From: Anup Patel Subject: Re: [PATCH v2 2/5] async_tx: Handle DMA devices having support for fewer PQ coefficients Date: Thu, 9 Feb 2017 14:59:35 +0530 Message-ID: References: <1486455406-11202-1-git-send-email-anup.patel@broadcom.com> <1486455406-11202-3-git-send-email-anup.patel@broadcom.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Cc: Vinod Koul , Rob Herring , Mark Rutland , Herbert Xu , "David S . Miller" , Jassi Brar , Ray Jui , Scott Branden , Jon Mason , Rob Rice , BCM Kernel Feedback , "dmaengine-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Device Tree , "linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org" , "linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , linux-crypto-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-raid To: Dan Williams Return-path: In-Reply-To: Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-crypto.vger.kernel.org On Wed, Feb 8, 2017 at 9:54 PM, Dan Williams wrote: > On Wed, Feb 8, 2017 at 12:57 AM, Anup Patel wrote: >> On Tue, Feb 7, 2017 at 11:46 PM, Dan Williams wrote: >>> On Tue, Feb 7, 2017 at 1:02 AM, Anup Patel wrote: >>>> On Tue, Feb 7, 2017 at 1:57 PM, Dan Williams wrote: >>>>> On Tue, Feb 7, 2017 at 12:16 AM, Anup Patel 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 >>>>>> Reviewed-by: Scott Branden >>>>> >>>>> 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 -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html