did you have extern git, so I can pull patch from it. Our Email server change patch's format, which cause git am failure and https://patchwork.kernel.org/ still have not this patches yet, or send two patches as attachment to me . Best regards Frank Li > drivers/dma/dw-edma/dw-edma-core.c | 49 +++++++++++++++++++++--------- > 1 file changed, 34 insertions(+), 15 deletions(-) > > diff --git a/drivers/dma/dw-edma/dw-edma-core.c b/drivers/dma/dw-edma/dw- > edma-core.c > index 5be8a5944714..e9e32ed74aa9 100644 > --- a/drivers/dma/dw-edma/dw-edma-core.c > +++ b/drivers/dma/dw-edma/dw-edma-core.c > @@ -339,21 +339,40 @@ dw_edma_device_transfer(struct dw_edma_transfer *xfer) > if (!chan->configured) > return NULL; > > - switch (chan->config.direction) { > - case DMA_DEV_TO_MEM: /* local DMA */ > - if (dir == DMA_DEV_TO_MEM && chan->dir == EDMA_DIR_READ) > - break; > - return NULL; > - case DMA_MEM_TO_DEV: /* local DMA */ > - if (dir == DMA_MEM_TO_DEV && chan->dir == EDMA_DIR_WRITE) > - break; > - return NULL; > - default: /* remote DMA */ > - if (dir == DMA_MEM_TO_DEV && chan->dir == EDMA_DIR_READ) > - break; > - if (dir == DMA_DEV_TO_MEM && chan->dir == EDMA_DIR_WRITE) > - break; > - return NULL; > + /* > + * Local Root Port/End-point Remote End-point > + * +-----------------------+ PCIe bus +----------------------+ > + * | | +-+ | | > + * | DEV_TO_MEM Rx Ch <----+ +---+ Tx Ch DEV_TO_MEM | > + * | | | | | | > + * | MEM_TO_DEV Tx Ch +----+ +---> Rx Ch MEM_TO_DEV | > + * | | +-+ | | > + * +-----------------------+ +----------------------+ > + * > + * 1. Normal logic: > + * If eDMA is embedded into the DW PCIe RP/EP and controlled from > the > + * CPU/Application side, the Rx channel (EDMA_DIR_READ) will be > used > + * for the device read operations (DEV_TO_MEM) and the Tx channel > + * (EDMA_DIR_WRITE) - for the write operations (MEM_TO_DEV). > + * > + * 2. Inverted logic: > + * If eDMA is embedded into a Remote PCIe EP and is controlled by > the > + * MWr/MRd TLPs sent from the CPU's PCIe host controller, the Tx > + * channel (EDMA_DIR_WRITE) will be used for the device read > operations > + * (DEV_TO_MEM) and the Rx channel (EDMA_DIR_READ) - for the write > + * operations (MEM_TO_DEV). > + * > + * It is the client driver responsibility to choose a proper > channel > + * for the DMA transfers. > + */ > + if (chan->dw->chip->flags & DW_EDMA_CHIP_LOCAL) { > + if ((chan->dir == EDMA_DIR_READ && dir != DMA_DEV_TO_MEM) > || > + (chan->dir == EDMA_DIR_WRITE && dir != DMA_MEM_TO_DEV)) > + return NULL; > + } else { > + if ((chan->dir == EDMA_DIR_WRITE && dir != DMA_DEV_TO_MEM) > || > + (chan->dir == EDMA_DIR_READ && dir != DMA_MEM_TO_DEV)) > + return NULL; > } > > if (xfer->type == EDMA_XFER_CYCLIC) { > -- > 2.35.1