On Thu, Feb 9, 2017 at 1:29 AM, Anup Patel <anup.patel@xxxxxxxxxxxx> wrote: > 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. #define DMA_HAS_PQ_CONTINUE (1 << 15 #define DMA_HAS_FEWER_PQ_COEF (1 << 15) > 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. That should be nak'd as well, please do capability detection in a routine that is common to all raid engines. -- To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
