On Wed, Feb 8, 2017 at 9:54 PM, Dan Williams <dan.j.williams@xxxxxxxxx> wrote: > On Wed, Feb 8, 2017 at 12:57 AM, Anup Patel <anup.patel@xxxxxxxxxxxx> wrote: >> On Tue, Feb 7, 2017 at 11:46 PM, Dan Williams <dan.j.williams@xxxxxxxxx> wrote: >>> On Tue, Feb 7, 2017 at 1:02 AM, Anup Patel <anup.patel@xxxxxxxxxxxx> wrote: >>>> On Tue, Feb 7, 2017 at 1:57 PM, Dan Williams <dan.j.williams@xxxxxxxxx> wrote: >>>>> On Tue, Feb 7, 2017 at 12:16 AM, Anup Patel <anup.patel@xxxxxxxxxxxx> wrote: >>>>>> The DMAENGINE framework assumes that if PQ offload is supported by a >>>>>> DMA device then all 256 PQ coefficients are supported. This assumption >>>>>> does not hold anymore because we now have BCM-SBA-RAID offload engine >>>>>> which supports PQ offload with limited number of PQ coefficients. >>>>>> >>>>>> This patch extends async_tx APIs to handle DMA devices with support >>>>>> for fewer PQ coefficients. >>>>>> >>>>>> Signed-off-by: Anup Patel <anup.patel@xxxxxxxxxxxx> >>>>>> Reviewed-by: Scott Branden <scott.branden@xxxxxxxxxxxx> >>>>> >>>>> I don't like this approach. Define an interface for md to query the >>>>> offload engine once at the beginning of time. We should not be adding >>>>> any new extensions to async_tx. >>>> >>>> Even if we do capability checks in Linux MD, we still need a way >>>> for DMAENGINE drivers to advertise number of PQ coefficients >>>> handled by the HW. >>>> >>>> I agree capability checks should be done once in Linux MD but I don't >>>> see why this has to be part of BCM-SBA-RAID driver patches. We need >>>> separate patchsets to address limitations of async_tx framework. >>> >>> Right, separate enabling before we pile on new hardware support to a >>> known broken framework. >> >> Linux Async Tx not broken framework. The issue is: >> 1. Its not complete enough >> 2. Its not optimized for very high through-put offload engines > > I'm not understanding your point. I'm nak'ing this change to add yet > more per-transaction capability checking to async_tx. I don't like the > DMA_HAS_FEWER_PQ_COEF flag, especially since it is equal to > DMA_HAS_PQ_CONTINUE. I'm not asking for all of async_tx's problems to > be fixed before this new hardware support, I'm simply saying we should > start the process of moving offload-engine capability checking to the > raid code. The DMA_HAS_FEWER_PQ_COEF is not equal to DMA_HAS_PQ_CONTINUE. I will try to drop this patch and take care of unsupported PQ coefficients in BCM-SBA-RAID driver itself even if this means doing some computations in BCM-SBA-RAID driver itself. Regards, Anup
