On Fri, Nov 10, 2017 at 10:44:30AM -0600, Kim Phillips wrote: > On Fri, 10 Nov 2017 08:02:01 +0000 > Radu Andrei Alexe <radu.alexe@xxxxxxx> wrote: > > > On 11/9/2017 6:34 PM, Kim Phillips wrote: > > > On Thu, 9 Nov 2017 11:54:13 +0000 > > > Radu Andrei Alexe <radu.alexe@xxxxxxx> wrote: > > >> The next patch version will create the platform device dynamically at > > >> run time. > > > > > > Why create a new device when that h/w already has one? > > > > > > Why doesn't the existing crypto driver register dma capabilities with > > > the dma driver subsystem? > > > > > I can think of two reasons: > > > > 1. The code that this driver introduces has nothing to do with crypto > > and everything to do with dma. > > I would think that at least a crypto "null" algorithm implementation > would share code. > > > Placing the code in the same directory as > > the caam subsystem would only create confusion for the reader of an > > already complex driver. > > this different directory argument seems to be identical to your 2 below: > > > 2. I wanted this driver to be tracked by the dma engine team. They have > > the right expertise to provide adequate feedback. If all the code was in > > the crypto directory they wouldn't know about this driver or any > > subsequent changes to it. > > dma subsystem bits could still be put in the dma area if deemed > necessary but I don't think it is: I see > drivers/crypto/ccp/ccp-dmaengine.c calls dma_async_device_register for > example. which is a shame as it was sneaked past the dmaengine community!! This is the *only* example and there and other examples where people use dmaengine: $ grep -rl dmaengine_prep* drivers/crypto/* |uniq drivers/crypto/atmel-aes.c drivers/crypto/atmel-sha.c drivers/crypto/atmel-tdes.c drivers/crypto/img-hash.c drivers/crypto/omap-aes.c drivers/crypto/omap-des.c drivers/crypto/omap-sham.c drivers/crypto/qce/dma.c drivers/crypto/stm32/stm32-hash.c drivers/crypto/ux500/cryp/cryp_core.c drivers/crypto/ux500/hash/hash_core.c > > I also don't see how that complicates things much further. > > What is the rationale for using the crypto h/w as a dma engine anyway? > Are there supporting performance figures? that is a very good question, perf does matter. Given that we have many folks using it, I think it would help, but yes nothing better than numbers speak for themselves. -- ~Vinod
