On Tue, Oct 03, 2023 at 02:15:42PM +0200, Köry Maincent wrote: > From: Kory Maincent <kory.maincent@xxxxxxxxxxx> > > The Linked list element and pointer are not stored in the same memory as > the HDMA controller register. If the doorbell register is toggled before > the full write of the linked list a race condition error can appears. > In remote setup we can only use a readl to the memory to assured the full > write has occurred. > > Fixes: e74c39573d35 ("dmaengine: dw-edma: Add support for native HDMA") > Signed-off-by: Kory Maincent <kory.maincent@xxxxxxxxxxx> > --- > > Changes in v2: > - Move the sync read in a function. > - Add commments Note you need to resubmit the entire series if any of its part has changed. So please add these patches to your patchset (in place of the 4/5 and 5/5 patches I commented) and resend it as v3. -Serge(y) > --- > drivers/dma/dw-edma/dw-hdma-v0-core.c | 17 +++++++++++++++++ > 1 file changed, 17 insertions(+) > > diff --git a/drivers/dma/dw-edma/dw-hdma-v0-core.c b/drivers/dma/dw-edma/dw-hdma-v0-core.c > index 0cce1880cfdc..9109dd6c2e76 100644 > --- a/drivers/dma/dw-edma/dw-hdma-v0-core.c > +++ b/drivers/dma/dw-edma/dw-hdma-v0-core.c > @@ -221,6 +221,20 @@ static void dw_hdma_v0_core_write_chunk(struct dw_edma_chunk *chunk) > dw_hdma_v0_write_ll_link(chunk, i, control, chunk->ll_region.paddr); > } > > +static void dw_hdma_v0_sync_ll_data(struct dw_edma_chunk *chunk) > +{ > + /* > + * In case of remote HDMA engine setup, the DW PCIe RP/EP internals > + * configuration registers and Application memory are normally accessed > + * over different buses. Ensure LL-data reaches the memory before the > + * doorbell register is toggled by issuing the dummy-read from the remote > + * LL memory in a hope that the posted MRd TLP will return only after the > + * last MWr TLP is completed > + */ > + if (!(chunk->chan->dw->chip->flags & DW_EDMA_CHIP_LOCAL)) > + readl(chunk->ll_region.vaddr.io); > +} > + > static void dw_hdma_v0_core_start(struct dw_edma_chunk *chunk, bool first) > { > struct dw_edma_chan *chan = chunk->chan; > @@ -251,6 +265,9 @@ static void dw_hdma_v0_core_start(struct dw_edma_chunk *chunk, bool first) > /* Set consumer cycle */ > SET_CH_32(dw, chan->dir, chan->id, cycle_sync, > HDMA_V0_CONSUMER_CYCLE_STAT | HDMA_V0_CONSUMER_CYCLE_BIT); > + > + dw_hdma_v0_sync_ll_data(chunk); > + > /* Doorbell */ > SET_CH_32(dw, chan->dir, chan->id, doorbell, HDMA_V0_DOORBELL_START); > } > -- > 2.25.1 >